added mpv configs
This commit is contained in:
parent
e2bfb0798c
commit
e5fe648676
155
mpv/.config/mpv/encoding.rst
Normal file
155
mpv/.config/mpv/encoding.rst
Normal file
@ -0,0 +1,155 @@
|
||||
General usage
|
||||
=============
|
||||
|
||||
::
|
||||
|
||||
mpv infile --o=outfile [--of=outfileformat] [--ofopts=formatoptions] [--orawts] \
|
||||
[(any other mpv options)] \
|
||||
--ovc=outvideocodec [--ovcopts=outvideocodecoptions] \
|
||||
--oac=outaudiocodec [--oacopts=outaudiocodecoptions]
|
||||
|
||||
Help for these options is provided if giving help as parameter, as in::
|
||||
|
||||
mpv --ovc=help
|
||||
|
||||
The suboptions of these generally are identical to ffmpeg's (as option parsing
|
||||
is simply delegated to ffmpeg). The option --ocopyts enables copying timestamps
|
||||
from the source as-is, instead of fixing them to match audio playback time
|
||||
(note: this doesn't work with all output container formats); --orawts even turns
|
||||
off discontinuity fixing.
|
||||
|
||||
Note that if neither --ofps nor --oautofps is specified, VFR encoding is assumed
|
||||
and the time base is 24000fps. --oautofps sets --ofps to a guessed fps number
|
||||
from the input video. Note that not all codecs and not all formats support VFR
|
||||
encoding, and some which do have bugs when a target bitrate is specified - use
|
||||
--ofps or --oautofps to force CFR encoding in these cases.
|
||||
|
||||
Of course, the options can be stored in a profile, like this .config/mpv/mpv.conf
|
||||
section::
|
||||
|
||||
[myencprofile]
|
||||
vf-add = scale=480:-2
|
||||
ovc = libx264
|
||||
ovcopts-add = preset=medium
|
||||
ovcopts-add = tune=fastdecode
|
||||
ovcopts-add = crf=23
|
||||
ovcopts-add = maxrate=1500k
|
||||
ovcopts-add = bufsize=1000k
|
||||
ovcopts-add = rc_init_occupancy=900k
|
||||
ovcopts-add = refs=2
|
||||
ovcopts-add = profile=baseline
|
||||
oac = aac
|
||||
oacopts-add = b=96k
|
||||
|
||||
It's also possible to define default encoding options by putting them into
|
||||
the section named ``[encoding]``. (This behavior changed after mpv 0.3.x. In
|
||||
mpv 0.3.x, config options in the default section / no section were applied
|
||||
to encoding. This is not the case anymore.)
|
||||
|
||||
One can then encode using this profile using the command::
|
||||
|
||||
mpv infile --o=outfile.mp4 --profile=myencprofile
|
||||
|
||||
Some example profiles are provided in a file
|
||||
etc/encoding-profiles.conf; as for this, see below.
|
||||
|
||||
|
||||
Encoding examples
|
||||
=================
|
||||
|
||||
These are some examples of encoding targets this code has been used and tested
|
||||
for.
|
||||
|
||||
Typical MPEG-4 Part 2 ("ASP", "DivX") encoding, AVI container::
|
||||
|
||||
mpv infile --o=outfile.avi \
|
||||
--vf=fps=25 \
|
||||
--ovc=mpeg4 --ovcopts=qscale=4 \
|
||||
--oac=libmp3lame --oacopts=b=128k
|
||||
|
||||
Note: AVI does not support variable frame rate, so the fps filter must be used.
|
||||
The frame rate should ideally match the input (25 for PAL, 24000/1001 or
|
||||
30000/1001 for NTSC)
|
||||
|
||||
Typical MPEG-4 Part 10 ("AVC", "H.264") encoding, Matroska (MKV) container::
|
||||
|
||||
mpv infile --o=outfile.mkv \
|
||||
--ovc=libx264 --ovcopts=preset=medium,crf=23,profile=baseline \
|
||||
--oac=libopus --oacopts=qscale=3
|
||||
|
||||
Typical MPEG-4 Part 10 ("AVC", "H.264") encoding, MPEG-4 (MP4) container::
|
||||
|
||||
mpv infile --o=outfile.mp4 \
|
||||
--ovc=libx264 --ovcopts=preset=medium,crf=23,profile=baseline \
|
||||
--oac=aac --oacopts=b=128k
|
||||
|
||||
Typical VP8 encoding, WebM (restricted Matroska) container::
|
||||
|
||||
mpv infile -o outfile.mkv \
|
||||
--of=webm \
|
||||
--ovc=libvpx --ovcopts=qmin=6,b=1000000k \
|
||||
--oac=libopus --oacopts=qscale=3
|
||||
|
||||
|
||||
Device targets
|
||||
==============
|
||||
|
||||
As the options for various devices can get complex, profiles can be used.
|
||||
|
||||
An example profile file for encoding is provided in
|
||||
etc/encoding-profiles.conf in the source tree. This file is installed and loaded
|
||||
by default. If you want to modify it, you can replace and it with your own copy
|
||||
by doing::
|
||||
|
||||
mkdir -p ~/.mpv
|
||||
cp /etc/mpv/encoding-profiles.conf ~/.mpv/encoding-profiles.conf
|
||||
|
||||
Keep in mind that the default profile is the playback one. If you want to add
|
||||
options that apply only in encoding mode, put them into a ``[encoding]``
|
||||
section.
|
||||
|
||||
Refer to the top of that file for more comments - in a nutshell, the following
|
||||
options are added by it::
|
||||
|
||||
--profile=enc-to-dvdpal # DVD-Video PAL, use dvdauthor -v pal+4:3 -a ac3+en
|
||||
--profile=enc-to-dvdntsc # DVD-Video NTSC, use dvdauthor -v ntsc+4:3 -a ac3+en
|
||||
--profile=enc-to-bb-9000 # MP4 for Blackberry Bold 9000
|
||||
--profile=enc-to-nok-6300 # 3GP for Nokia 6300
|
||||
--profile=enc-to-psp # MP4 for PlayStation Portable
|
||||
--profile=enc-to-iphone # MP4 for iPhone
|
||||
--profile=enc-to-iphone-4 # MP4 for iPhone 4 (double res)
|
||||
--profile=enc-to-iphone-5 # MP4 for iPhone 5 (even larger res)
|
||||
|
||||
You can encode using these with a command line like::
|
||||
|
||||
mpv infile --o=outfile.mp4 --profile=enc-to-bb-9000
|
||||
|
||||
Of course, you are free to override options set by these profiles by specifying
|
||||
them after the -profile option.
|
||||
|
||||
|
||||
What works
|
||||
==========
|
||||
|
||||
* Encoding at variable frame rate (default)
|
||||
* Encoding at constant frame rate using --vf=fps=RATE
|
||||
* 2-pass encoding (specify flags=+pass1 in the first pass's --ovcopts, specify
|
||||
flags=+pass2 in the second pass)
|
||||
* Hardcoding subtitles using vobsub, ass or srt subtitle rendering (just
|
||||
configure mpv for the subtitles as usual)
|
||||
* Hardcoding any other mpv OSD (e.g. time codes, using --osdlevel=3 and
|
||||
--vf=expand=::::1)
|
||||
* Encoding directly from a DVD, network stream, webcam, or any other source
|
||||
mpv supports
|
||||
* Using x264 presets/tunings/profiles (by using profile=, tune=, preset= in the
|
||||
--ovcopts)
|
||||
* Deinterlacing/Inverse Telecine with any of mpv's filters for that
|
||||
* Audio file converting: mpv --o=outfile.m4a infile.flac --no-video
|
||||
--oac=aac --oacopts=b=320k
|
||||
|
||||
What does not work yet
|
||||
======================
|
||||
|
||||
* 3-pass encoding (ensuring constant total size and bitrate constraints while
|
||||
having VBR audio; mencoder calls this "frameno")
