204a7725de
This commit generally fixes backward playing in wav, at least in most PCM cases. libavformat's wav demuxer (and actually all other raw PCM based demuxers) have a specific behavior that breaks backward demuxing. The same thing also breaks persistent seek ranges in the demuxer cache, although that's less critical (it just means some cached data gets discarded). The backward demuxing issue is fatal, will log the message "Demuxer not cooperating.", and then typically stop doing anything. Unlike modern media formats, these formats don't organize media data in packets, but just wrap a monolithic byte stream that is described by a header. This is good enough for PCM, which uses fixed frames (a single sample for all audio channels), and for which it would be too expensive to have per frame headers. libavformat (and mpv) is heavily packet based, and using a single packet for each PCM frame causes too much overhead. So they typically "bundle" multiple frames into a single packet. This packet size is obviously arbitrary, and in libavformat's case hardcoded in its source code. The problem is that seeking doesn't respect this arbitrary packet boundary. Seeking is sample accurate. You can essentially seek inside a packet. The resulting packets will not be aligned with previously demuxed packets. This is normally OK. Backward seeking (and some other demuxer layer features) expect that demuxing an earlier demuxed file position eventually results in the same packets, regardless of the seeks that were done to get there. I like to call this "deterministic" demuxing. Backward demuxing in particular requires this to avoid overlaps, which would make it rather hard to get continuous output. Fix this issue by detecting wav and hopefully other raw audio formats with a heuristic (even PCM needs to be detected as heuristic). Then, if a seek is requested, align the seek timestamps on the guessed number of samples in the audio packets returned by the demuxer. The heuristic excludes files with multiple streams. (Except "attachment" video streams, which could be an ID3 tag. Yes, FFmpeg allows ID3 tags on WAV files.) Such files will inherently use the packet concept in some way. We don't know how the demuxer chooses the internal packet size, but we assume that it's fixed and aligned to PCM frame sizes. The frame size is most likely given by block_align (the native wav frame size, according to Microsoft). We possibly need to explicitly read and discard a packet if the seek is done without reading anything before that. We ignore any subsequent packet sizes; we need to avoid the very last packet, which likely has a different size. This hack should be rather benign. In the worst case, it will "round" the seek target a little, but the maximum rounding amount is bounded. Maybe we _could_ round up if SEEK_FORWARD is specified, but I didn't bother. An earlier commit fixed the same issue for mpv's demux_raw. An alternative, and probably much better solution would be clipping decoded data by timestamp. demux.c could allow the type of overlap the wav demuxer introduces, and instruct the decoder to clip the output against the last decoded timestamp. There's already an infrastructure for this (demux_packet.end field) used by EDL/ordered chapters. Although this sounds like a good solution, mpv unfortunately uses floats for timestamps. The rounding errors break sample accuracy. Even if you used integers, you'd need a timebase that is sample accurate (not always easy, since EDL can merge tracks with different sample rates). |
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|---|---|---|
| .github | ||
| audio | ||
| ci | ||
| common | ||
| demux | ||
| DOCS | ||
| etc | ||
| filters | ||
| input | ||
| libmpv | ||
| misc | ||
| options | ||
| osdep | ||
| player | ||
| stream | ||
| sub | ||
| ta | ||
| test | ||
| TOOLS | ||
| video | ||
| waftools | ||
| .gitignore | ||
| .travis.yml | ||
| appveyor.yml | ||
| bootstrap.py | ||
| Copyright | ||
| LICENSE.GPL | ||
| LICENSE.LGPL | ||
| mpv_talloc.h | ||
| README.md | ||
| RELEASE_NOTES | ||
| VERSION | ||
| version.sh | ||
| wscript | ||
| wscript_build.py | ||
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)
- For native DASH playback, FFmpeg needs to be built with --enable-libxml2 (although there are security implications).
- For good nvidia support on Linux, make sure nv-codec-headers is installed and can be found by configure.
- Libav support is broken. (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 FFmpeg. Libav support is currently broken, because they did not add certain FFmpeg API changes which mpv relies on.
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