wm4
cc8759a855
This fixes weird behavior in the following case: - open a file - make sure the max. demuxer forward cache is smaller than the file's video track - make sure the max. readahead duration is larger than the file's duration - disable the audio track - seek to the beginning of the file - once the cache has filled enable the audio track - a queue overflow warning should appear (- looking at the seek ranges is also interesting) The queue overflow warning happens because the packed queue for the video track will use up the full quota set by --demuxer-max-bytes. When the audio track is enabled, reading an audio packet would technically overflow the packet cache by the size of whatever packet is read next. This means the demuxer signals EOF to the decoder, and once playback has consumed enough video packets so that audio packets can be read again, the decoder resumes from EOF. This interacts badly with A/V synchronization and the whole thing can randomly crap itself until audio has fully recovered. We didn't care about this so far, but we want to raise the readahead duration to something very high, so that the demuxer cache is fully used. This means this case can be hit quite quickly by switching audio or subtitle tracks, and is not really an obscure corner case anymore. Fix this by always losing all cache. Since the cache can't be used anyway until the newly selected track has been read, this is not much of a disadvantage. The only thing that could be brought up is that unselecting the track again could resume operation normally. (Maybe this would be useful if network died completely without chance of recovery. Then you could watch the already buffered video anyway by deselecting the audio track again.) But given the headaches, this seems like the better solution. Unfortunately this requires adding new new strange fields and strangely fragmenting state management functions again. I'm sure whoever works on this in the future will hate me. Currently it seems like the lesser evil, and much simpler and robust than the other potential solutions. In case this needs to be revisited, here is a reminder for readers from the future what alternative solutions were considered, without those disadvantages: A first attempted solution allowed the demuxer to buffer some additional packets on track switching. This would allow it to read enough data to feed the decoder at least. But it was still awkward, as it didn't allow the demuxer to continue prefetching the newly selected track. It also barely worked, because you could make the forward buffer "over full" by seeking back with seekable cache enabled, and then it couldn't read packets anyway. As alternative solution, we could always demux and cache all tracks, even if they're deselected. This would also not require a network-level seek for the "refresh" logic (it's the thing that lets the video decoder continue as if nothing happened, while actually seeking back in the stream to get the missing audio packets, in the case of enabling a previously disabled audio track). But it would also possibly waste network and memory resources, depending on what the user actually wants. A second solution would just account the queue sizes for each stream separately. We could freely fill up the audio packet queue, even if the video queue is full. Since the demuxer API returns interleaved packets and doesn't let you predict which packet type comes next, this is not as simple as it sounds, but it'd probably tie in nicely with the "refresh" logic. A third solution would be removing buffered video packets from the end of the packet queue. Since the "refresh" logic gets these anyway, there is no reason to keep them if they prevent the audio packet queue from catching up with the video one. But this would require additional logic, would interact badly with a bunch of other corner cases. And as far as the code goes, it's rather complex, because all the logic is written with FIFO behavior in mind (including the fact that the packet queue is a singly linked list with no backwards links, making removal from the end harder).
mpv
- External links
- Overview
- System requirements
- Downloads
- Changelog
- Compilation
- FFmpeg vs. Libav
- FFmpeg ABI compatibility
- Release cycle
- Bug reports
- Contributing
- Relation to MPlayer and mplayer2
- License
- Contact
External links
Overview
mpv is a media player based on MPlayer and mplayer2. It supports a wide variety of video file formats, audio and video codecs, and subtitle types.
Releases can be found on the release list.
System requirements
- A not too ancient Linux, Windows 7 or later, or OSX 10.8 or later.
- A somewhat capable CPU. Hardware decoding might help if the CPU is too slow to
decode video in realtime, but must be explicitly enabled with the
--hwdecoption. - A not too crappy GPU. mpv is not intended to be used with bad GPUs. There are
many caveats with drivers or system compositors causing tearing, stutter,
etc. On Windows, you might want to make sure the graphics drivers are
current. In some cases, ancient fallback video output methods can help
(such as
--vo=xvon Linux), but this use is not recommended or supported.
Downloads
For semi-official builds and third-party packages please see mpv.io/installation.
Changelog
There is no complete changelog; however, changes to the player core interface are listed in the interface changelog.
Changes to the C API are documented in the client API changelog.
The release list has a summary of most of the important changes on every release.
Changes to the default key bindings are indicated in restore-old-bindings.conf.
Compilation
Compiling with full features requires development files for several external libraries. Below is a list of some important requirements.
The mpv build system uses waf, but we don't store it in the
repository. The ./bootstrap.py script will download the latest version
of waf that was tested with the build system.