|
||||
* Direct stream copy
|
170
mpv/.config/mpv/input.conf
Normal file
170
mpv/.config/mpv/input.conf
Normal file
@ -0,0 +1,170 @@
|
||||
# mpv keybindings
|
||||
#
|
||||
# Location of user-defined bindings: ~/.config/mpv/input.conf
|
||||
#
|
||||
# Lines starting with # are comments. Use SHARP to assign the # key.
|
||||
# Copy this file and uncomment and edit the bindings you want to change.
|
||||
#
|
||||
# List of commands and further details: DOCS/man/input.rst
|
||||
# List of special keys: --input-keylist
|
||||
# Keybindings testing mode: mpv --input-test --force-window --idle
|
||||
#
|
||||
# Use 'ignore' to unbind a key fully (e.g. 'ctrl+a ignore').
|
||||
#
|
||||
# Strings need to be quoted and escaped:
|
||||
# KEY show-text "This is a single backslash: \\ and a quote: \" !"
|
||||
#
|
||||
# You can use modifier-key combinations like Shift+Left or Ctrl+Alt+x with
|
||||
# the modifiers Shift, Ctrl, Alt and Meta (may not work on the terminal).
|
||||
#
|
||||
# The default keybindings are hardcoded into the mpv binary.
|
||||
# You can disable them completely with: --no-input-default-bindings
|
||||
|
||||
# Developer note:
|
||||
# On compilation, this file is baked into the mpv binary, and all lines are
|
||||
# uncommented (unless '#' is followed by a space) - thus this file defines the
|
||||
# default key bindings.
|
||||
|
||||
# If this is enabled, treat all the following bindings as default.
|
||||
#default-bindings start
|
||||
|
||||
#MBTN_LEFT ignore # don't do anything
|
||||
MBTN_LEFT_DBL cycle fullscreen # toggle fullscreen
|
||||
MBTN_RIGHT cycle pause # toggle pause/playback mode
|
||||
#MBTN_BACK playlist-prev # skip to the previous file
|
||||
#MBTN_FORWARD playlist-next # skip to the next file
|
||||
|
||||
# Mouse wheels, touchpad or other input devices that have axes
|
||||
# if the input devices supports precise scrolling it will also scale the
|
||||
# numeric value accordingly
|
||||
WHEEL_UP add volume 2
|
||||
WHEEL_DOWN add volume -2
|
||||
#WHEEL_LEFT seek -10 # seek 10 seconds backward
|
||||
#WHEEL_RIGHT seek 10 # seek 10 seconds forward
|
||||
|
||||
## Seek units are in seconds, but note that these are limited by keyframes
|
||||
RIGHT seek 5 # seek 5 seconds forward
|
||||
LEFT seek -5 # seek 5 seconds backward
|
||||
#UP seek 60 # seek 1 minute forward
|
||||
#DOWN seek -60 # seek 1 minute backward
|
||||
# Do smaller, always exact (non-keyframe-limited), seeks with shift.
|
||||
# Don't show them on the OSD (no-osd).
|
||||
#Shift+RIGHT no-osd seek 1 exact # seek exactly 1 second forward
|
||||
#Shift+LEFT no-osd seek -1 exact # seek exactly 1 second backward
|
||||
#Shift+UP no-osd seek 5 exact # seek exactly 5 seconds forward
|
||||
#Shift+DOWN no-osd seek -5 exact # seek exactly 5 seconds backward
|
||||
#Ctrl+LEFT no-osd sub-seek -1 # seek to the previous subtitle
|
||||
#Ctrl+RIGHT no-osd sub-seek 1 # seek to the next subtitle
|
||||
#Ctrl+Shift+LEFT sub-step -1 # change subtitle timing such that the previous subtitle is displayed
|
||||
#Ctrl+Shift+RIGHT sub-step 1 # change subtitle timing such that the next subtitle is displayed
|
||||
#Alt+left add video-pan-x 0.1 # move the video right
|
||||
#Alt+right add video-pan-x -0.1 # move the video left
|
||||
#Alt+up add video-pan-y 0.1 # move the video down
|
||||
#Alt+down add video-pan-y -0.1 # move the video up
|
||||
#Alt++ add video-zoom 0.1 # zoom in
|
||||
#ZOOMIN add video-zoom 0.1 # zoom in
|
||||
#Alt+- add video-zoom -0.1 # zoom out
|
||||
#ZOOMOUT add video-zoom -0.1 # zoom out
|
||||
#Alt+BS set video-zoom 0 ; set video-pan-x 0 ; set video-pan-y 0 # reset zoom and pan settings
|
||||
#PGUP add chapter 1 # seek to the next chapter
|
||||
#PGDWN add chapter -1 # seek to the previous chapter
|
||||
#Shift+PGUP seek 600 # seek 10 minutes forward
|
||||
#Shift+PGDWN seek -600 # seek 10 minutes backward
|
||||
#[ multiply speed 1/1.1 # decrease the playback speed
|
||||
#] multiply speed 1.1 # increase the playback speed
|
||||
#{ multiply speed 0.5 # halve the playback speed
|
||||
#} multiply speed 2.0 # double the playback speed
|
||||
#BS set speed 1.0 # reset the speed to normal
|
||||
#Shift+BS revert-seek # undo the previous (or marked) seek
|
||||
#Shift+Ctrl+BS revert-seek mark # mark the position for revert-seek
|
||||
#q quit
|
||||
#Q quit-watch-later # exit and remember the playback position
|
||||
#q {encode} quit 4
|
||||
#ESC set fullscreen no # leave fullscreen
|
||||
#ESC {encode} quit 4
|
||||
#p cycle pause # toggle pause/playback mode
|
||||
#. frame-step # advance one frame and pause
|
||||
#, frame-back-step # go back by one frame and pause
|
||||
#SPACE cycle pause # toggle pause/playback mode
|
||||
#> playlist-next # skip to the next file
|
||||
#ENTER playlist-next # skip to the next file
|
||||
#< playlist-prev # skip to the previous file
|
||||
#O no-osd cycle-values osd-level 3 1 # toggle displaying the OSD on user interaction or always
|
||||
#o show-progress # show playback progress
|
||||
#P show-progress # show playback progress
|
||||
#i script-binding stats/display-stats # display information and statistics
|
||||
#I script-binding stats/display-stats-toggle # toggle displaying information and statistics
|
||||
#` script-binding console/enable # open the console
|
||||
#z add sub-delay -0.1 # shift subtitles 100 ms earlier
|
||||
#Z add sub-delay +0.1 # delay subtitles by 100 ms
|
||||
#x add sub-delay +0.1 # delay subtitles by 100 ms
|
||||
#ctrl++ add audio-delay 0.100 # change audio/video sync by delaying the audio
|
||||
#ctrl+- add audio-delay -0.100 # change audio/video sync by shifting the audio earlier
|
||||
#Shift+g add sub-scale +0.1 # increase the subtitle font size
|
||||
#Shift+f add sub-scale -0.1 # decrease the subtitle font size
|
||||
#9 add volume -2
|
||||
#/ add volume -2
|
||||
#0 add volume 2
|
||||
#* add volume 2
|
||||
m cycle mute # toggle mute
|
||||
#1 add contrast -1
|
||||
#2 add contrast 1
|
||||
#3 add brightness -1
|
||||
#4 add brightness 1
|
||||
#5 add gamma -1
|
||||
#6 add gamma 1
|
||||
#7 add saturation -1
|
||||
#8 add saturation 1
|
||||
#Alt+0 set current-window-scale 0.5 # halve the window size
|
||||
#Alt+1 set current-window-scale 1.0 # reset the window size
|
||||
#Alt+2 set current-window-scale 2.0 # double the window size
|
||||
#d cycle deinterlace # toggle the deinterlacing filter
|
||||
#r add sub-pos -1 # move subtitles up
|
||||
#R add sub-pos +1 # move subtitles down
|
||||
#t add sub-pos +1 # move subtitles down
|
||||
#v cycle sub-visibility # hide or show the subtitles Alt+v cycle secondary-sub-visibility # hide or show the secondary subtitles V cycle sub-ass-vsfilter-aspect-compat # toggle stretching SSA/ASS subtitles with anamorphic videos to match the historical renderer u cycle-values sub-ass-override "force" "yes" # toggle overriding SSA/ASS subtitle styles with the normal styles j cycle sub # switch subtitle track J cycle sub down # switch subtitle track backwards SHARP cycle audio # switch audio track _ cycle video # switch video track T cycle ontop # toggle placing the video on top of other windows f cycle fullscreen # toggle fullscreen s screenshot # take a screenshot of the video in its original resolution with subtitles S screenshot video # take a screenshot of the video in its original resolution without subtitles
|
||||
#Ctrl+s screenshot window # take a screenshot of the window with OSD and subtitles
|
||||
#Alt+s screenshot each-frame # automatically screenshot every frame; issue this command again to stop taking screenshots
|
||||
#w add panscan -0.1 # decrease panscan
|
||||
#W add panscan +0.1 # shrink black bars by cropping the video
|
||||
#e add panscan +0.1 # shrink black bars by cropping the video
|
||||
#A cycle-values video-aspect-override "16:9" "4:3" "2.35:1" "-1" # cycle the video aspect ratio ("-1" is the container aspect)
|
||||
#POWER quit
|
||||
#PLAY cycle pause # toggle pause/playback mode
|
||||
#PAUSE cycle pause # toggle pause/playback mode
|
||||
#PLAYPAUSE cycle pause # toggle pause/playback mode
|
||||
#PLAYONLY set pause no # unpause
|
||||
#PAUSEONLY set pause yes # pause
|
||||
#STOP quit
|
||||
#FORWARD seek 60 # seek 1 minute forward
|
||||
#REWIND seek -60 # seek 1 minute backward
|
||||
#NEXT playlist-next # skip to the next file
|
||||
#PREV playlist-prev # skip to the previous file
|
||||
#VOLUME_UP add volume 2
|
||||
#VOLUME_DOWN add volume -2
|
||||
#MUTE cycle mute # toggle mute
|
||||
#CLOSE_WIN quit
|
||||
#CLOSE_WIN {encode} quit 4
|
||||
#ctrl+w quit
|
||||
#E cycle edition # switch edition
|
||||
#l ab-loop # set/clear A-B loop points
|
||||
#L cycle-values loop-file "inf" "no" # toggle infinite looping
|
||||
#ctrl+c quit 4
|
||||
#DEL script-binding osc/visibility # cycle OSC visibility between never, auto (mouse-move) and always
|
||||
#ctrl+h cycle-values hwdec "auto-safe" "no" # toggle hardware decoding
|
||||
#F8 show-text ${playlist} # show the playlist
|
||||
#F9 show-text ${track-list} # show the list of video, audio and sub tracks
|
||||
|
||||
#
|
||||
# Legacy bindings (may or may not be removed in the future)
|
||||
#
|
||||
#! add chapter -1 # seek to the previous chapter
|
||||
#@ add chapter 1 # seek to the next chapter
|
||||
|
||||
#
|
||||
# Not assigned by default
|
||||
# (not an exhaustive list of unbound commands)
|
||||
#
|
||||
|
||||
# ? cycle sub-forced-events-only # display only DVD/PGS forced subtitle events
|
||||
# ? stop # stop playback (quit or enter idle mode)
|
93
mpv/.config/mpv/mplayer-input.conf
Normal file
93
mpv/.config/mpv/mplayer-input.conf
Normal file
@ -0,0 +1,93 @@
|
||||
##
|
||||
## MPlayer-style key bindings
|
||||
##
|
||||
## Save it as ~/.config/mpv/input.conf to use it.
|
||||
##
|
||||
## Generally, it's recommended to use this as reference-only.
|
||||
##
|
||||
|
||||
RIGHT seek +10
|
||||
LEFT seek -10
|
||||
DOWN seek -60
|
||||
UP seek +60
|
||||
PGUP seek 600
|
||||
PGDWN seek -600
|
||||
m cycle mute
|
||||
SHARP cycle audio # switch audio streams
|
||||
+ add audio-delay 0.100
|
||||
= add audio-delay 0.100
|
||||
- add audio-delay -0.100
|
||||
[ multiply speed 0.9091 # scale playback speed
|
||||
] multiply speed 1.1
|
||||
{ multiply speed 0.5
|
||||
} multiply speed 2.0
|
||||
BS set speed 1.0 # reset speed to normal
|
||||
q quit
|
||||
ESC quit
|
||||
ENTER playlist-next force # skip to next file
|
||||
p cycle pause
|
||||
. frame-step # advance one frame and pause
|
||||
SPACE cycle pause
|
||||
HOME set playlist-pos 0 # not the same as MPlayer
|
||||
#END pt_up_step -1
|
||||
> playlist-next # skip to next file
|
||||
< playlist-prev # previous
|
||||
#INS alt_src_step 1
|
||||
#DEL alt_src_step -1
|
||||
o osd
|
||||
I show-text "${filename}" # display filename in osd
|
||||
P show-progress
|
||||
z add sub-delay -0.1 # subtract 100 ms delay from subs
|
||||
x add sub-delay +0.1 # add
|
||||
9 add volume -1
|
||||
/ add volume -1
|
||||
0 add volume 1
|
||||
* add volume 1
|
||||
1 add contrast -1
|
||||
2 add contrast 1
|
||||
3 add brightness -1
|
||||
4 add brightness 1
|
||||
5 add hue -1
|
||||
6 add hue 1
|
||||
7 add saturation -1
|
||||
8 add saturation 1
|
||||
( add balance -0.1 # adjust audio balance in favor of left
|
||||
) add balance +0.1 # right
|
||||
d cycle framedrop
|
||||
D cycle deinterlace # toggle deinterlacer (auto-inserted filter)
|
||||
r add sub-pos -1 # move subtitles up
|
||||
t add sub-pos +1 # down
|
||||
#? sub-step +1 # immediately display next subtitle
|
||||
#? sub-step -1 # previous
|
||||
#? add sub-scale +0.1 # increase subtitle font size
|
||||
#? add sub-scale -0.1 # decrease subtitle font size
|
||||
f cycle fullscreen
|
||||
T cycle ontop # toggle video window ontop of other windows
|
||||
w add panscan -0.1 # zoom out with -panscan 0 -fs
|
||||
e add panscan +0.1 # in
|
||||
c cycle stream-capture # save (and append) file/stream to stream.dump with -capture
|
||||
s screenshot # take a screenshot (if you want PNG, use "--screenshot-format=png")