For a list of the available build options use ./waf configure --help. If
you think you have support for some feature installed but configure fails to
detect it, the file build/config.log may contain information about the
reasons for the failure.
NOTE: To avoid cluttering the output with unreadable spam, --help only shows
one of the two switches for each option. If the option is autodetected by
default, the --disable-*** switch is printed; if the option is disabled by
default, the --enable-*** switch is printed. Either way, you can use
--enable-*** or --disable-** regardless of what is printed by --help.
To build the software you can use ./waf build: the result of the compilation
will be located in build/mpv. You can use ./waf install to install mpv
to the prefix after it is compiled.
Example:
./bootstrap.py
./waf configure
./waf
./waf install
Essential dependencies (incomplete list):
- gcc or clang
- X development headers (xlib, xrandr, xext, xscrnsaver, xinerama, libvdpau, libGL, GLX, EGL, xv, ...)
- Audio output development headers (libasound/ALSA, pulseaudio)
- FFmpeg libraries (libavutil libavcodec libavformat libswscale libavfilter and either libswresample or libavresample)
- zlib
- iconv (normally provided by the system libc)
- libass (OSD, OSC, text subtitles)
- Lua (optional, required for the OSC pseudo-GUI and youtube-dl integration)
- libjpeg (optional, used for screenshots only)
- uchardet (optional, for subtitle charset detection)
- vdpau and vaapi libraries for hardware decoding on Linux (optional)
Libass dependencies:
- gcc or clang, yasm on x86 and x86_64
- fribidi, freetype, fontconfig development headers (for libass)
- harfbuzz (optional, required for correct rendering of combining characters, particularly for correct rendering of non-English text on OSX, and Arabic/Indic scripts on any platform)
FFmpeg dependencies:
- gcc or clang, yasm on x86 and x86_64
- OpenSSL or GnuTLS (have to be explicitly enabled when compiling FFmpeg)
- libx264/libmp3lame/libfdk-aac if you want to use encoding (have to be explicitly enabled when compiling FFmpeg)
- Libav also works, but some features will not work. (See section below.)
Most of the above libraries are available in suitable versions on normal Linux distributions. For ease of compiling the latest git master of everything, you may wish to use the separately available build wrapper (mpv-build) which first compiles FFmpeg libraries and libass, and then compiles the player statically linked against those.
If you want to build a Windows binary, you either have to use MSYS2 and MinGW, or cross-compile from Linux with MinGW. See Windows compilation.
FFmpeg vs. Libav
Generally, mpv should work with the latest release as well as the git version of both FFmpeg and Libav. But FFmpeg is preferred, and some mpv features work with FFmpeg only (subtitle formats in particular).
FFmpeg ABI compatibility
mpv does not support linking against FFmpeg versions it was not built with, even if the linked version is supposedly ABI-compatible with the version it was compiled against. Expect malfunctions, crashes, and security issues if you do it anyway.
The reason for not supporting this is because it creates far too much complexity with little to no benefit, coupled with absurd and unusable FFmpeg API artifacts.
Newer mpv versions will refuse to start if runtime and compile time FFmpeg library versions mismatch.
Release cycle
Every other month, an arbitrary git snapshot is made, and is assigned a 0.X.0 version number. No further maintenance is done.
The goal of releases is to make Linux distributions happy. Linux distributions are also expected to apply their own patches in case of bugs and security issues.
Releases other than the latest release are unsupported and unmaintained.
See the release policy document for more information.
Bug reports
Please use the issue tracker provided by GitHub to send us bug reports or feature requests. Follow the template's instructions or the issue will likely be ignored or closed as invalid.
Using the bug tracker as place for simple questions is fine but IRC is recommended (see Contact below).
Contributing
Please read contribute.md.
For small changes you can just send us pull requests through GitHub. For bigger changes come and talk to us on IRC before you start working on them. It will make code review easier for both parties later on.
You can check the wiki or the issue tracker for ideas on what you could contribute with.
Relation to MPlayer and mplayer2
mpv is a fork of MPlayer. Much has changed, and in general, mpv should be considered a completely new program, rather than a MPlayer drop-in replacement.
For details see FAQ entry.
If you are wondering what's different from mplayer2 and MPlayer, an incomplete and largely unmaintained list of changes is located here.
License
GPLv2 "or later" by default, LGPLv2.1 "or later" with --enable-lgpl.
See details.
Contact
Most activity happens on the IRC channel and the github issue tracker.
- GitHub issue tracker: issue tracker (report bugs here)
- User IRC Channel:
#mpvonirc.freenode.net - Developer IRC Channel:
#mpv-develonirc.freenode.net
To contact the mpv team in private write to mpv-team@googlegroups.com. Use
only if discretion is required.