|
||||
S screenshot - each-frame # S will take a png screenshot of every frame
|
||||
|
||||
h cycle tv-channel 1
|
||||
l cycle tv-channel -1
|
||||
n cycle tv-norm
|
||||
#b tv_step_chanlist
|
||||
|
||||
#? add chapter -1 # skip to previous dvd chapter
|
||||
#? add chapter +1 # next
|
||||
|
||||
##
|
||||
## Advanced seek
|
||||
## Uncomment the following lines to be able to seek to n% of the media with
|
||||
## the Fx keys.
|
||||
##
|
||||
#F1 seek 10 absolute-percent
|
||||
#F2 seek 20 absolute-percent
|
||||
#F3 seek 30 absolute-percent
|
||||
#F4 seek 40 absolute-percent
|
||||
#F5 seek 50 absolute-percent
|
||||
#F6 seek 60 absolute-percent
|
||||
#F7 seek 70 absolute-percent
|
||||
#F8 seek 80 absolute-percent
|
||||
#F9 seek 90 absolute-percent
|
143
mpv/.config/mpv/mpv.conf
Normal file
143
mpv/.config/mpv/mpv.conf
Normal file
@ -0,0 +1,143 @@
|
||||
#
|
||||
# Example mpv configuration file
|
||||
#
|
||||
# Warning:
|
||||
#
|
||||
# The commented example options usually do _not_ set the default values. Call
|
||||
# mpv with --list-options to see the default values for most options. There is
|
||||
# no builtin or example mpv.conf with all the defaults.
|
||||
#
|
||||
#
|
||||
# Configuration files are read system-wide from /usr/local/etc/mpv.conf
|
||||
# and per-user from ~/.config/mpv/mpv.conf, where per-user settings override
|
||||
# system-wide settings, all of which are overridden by the command line.
|
||||
#
|
||||
# Configuration file settings and the command line options use the same
|
||||
# underlying mechanisms. Most options can be put into the configuration file
|
||||
# by dropping the preceding '--'. See the man page for a complete list of
|
||||
# options.
|
||||
#
|
||||
# Lines starting with '#' are comments and are ignored.
|
||||
#
|
||||
# See the CONFIGURATION FILES section in the man page
|
||||
# for a detailed description of the syntax.
|
||||
#
|
||||
# Profiles should be placed at the bottom of the configuration file to ensure
|
||||
# that settings wanted as defaults are not restricted to specific profiles.
|
||||
|
||||
##################
|
||||
# video settings #
|
||||
##################
|
||||
|
||||
# Start in fullscreen mode by default.
|
||||
#fs=yes
|
||||
|
||||
# force starting with centered window
|
||||
#geometry=50%:50%
|
||||
|
||||
# don't allow a new window to have a size larger than 90% of the screen size
|
||||
#autofit-larger=90%x90%
|
||||
|
||||
# Do not close the window on exit.
|
||||
#keep-open=yes
|
||||
|
||||
# Do not wait with showing the video window until it has loaded. (This will
|
||||
# resize the window once video is loaded. Also always shows a window with
|
||||
# audio.)
|
||||
#force-window=immediate
|
||||
|
||||
# Disable the On Screen Controller (OSC).
|
||||
#osc=no
|
||||
|
||||
# Keep the player window on top of all other windows.
|
||||
#ontop=yes
|
||||
|
||||
# Specify fast video rendering preset (for --vo=<gpu|gpu-next> only)
|
||||
# Recommended for mobile devices or older hardware with limited processing power
|
||||
#profile=fast
|
||||
|
||||
# Specify high quality video rendering preset (for --vo=<gpu|gpu-next> only)
|
||||
# Offers superior image fidelity and visual quality for an enhanced viewing
|
||||
# experience on capable hardware
|
||||
#profile=high-quality
|
||||
|
||||
# Force video to lock on the display's refresh rate, and change video and audio
|
||||
# speed to some degree to ensure synchronous playback - can cause problems
|
||||
# with some drivers and desktop environments.
|
||||
#video-sync=display-resample
|
||||
|
||||
# Enable hardware decoding if available. Often, this does not work with all
|
||||
# video outputs, but should work well with default settings on most systems.
|
||||
# If performance or energy usage is an issue, forcing the vdpau or vaapi VOs
|
||||
# may or may not help.
|
||||
#hwdec=auto
|
||||
|
||||
##################
|
||||
# audio settings #
|
||||
##################
|
||||
|
||||
# Specify default audio device. You can list devices with: --audio-device=help
|
||||
# The option takes the device string (the stuff between the '...').
|
||||
#audio-device=alsa/default
|
||||
|
||||
# Do not filter audio to keep pitch when changing playback speed.
|
||||
#audio-pitch-correction=no
|
||||
|
||||
# Output 5.1 audio natively, and upmix/downmix audio with a different format.
|
||||
#audio-channels=5.1
|
||||
# Disable any automatic remix, _if_ the audio output accepts the audio format.
|
||||
# of the currently played file. See caveats mentioned in the manpage.
|
||||
# (The default is "auto-safe", see manpage.)
|
||||
#audio-channels=auto
|
||||
|
||||
##################
|
||||
# other settings #
|
||||
##################
|
||||
|
||||
# Pretend to be a web browser. Might fix playback with some streaming sites,
|
||||
# but also will break with shoutcast streams.
|
||||
#user-agent="Mozilla/5.0"
|
||||
|
||||
# cache settings
|
||||
#
|
||||
# Use a large seekable RAM cache even for local input.
|
||||
#cache=yes
|
||||
#
|
||||
# Use extra large RAM cache (needs cache=yes to make it useful).
|
||||
#demuxer-max-bytes=500M
|
||||
#demuxer-max-back-bytes=100M
|
||||
#
|
||||
# Disable the behavior that the player will pause if the cache goes below a
|
||||
# certain fill size.
|
||||
#cache-pause=no
|
||||
#
|
||||
# Store cache payload on the hard disk instead of in RAM. (This may negatively
|
||||
# impact performance unless used for slow input such as network.)
|
||||
#cache-dir=~/.cache/
|
||||
#cache-on-disk=yes
|
||||
|
||||
# Display English subtitles if available.
|
||||
#slang=en
|
||||
|
||||
# Play Finnish audio if available, fall back to English otherwise.
|
||||
#alang=fi,en
|
||||
|
||||
# Change subtitle encoding. For Arabic subtitles use 'cp1256'.
|
||||
# If the file seems to be valid UTF-8, prefer UTF-8.
|
||||
# (You can add '+' in front of the codepage to force it.)
|
||||
#sub-codepage=cp1256
|
||||
|
||||
# You can also include other configuration files.
|
||||
#include=/path/to/the/file/you/want/to/include
|
||||
|
||||
############
|
||||
# Profiles #
|
||||
############
|
||||
|
||||
# The options declared as part of profiles override global default settings,
|
||||
# but only take effect when the profile is active.
|
||||
|
||||
# The following profile can be enabled on the command line with: --profile=eye-cancer
|
||||
|
||||
#[eye-cancer]
|
||||
#sharpen=5
|
59
mpv/.config/mpv/restore-old-bindings.conf
Normal file
59
mpv/.config/mpv/restore-old-bindings.conf
Normal file
@ -0,0 +1,59 @@
|
||||
|
||||
# This file contains all bindings that were removed after a certain release.
|
||||
# If you want MPlayer bindings, use mplayer-input.conf
|
||||
|
||||
# Pick the bindings you want back and add them to your own input.conf. Append
|
||||
# this file to your input.conf if you want them all back:
|
||||
#
|
||||
# cat restore-old-bindings.conf >> ~/.config/mpv/input.conf
|
||||
#
|
||||
# Older installations use ~/.mpv/input.conf instead.
|
||||
|
||||
# changed in mpv 0.37.0
|
||||
|
||||
WHEEL_UP seek 10 # seek 10 seconds forward
|
||||
WHEEL_DOWN seek -10 # seek 10 seconds backward
|
||||
WHEEL_LEFT add volume -2
|
||||
WHEEL_RIGHT add volume 2
|
||||
|
||||
# changed in mpv 0.27.0 (macOS and Wayland only)
|
||||
|
||||
# WHEEL_LEFT seek 5
|
||||
# WHEEL_RIGHT seek -5
|
||||
|
||||
# changed in mpv 0.26.0
|
||||
|
||||
H cycle dvbin-channel-switch-offset up
|
||||
K cycle dvbin-channel-switch-offset down
|
||||
|
||||
I show-text "${filename}" # display filename in osd
|
||||
|
||||
# changed in mpv 0.24.0
|
||||
|
||||
L cycle-values loop-playlist "inf" "no"
|
||||
|
||||
# changed in mpv 0.10.0
|
||||
|
||||
O osd
|
||||
D cycle deinterlace
|
||||
d cycle framedrop
|
||||
|
||||
# changed in mpv 0.7.0
|
||||
|
||||
ENTER playlist-next force
|
||||
|
||||
# changed in mpv 0.6.0
|
||||
|
||||
ESC quit
|
||||
|
||||
# changed in mpv 0.5.0
|
||||
|
||||
PGUP seek 600
|
||||
PGDWN seek -600
|
||||
RIGHT seek 10
|
||||
LEFT seek -10
|
||||
+ add audio-delay 0.100
|
||||
- add audio-delay -0.100
|
||||
F cycle sub-forced-events-only
|
||||
U stop
|
||||
o cycle-values osd-level
|
656
mpv/.config/mpv/tech-overview.txt
Normal file
656
mpv/.config/mpv/tech-overview.txt
Normal file
@ -0,0 +1,656 @@
|
||||
This file intends to give a big picture overview of how mpv is structured.
|
||||
|
||||
player/*.c:
|
||||
Essentially makes up the player applications, including the main() function
|
||||
and the playback loop.
|
||||
|
||||
Generally, it accesses all other subsystems, initializes them, and pushes
|
||||
data between them during playback.
|
||||
|
||||
The structure is as follows (as of commit e13c05366557cb):
|
||||
* main():
|
||||
* basic initializations (e.g. init_libav() and more)
|
||||
* pre-parse command line (verbosity level, config file locations)
|
||||
* load config files (parse_cfgfiles())
|
||||
* parse command line, add files from the command line to playlist
|
||||
(m_config_parse_mp_command_line())
|
||||
* check help options etc. (call handle_help_options()), possibly exit
|
||||
* call mp_play_files() function that works down the playlist:
|
||||
* run idle loop (idle_loop()), until there are files in the
|
||||
playlist or an exit command was given (only if --idle it set)
|
||||
* actually load and play a file in play_current_file():
|
||||
* run all the dozens of functions to load the file and
|
||||
initialize playback
|
||||
* run a small loop that does normal playback, until the file is
|
||||
done or a command terminates playback
|
||||
(on each iteration, run_playloop() is called, which is rather
|
||||
big and complicated - it decodes some audio and video on
|
||||
each frame, waits for input, etc.)
|
||||
* uninitialize playback
|
||||
* determine next entry on the playlist to play
|
||||
* loop, or exit if no next file or quit is requested
|
||||
(see enum stop_play_reason)
|
||||
* call mp_destroy()
|
||||
* run_playloop():
|
||||
* calls fill_audio_out_buffers()
|
||||
This checks whether new audio needs to be decoded, and pushes it
|
||||
to the AO.
|
||||
* calls write_video()
|
||||
Decode new video, and push it to the VO.
|
||||
* determines whether playback of the current file has ended
|
||||
* determines when to start playback after seeks
|
||||
* and calls a whole lot of other stuff
|
||||
(Really, this function does everything.)
|
||||
|
||||
Things worth saying about the playback core:
|
||||
- most state is in MPContext (core.h), which is not available to the
|
||||
subsystems (and should not be made available)
|
||||
- the currently played tracks are in mpctx->current_tracks, and decoder
|
||||
state in track.dec/d_sub
|
||||
- the other subsystems rarely call back into the frontend, and the frontend
|
||||
polls them instead (probably a good thing)
|
||||
- one exceptions are wakeup callbacks, which notify a "higher" component
|
||||
of a changed situation in a subsystem
|
||||
|
||||
I like to call the player/*.c files the "frontend".
|
||||
|
||||
ta.h & ta.c:
|
||||
Hierarchical memory manager inspired by talloc from Samba. It's like a
|
||||
malloc() with more features. Most importantly, each talloc allocation can
|
||||
have a parent, and if the parent is free'd, all children will be free'd as
|
||||
well. The parent is an arbitrary talloc allocation. It's either set by the
|
||||
allocation call by passing a talloc parent, usually as first argument to the
|
||||
allocation function. It can also be set or reset later by other calls (at
|
||||
least talloc_steal()). A talloc allocation that is used as parent is often
|
||||
called a talloc context.
|
||||
|
||||
One very useful feature of talloc is fast tracking of memory leaks. ("Fast"
|
||||
as in it doesn't require valgrind.) You can enable it by setting the
|
||||
MPV_LEAK_REPORT environment variable to "1":
|
||||
export MPV_LEAK_REPORT=1
|
||||
Or permanently by building with --enable-ta-leak-report.
|
||||
This will list all unfree'd allocations on exit.
|
||||
|
||||
Documentation can be found here:
|
||||
http://git.samba.org/?p=samba.git;a=blob;f=lib/talloc/talloc.h;hb=HEAD
|
||||
|
||||
For some reason, we're still using API-compatible wrappers instead of TA
|
||||
directly. The talloc wrapper has only a subset of the functionality, and
|
||||
in particular the wrappers abort() on memory allocation failure.
|
||||
|
||||
Note: unlike tcmalloc, jemalloc, etc., talloc() is not actually a malloc
|
||||
replacement. It works on top of system malloc and provides additional
|
||||
features that are supposed to make memory management easier.
|
||||
|
||||
player/command.c:
|
||||
This contains the implementation for client API commands and properties.
|
||||
Properties are essentially dynamic variables changed by certain commands.
|
||||
This is basically responsible for all user commands, like initiating
|
||||
seeking, switching tracks, etc. It calls into other player/*.c files,
|
||||
where most of the work is done, but also calls other parts of mpv.
|
||||
|
||||
player/core.h:
|
||||
Data structures and function prototypes for most of player/*.c. They are
|
||||
usually not accessed by other parts of mpv for the sake of modularization.
|
||||
|
||||
player/client.c:
|
||||
This implements the client API (libmpv/client.h). For the most part, this
|
||||
just calls into other parts of the player. This also manages a ringbuffer
|
||||
of events from player to clients.
|
||||
|
||||
options/options.h, options/options.c
|
||||
options.h contains the global option struct MPOpts. The option declarations
|
||||
(option names, types, and MPOpts offsets for the option parser) are in
|
||||
options.c. Most default values for options and MPOpts are in
|
||||
mp_default_opts at the end of options.c.
|
||||
|
||||
MPOpts is unfortunately quite monolithic, but is being incrementally broken
|
||||
up into sub-structs. Many components have their own sub-option structs
|
||||
separate from MPOpts. New options should be bound to the component that uses
|
||||
them. Add a new option table/struct if needed.
|
||||
|
||||
The global MPOpts still contains the sub-structs as fields, which serves to
|
||||
link them to the option parser. For example, an entry like this may be
|
||||
typical:
|
||||
|
||||
{"", OPT_SUBSTRUCT(demux_opts, demux_conf)},
|
||||
|
||||
This directs the option access code to include all options in demux_conf
|
||||
into the global option list, with no prefix (""), and as part of the
|
||||
MPOpts.demux_opts field. The MPOpts.demux_opts field is actually not
|
||||
accessed anywhere, and instead demux.c does this:
|
||||
|
||||
struct m_config_cache *opts_cache =
|
||||
m_config_cache_alloc(demuxer, global, &demux_conf);
|
||||
struct demux_opts *opts = opts_cache->opts;
|
||||
|
||||
... to get a copy of its options.
|
||||
|
||||
See m_config.h (below) how to access options.
|
||||
|
||||
The actual option parser is spread over m_option.c, m_config.c, and
|
||||
parse_commandline.c, and uses the option table in options.c.
|
||||
|
||||
options/m_config.h & m_config.c:
|
||||
Code for querying and managing options. This (unfortunately) contains both
|
||||
declarations for the "legacy-ish" global m_config struct, and ways to access
|
||||
options in a threads-safe way anywhere, like m_config_cache_alloc().
|
||||
|
||||
m_config_cache_alloc() lets anyone read, observe, and write options in any
|
||||
thread. The only state it needs is struct mpv_global, which is an opaque
|
||||
type that can be passed "down" the component hierarchy. For safety reasons,
|
||||
you should not pass down any pointers to option structs (like MPOpts), but
|
||||
instead pass down mpv_global, and use m_config_cache_alloc() (or similar)
|
||||
to get a synchronized copy of the options.
|
||||
|
||||
input/input.c:
|
||||
This translates keyboard input coming from VOs and other sources (such
|
||||
as remote control devices like Apple IR or client API commands) to the
|
||||
key bindings listed in the user's (or the builtin) input.conf and turns
|
||||
them into items of type struct mp_cmd. These commands are queued, and read
|
||||
by playloop.c. They get pushed with run_command() to command.c.
|
||||
|
||||
Note that keyboard input and commands used by the client API are the same.
|
||||
The client API only uses the command parser though, and has its own queue
|
||||
of input commands somewhere else.
|
||||
|
||||
common/msg.h:
|
||||
All terminal output must go through mp_msg().
|
||||
|
||||
stream/*:
|
||||
File input is implemented here. stream.h/.c provides a simple stream based
|
||||
interface (like reading a number of bytes at a given offset). mpv can
|
||||
also play from http streams and such, which is implemented here.
|
||||
|
||||
E.g. if mpv sees "http://something" on the command line, it will pick
|
||||
stream_lavf.c based on the prefix, and pass the rest of the filename to it.
|
||||
|
||||
Some stream inputs are quite special: stream_dvd.c turns DVDs into mpeg
|
||||
streams (DVDs are actually a bunch of vob files etc. on a filesystem),
|
||||
stream_tv.c provides TV input including channel switching.
|
||||
|
||||
Some stream inputs are just there to invoke special demuxers, like
|
||||
stream_mf.c. (Basically to make the prefix "mf://" do something special.)
|
||||
|
||||
demux/:
|
||||
Demuxers split data streams into audio/video/sub streams, which in turn
|
||||
are split in packets. Packets (see demux_packet.h) are mostly byte chunks
|
||||
tagged with a playback time (PTS). These packets are passed to the decoders.
|
||||
|
||||
Most demuxers have been removed from this fork, and the only important and
|
||||
"actual" demuxers left are demux_mkv.c and demux_lavf.c (uses libavformat).
|
||||
There are some pseudo demuxers like demux_cue.c.
|
||||
|
||||
The main interface is in demux.h. The stream headers are in stheader.h.
|
||||
There is a stream header for each audio/video/sub stream, and each of them
|
||||
holds codec information about the stream and other information.
|
||||
|
||||
demux.c is a bit big, the main reason being that it contains the demuxer
|
||||
cache, which is implemented as a list of packets. The cache is complex
|
||||
because it support seeking, multiple ranges, prefetching, and so on.
|
||||
|
||||
video/:
|
||||
This contains several things related to audio/video decoding, as well as
|
||||
video filters.
|
||||
|
||||
mp_image.h and img_format.h define how mpv stores decoded video frames
|
||||
internally.
|
||||
|
||||
video/decode/:
|
||||
vd_*.c are video decoders. (There's only vd_lavc.c left.) dec_video.c
|
||||
handles most of connecting the frontend with the actual decoder.
|
||||
|
||||
video/filter/:
|
||||
vf_*.c and vf.c form the video filter chain. They are fed by the video
|
||||
decoder, and output the filtered images to the VOs though vf_vo.c. By
|
||||
default, no video filters (except vf_vo) are used. vf_scale is automatically
|
||||
inserted if the video output can't handle the video format used by the
|
||||
decoder.
|
||||
|
||||
video/out/:
|
||||
Video output. They also create GUI windows and handle user input. In most
|
||||
cases, the windowing code is shared among VOs, like x11_common.c for X11 and
|
||||
w32_common.c for Windows. The VOs stand between frontend and windowing code.
|
||||
vo_gpu can pick a windowing system at runtime, e.g. the same binary can
|
||||
provide both X11 and Cocoa support on OSX.
|
||||
|
||||
VOs can be reconfigured at runtime. A vo_reconfig() call can change the video
|
||||
resolution and format, without destroying the window.
|
||||
|
||||
vo_gpu should be taken as reference.
|
||||
|
||||
audio/:
|
||||
format.h/format.c define the uncompressed audio formats. (As well as some
|
||||
compressed formats used for spdif.)
|
||||
|
||||
audio/decode/:
|
||||
ad_*.c and dec_audio.c handle audio decoding. ad_lavc.c is the
|
||||
decoder using ffmpeg. ad_spdif.c is not really a decoder, but is used for
|
||||
compressed audio passthrough.
|
||||
|
||||
audio/filter/:
|
||||
Audio filter chain. af_lavrresample is inserted if any form of conversion
|
||||
between audio formats is needed.
|
||||
|
||||
audio/out/:
|
||||
Audio outputs.
|
||||
|
||||
Unlike VOs, AOs can't be reconfigured on a format change. On audio format
|
||||
changes, the AO will simply be closed and re-opened.
|
||||
|
||||
There are wrappers to support for two types of audio APIs: push.c and
|
||||
pull.c. ao.c calls into one of these. They contain generic code to deal
|
||||
with the data flow these APIs impose.
|
||||
|
||||
Note that mpv synchronizes the video to the audio. That's the reason
|
||||
why buggy audio drivers can have a bad influence on playback quality.
|
||||
|
||||
sub/:
|
||||
Contains subtitle and OSD rendering.
|
||||
|
||||
osd.c/.h is actually the OSD code. It queries dec_sub.c to retrieve
|
||||
decoded/rendered subtitles. osd_libass.c is the actual implementation of
|
||||
the OSD text renderer (which uses libass, and takes care of all the tricky
|
||||
fontconfig/freetype API usage and text layouting).
|
||||
|
||||
The VOs call osd.c to render OSD and subtitle (via e.g. osd_draw()). osd.c
|
||||
in turn asks dec_sub.c for subtitle overlay bitmaps, which relays the
|
||||
request to one of the sd_*.c subtitle decoders/renderers.
|
||||
|
||||
Subtitle loading is in demux/. The MPlayer subreader.c is mostly gone - parts
|
||||
of it survive in demux_subreader.c. It's used as last fallback, or to handle
|
||||
some text subtitle types on Libav. It should go away eventually. Normally,
|
||||
subtitles are loaded via demux_lavf.c.
|
||||
|
||||
The subtitles are passed to dec_sub.c and the subtitle decoders in sd_*.c
|
||||
as they are demuxed. All text subtitles are rendered by sd_ass.c. If text
|
||||
subtitles are not in the ASS format, the libavcodec subtitle converters are
|
||||
used (lavc_conv.c).
|
||||
|
||||
Text subtitles can be preloaded, in which case they are read fully as soon
|
||||
as the subtitle is selected. In this case, they are effectively stored in
|
||||
sd_ass.c's internal state.
|
||||
|
||||
etc/:
|
||||
The file input.conf is actually integrated into the mpv binary by the
|
||||
build system. It contains the default keybindings.
|
||||
|
||||
Best practices and Concepts within mpv
|
||||
======================================
|
||||
|
||||
General contribution etc.
|
||||
-------------------------
|
||||
|
||||
See: DOCS/contribute.md
|
||||
|
||||
Error checking
|
||||
--------------
|
||||
|
||||
If an error is relevant, it should be handled. If it's interesting, log the
|
||||
error. However, mpv often keeps errors silent and reports failures somewhat
|
||||
coarsely by propagating them upwards the caller chain. This is OK, as long as
|
||||
the errors are not very interesting, or would require a developer to debug it
|
||||
anyway (in which case using a debugger would be more convenient, and the
|
||||
developer would need to add temporary debug printfs to get extremely detailed
|
||||
information which would not be appropriate during normal operation).
|
||||
|
||||
Basically, keep a balance on error reporting. But always check them, unless you
|
||||
have a good argument not to.
|
||||
|
||||
Memory allocation errors (OOM) are a special class of errors. Normally such
|
||||
allocation failures are not handled "properly". Instead, abort() is called.
|
||||
(New code should use MP_HANDLE_OOM() for this.) This is done out of laziness and
|
||||
for convenience, and due to the fact that MPlayer/mplayer2 never handled it
|
||||
correctly. (MPlayer varied between handling it correctly, trying to do so but
|
||||
failing, and just not caring, while mplayer2 started using abort() for it.)
|
||||
|
||||
This is justifiable in a number of ways. Error handling paths are notoriously
|
||||
untested and buggy, so merely having them won't make your program more reliable.
|
||||
Having these error handling paths also complicates non-error code, due to the
|
||||
need to roll back state at any point after a memory allocation.
|
||||
|
||||
Take any larger body of code, that is supposed to handle OOM, and test whether
|
||||
the error paths actually work, for example by overriding malloc with a version
|
||||
that randomly fails. You will find bugs quickly, and often they will be very
|
||||
annoying to fix (if you can even reproduce them).
|
||||
|
||||
In addition, a clear indication that something went wrong may be missing. On
|
||||
error your program may exhibit "degraded" behavior by design. Consider a video
|
||||
encoder dropping frames somewhere in the middle of a video due to temporary
|
||||
allocation failures, instead of just exiting with an errors. In other cases, it
|
||||
may open conceptual security holes. Failing fast may be better.
|
||||
|
||||
mpv uses GPU APIs, which may be break on allocation errors (because driver
|
||||
authors will have the same issues as described here), or don't even have a real
|
||||
concept for dealing with OOM (OpenGL).
|
||||
|
||||
libmpv is often used by GUIs, which I predict always break if OOM happens.
|
||||
|
||||
Last but not least, OSes like Linux use "overcommit", which basically means that
|
||||
your program may crash any time OOM happens, even if it doesn't use malloc() at
|
||||
all!
|
||||
|
||||
But still, don't just assume malloc() always succeeds. Use MP_HANDLE_OOM(). The
|
||||
ta* APIs do this for you. The reason for this is that dereferencing a NULL
|
||||
pointer can have security relevant consequences if large offsets are involved.
|
||||
Also, a clear error message is better than a random segfault.
|
||||
|
||||
Some big memory allocations are checked anyway. For example, all code must
|
||||
assume that allocating video frames or packets can fail. (The above example
|
||||
of dropping video frames during encoding is entirely possible in mpv.)
|
||||
|
||||
Undefined behavior
|
||||
------------------
|
||||
|
||||
Undefined behavior (UB) is a concept in the C language. C is famous for being a
|
||||
language that makes it almost impossible to write working code, because
|
||||
undefined behavior is so easily triggered, compilers will happily abuse it to
|
||||
generate "faster" code, debugging tools will shout at you, and sometimes it
|
||||
even means your code doesn't work.
|
||||
|
||||
There is a lot of literature on this topic. Read it.
|
||||
|
||||
(In C's defense, UB exists in other languages too, but since they're not used
|
||||
for low level infrastructure, and/or these languages are at times not rigorously
|
||||
defined, simply nobody cares. However, the C standard committee is still guilty
|
||||
for not addressing this. I'll admit that I can't even tell from the standard's
|
||||
gibberish whether some specific behavior is UB or not. It's written like tax
|
||||
law.)
|
||||
|
||||
In mpv, we generally try to avoid undefined behavior. For one, we want portable
|
||||
and reliable operation. But more importantly, we want clean output from
|
||||
debugging tools, in order to find real bugs more quickly and effectively.
|
||||
|
||||
Avoid the "works in practice" argument. Once debugging tools come into play, or
|
||||
simply when "in practice" stops being true, this will all get back to you in a
|
||||
bad way.
|
||||
|
||||
Global state, library safety
|
||||
----------------------------
|
||||
|
||||
Mutable global state is when code uses global variables that are not read-only.
|
||||
This must be avoided in mpv. Always use context structs that the caller of
|
||||
your code needs to allocate, and whose pointers are passed to your functions.
|
||||
|
||||
Library safety means that your code (or library) can be used by a library
|
||||
without causing conflicts with other library users in the same process. To any
|
||||
piece of code, a "safe" library's API can simply be used, without having to
|
||||
worry about other API users that may be around somewhere.
|
||||
|
||||
Libraries are often not library safe, because they use global mutable state
|
||||
or other "global" resources. Typical examples include use of signals, simple
|
||||
global variables (like hsearch() in libc), or internal caches not protected by
|
||||
locks.
|
||||
|
||||
A surprisingly high number of libraries are not library safe because they need
|
||||
global initialization. Typically they provide an API function, which
|
||||
"initializes" the library, and which must be called before calling any other
|
||||
API functions. Often, you are to provide global configuration parameters, which
|
||||
can change the behavior of the library. If two libraries A and B use library C,
|
||||
but A and B initialize C with different parameters, something "bad" may happen.
|
||||
In addition, these global initialization functions are often not thread-safe. So
|
||||
if A and B try to initialize C at the same time (from different threads and
|
||||
without knowing about each other), it may cause undefined behavior. (libcurl is
|
||||
a good example of both of these issues. FFmpeg and some TLS libraries used to be
|
||||
affected, but improved.)
|
||||
|
||||
This is so bad because library A and B from the previous example most likely
|
||||
have no way to cooperate, because they're from different authors and have no
|
||||
business knowing each others. They'd need a library D, which wraps library C
|
||||
in a safe way. Unfortunately, typically something worse happens: libraries get
|
||||
"infected" by the unsafeness of its sub-libraries, and export a global init API
|
||||
just to initialize the sub-libraries. In the previous example, libraries A and B
|
||||
would export global init APIs just to init library C, even though the rest of
|
||||
A/B are clean and library safe. (Again, libcurl is an example of this, if you
|
||||
subtract other historic anti-features.)
|
||||
|
||||
The main problem with library safety is that its lack propagates to all
|
||||
libraries using the library.
|
||||
|
||||
We require libmpv to be library safe. This is not really possible, because some
|
||||
libraries are not library safe (FFmpeg, Xlib, partially ALSA). However, for
|
||||
ideological reasons, there is no global init API, and best effort is made to try
|
||||
to avoid problems.
|
||||
|
||||
libmpv has some features that are not library safe, but which are disabled by
|
||||
default (such as terminal usage aka stdout, or JSON IPC blocking SIGPIPE for
|
||||
internal convenience).
|
||||
|
||||
A notable, very disgustingly library unsafe behavior of libmpv is calling
|
||||
abort() on some memory allocation failure. See error checking section.
|
||||
|
||||
Logging
|
||||
-------
|
||||
|
||||
All logging and terminal output in mpv goes through the functions and macros
|
||||
provided in common/msg.h. This is in part for library safety, and in part to
|
||||
make sure users can silence all output, or to redirect the output elsewhere,
|
||||
like a log file or the internal console.lua script.
|
||||
|
||||
Locking
|
||||
-------
|
||||
|
||||
See generally available literature. In mpv, we use mp_thread for this.
|
||||
|
||||
Always keep locking clean. Don't skip locking just because it will work "in
|
||||
practice". (See undefined behavior section.) If your use case is simple, you may
|
||||
use C11 atomics, but most likely you will only hurt yourself and others.
|
||||
|
||||
Always make clear which fields in a struct are protected by which lock. If a
|
||||
field is immutable, or simply not thread-safe (e.g. state for a single worker
|
||||
thread), document it as well.
|
||||
|
||||
Internal mpv APIs are assumed to be not thread-safe by default. If they have
|
||||
special guarantees (such as being usable by more than one thread at a time),
|
||||
these should be explicitly documented.
|
||||
|
||||
All internal mpv APIs must be free of global state. Even if a component is not
|
||||
thread-safe, multiple threads can use _different_ instances of it without any
|
||||
locking.
|
||||
|
||||
On a side note, recursive locks may seem convenient at first, but introduce
|
||||
additional problems with condition variables and locking hierarchies. They
|
||||
should be avoided.
|
||||
|
||||
Locking hierarchy
|
||||
-----------------
|
||||
|
||||
A simple way to avoid deadlocks with classic locking is to define a locking
|
||||
hierarchy or lock order. If all threads acquire locks in the same order, no
|
||||
deadlocks will happen.
|
||||
|
||||
For example, a "leaf" lock is a lock that is below all other locks in the
|
||||
hierarchy. You can acquire it any time, as long as you don't acquire other
|
||||
locks while holding it.
|
||||
|
||||
Unfortunately, C has no way to declare or check the lock order, so you should at
|
||||
least document it.
|
||||
|
||||
In addition, try to avoid exposing locks to the outside. Making the declaration
|
||||
of a lock private to a specific .c file (and _not_ exporting accessors or
|
||||
lock/unlock functions that manipulate the lock) is a good idea. Your component's
|
||||
API may acquire internal locks, but should release them when returning. Keeping
|
||||
the entire locking in a single file makes it easy to check it.
|
||||
|
||||
Avoiding callback hell
|
||||
----------------------
|
||||
|
||||
mpv code is separated in components, like the "frontend" (i.e. MPContext mpctx),
|
||||
VOs, AOs, demuxers, and more. The frontend usually calls "down" the usage
|
||||
hierarchy: mpctx almost on top, then things like vo/ao, and utility code on the
|
||||
very bottom.
|
||||
|
||||
"Callback hell" is when components call both up and down the hierarchy,
|
||||
which for example leads to accidentally recursion, reentrancy problems, or
|
||||
locking nightmares. This is avoided by (mostly) calling only down the hierarchy.
|
||||
Basically the call graph forms a DAG. The other direction is handled by event
|
||||
queues, wakeup callbacks, and similar mechanisms.
|
||||
|
||||
Typically, a component provides an API, and does not know anything about its
|
||||
user. The API user (component higher in the hierarchy) polls the state of the
|
||||
lower component when needed.
|
||||
|
||||
This also enforces some level of modularization, and with some luck the locking
|
||||
hierarchy. (Basically, locks of lower components automatically become leaf
|
||||
locks.) Another positive effect is simpler memory management.
|
||||
|
||||
(Also see e.g.: http://250bpm.com/blog:24)
|
||||
|
||||
Wakeup callbacks
|
||||
----------------
|
||||
|
||||
This is a common concept in mpv. Even the public API uses it. It's used when an
|
||||
API has internal threads (or otherwise triggers asynchronous events), but the
|
||||
component call hierarchy needs to be kept. The wakeup callback is the only
|
||||
exception to the call hierarchy, and always calls up.
|
||||
|
||||
For example, vo spawns a thread that the API user (the mpv frontend) does not
|
||||
need to know about. vo simply provides a single-threaded API (or that looks like
|
||||
one). This API needs a way to notify the API user of new events. But the vo
|
||||
event producer is on the vo thread - it can't simply invoke a callback back into
|
||||
the API user, because then the API user has to deal with locking, despite not
|
||||
using threads. In addition, this will probably cause problems like mentioned in
|
||||
the "callback hell" section, especially lock order issues.
|
||||
|
||||
The solution is the wakeup callback. It merely unblocks the API user from
|
||||
waiting, and the API user then uses the normal vo API to examine whether or
|
||||
which state changed. As a concept, it documents what a wakeup callback is
|
||||
allowed to do and what not, to avoid the aforementioned problems.
|
||||
|
||||
Generally, you are not allowed to call any API from the wakeup callback. You
|
||||
just do whatever is needed to unblock your thread. For example, if it's waiting
|
||||
on a mutex/condition variable, acquire the mutex, set a change flag, signal
|
||||
the condition variable, unlock, return. (This mutex must not be held when
|
||||
calling the API. It must be a leaf lock.)
|
||||
|
||||
Restricting the wakeup callback like this sidesteps any reentrancy issues and
|
||||
other complexities. The API implementation can simply hold internal (and
|
||||
non-recursive) locks while invoking the wakeup callback.
|
||||
|
||||
The API user still needs to deal with locking (probably), but there's only the
|
||||
need to implement a single "receiver", that can handle the entire API of the
|
||||
used component. (Or multiple APIs - MPContext for example has only 1 wakeup
|
||||
callback that handles all AOs, VOs, input, demuxers, and more. It simple re-runs
|
||||
the playloop.)
|
||||
|
||||
You could get something more advanced by turning this into a message queue. The
|
||||
API would append a message to the queue, and the API user can read it. But then
|
||||
you still need a way to "wakeup" the API user (unless you force the API user
|
||||
to block on your API, which will make things inconvenient for the API user). You
|
||||
also need to worry about what happens if the message queue overruns (you either
|
||||
lose messages or have unbounded memory usage). In the mpv public API, the
|
||||
distinction between message queue and wakeup callback is sort of blurry, because
|
||||
it does provide a message queue, but an additional wakeup callback, so API
|
||||
users are not required to call mpv_wait_event() with a high timeout.
|
||||
|
||||
mpv itself prefers using wakeup callbacks over a generic event queue, because
|
||||
most times an event queue is not needed (or complicates things), and it is
|
||||
better to do it manually.
|
||||
|
||||
(You could still abstract the API user side of wakeup callback handling, and
|
||||
avoid reimplementing it all the time. Although mp_dispatch_queue already
|
||||
provides mechanisms for this.)
|
||||
|
||||
Condition variables
|
||||
-------------------
|
||||
|
||||
They're used whenever a thread needs to wait for something, without nonsense
|
||||
like sleep calls or busy waiting. mpv uses the mp_thread API for this.
|
||||
There's a lot of literature on condition variables, threading in general. Read it.
|
||||
|
||||
For initial understanding, it may be helpful to know that condition variables
|
||||
are not variables that signal a condition. mp_cond does not have any
|
||||
state per-se. Maybe mp_cond would better be named mp_interrupt,
|
||||
because its sole purpose is to interrupt a thread waiting via mp_cond_wait()
|
||||
(or similar). The "something" in "waiting for something" can be called
|
||||
predicate (to avoid confusing it with "condition"). Consult literature for the
|
||||
proper terms.
|
||||
|
||||
The very short version is...
|
||||
|
||||
Shared declarations:
|
||||
|
||||
mp_mutex lock;
|
||||
mp_cond cond_var;
|
||||
struct something state_var; // protected by lock, changes signaled by cond_var
|
||||
|
||||
Waiter thread:
|
||||
|
||||
mp_mutex_lock(&lock);
|
||||
|
||||
// Wait for a change in state_var. We want to wait until predicate_fulfilled()
|
||||
// returns true.
|
||||
// Must be a loop for 2 reasons:
|
||||
// 1. cond_var may be associated with other conditions too
|
||||
// 2. mp_cond_wait() can have sporadic wakeups
|
||||
while (!predicate_fulfilled(&state_var)) {
|
||||
// This unlocks, waits for cond_var to be signaled, and then locks again.
|
||||
// The _whole_ point of cond_var is that unlocking and waiting for the
|
||||
// signal happens atomically.
|
||||
mp_cond_wait(&cond_var, &lock);
|
||||
}
|
||||
|
||||
// Here you may react to the state change. The state cannot change
|
||||
// asynchronously as long as you still hold the lock (and didn't release
|
||||
// and reacquire it).
|
||||
// ...
|
||||
|
||||
mp_mutex_unlock(&lock);
|
||||
|
||||
Signaler thread:
|
||||
|
||||
mp_mutex_lock(&lock);
|
||||
|
||||
// Something changed. Update the shared variable with the new state.
|
||||
update_state(&state_var);
|
||||
|
||||
// Notify that something changed. This will wake up the waiter thread if
|
||||
// it's blocked in mp_cond_wait(). If not, nothing happens.
|
||||
mp_cond_broadcast(&cond_var);
|
||||
|
||||
// Fun fact: good implementations wake up the waiter only when the lock is
|
||||
// released, to reduce kernel scheduling overhead.
|
||||
mp_mutex_unlock(&lock);
|
||||
|
||||
Some basic rules:
|
||||
1. Always access your state under proper locking
|
||||
2. Always check your predicate before every call to mp_cond_wait()
|
||||
(And don't call mp_cond_wait() if the predicate is fulfilled.)
|
||||
3. Always call mp_cond_wait() in a loop
|
||||
(And only if your predicate failed without releasing the lock..)
|
||||
4. Always call mp_cond_broadcast()/_signal() inside of its associated
|
||||
lock
|
||||
|
||||
mpv sometimes violates rule 3, and leaves "retrying" (i.e. looping) to the
|
||||
caller.
|
||||
|
||||
Common pitfalls:
|
||||
- Thinking that mp_cond is some kind of semaphore, or holds any
|
||||
application state or the user predicate (it _only_ wakes up threads
|
||||
that are at the same time blocking on mp_cond_wait() and friends,
|
||||
nothing else)
|
||||
- Changing the predicate, but not updating all mp_cond_broadcast()/
|
||||
_signal() calls correctly
|
||||
- Forgetting that mp_cond_wait() unlocks the lock (other threads can
|
||||
and must acquire the lock)
|
||||
- Holding multiple nested locks while trying to wait (=> deadlock, violates
|
||||
the lock order anyway)
|
||||
- Waiting for a predicate correctly, but unlocking/relocking before acting
|
||||
on it (unlocking allows arbitrary state changes)
|
||||
- Confusing which lock/condition var. is used to manage a bit of state
|
||||
|
||||
Generally available literature probably has better examples and explanations.
|
||||
|
||||
Using condition variables the proper way is generally preferred over using more
|
||||
messy variants of them. (Just saying because on win32, "SetEvent" exists, and
|
||||
it's inferior to condition variables. Try to avoid the win32 primitives, even if
|
||||
you're dealing with Windows-only code.)
|
||||
|
||||
Threads
|
||||
-------
|
||||
|
||||
Threading should be conservatively used. Normally, mpv code pretends to be
|
||||
single-threaded, and provides thread-unsafe APIs. Threads are used coarsely,
|
||||
and if you can avoid messing with threads, you should. For example, VOs and AOs
|
||||
do not need to deal with threads normally, even though they run on separate
|
||||
threads. The glue code "isolates" them from any threading issues.
|
Loading…
Reference in New Issue
Block a user