mirror of https://github.com/mpv-player/mpv
211 lines
8.4 KiB
Plaintext
211 lines
8.4 KiB
Plaintext
Understanding MPlayer's etc/codecs.conf File
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Introduction
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------------
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MPlayer features a very flexible codec architecture which allows it to
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use its own open source codecs, as well as open source libraries, Win32
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codec DLLs and other binary codec modules. To the MPlayer user, the
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most visible piece of this architecture is the etc/codecs.conf file. This
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is a text-based configuration file that controls which MPlayer components
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are in charge of handling particular compressed data formats.
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The codecs.conf file is stored either in a shared directory for all system
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users to access, or in the .mplayer directory in a user's home
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directory. When MPlayer starts, it first looks for a codecs.conf file in a
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user's home directory. Failing that, it searches for the shared file. If
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no codecs.conf file is found MPlayer falls back on its internal hardcoded
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configuration. If the file is present but has syntax errors, MPlayer will
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report the error.
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The codecs.conf file is really quite simple. It is simply a collection of
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codec definition blocks that define how different media types should be
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handled. There are a number of keywords that can occur in a block. Not all
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of them are required and no particular order is enforced.
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Editing codecs.conf
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-------------------
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You can edit codecs.conf using your favorite text editor. Anything that
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comes after a semicolon (;) on a line is regarded as a comment. For
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example:
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; this is a comment
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format 0x34616d69 ; "ima4" (MOV files)
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The codec blocks can be in any order; the file parser doesn't
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care. However, they are organized in a particular order for the benefit of
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human readers. For example, all of the open source decoders that MPlayer
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implements natively are grouped in one section.
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Release Number
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--------------
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Your codecs.conf now requires a release number to avoid codec release
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incompatibilities. The format is simple: (YYYYMMDD)
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release 20020520
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Whenever changes are made to the codecs that *require* an updated
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codecs.conf, then MPlayer will no longer accept outdated versions.
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It is not recommended to change this line unless you know exactly
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what you are doing.
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Video Codecs
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------------
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Let's jump right in with an example. Here is an example video codec block:
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videocodec indeo5ds
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info "Intel Indeo 5"
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status working
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fourcc IV50,iv50
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driver dshow
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dll "ir50_32.dll"
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guid 0x30355649, 0x0000, 0x0010, 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71
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out YV12
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out YUY2
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out BGR32,BGR24,BGR16,BGR15
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This is a particularly full-featured video codec. The "videocodec" keyword
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identifies the fact that this is the start of a new video
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codec. "indeo5ds" is MPlayer's unique name for the codec. You have to use
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this name with the -vc/-ac option.
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The next line has the keyword "info" which specifies a human-readable
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comment accompanying this codec. This is printed by -vc help / -ac help.
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The "status" keyword carries information about the codec's functional
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status. MPlayer currently recognizes 4 status levels: working, buggy,
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crashing, and untested. When it gets to codec auto-selection, it tries
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untested first (to force users to test it for us and report results :)),
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then working and finally buggy ones. Codecs marked crashing won't be tried,
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unless explicitly (-vc/-ac) selected.
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The next line lists 4-character codes (FOURCCs) that are associated with
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this codec. There can be more than one FOURCC specified on a fourcc line
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as long as they are separated with a comma. There can also be multiple
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fourcc lines in the codec. A second fourcc can also be given, separated
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with a space. MPlayer will replace the original fourcc in the headers with
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this one before opening the codec. It's useful for win32 codecs checking for
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the fourccs.
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The "driver" keyword associates this codec with an internal MPlayer
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decoder module. MPlayer has a module named "dshow" that handles data
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encoded by the codec. See -vfm help / -afm help for the available module list.
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The "dll" keyword specifies which Win32/XAnim/Real/Quicktime binary
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module needs to be loaded. It's also used to specify which FFmpeg codec
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to load. The list of FFmpeg codecs can be found in libavcodec/allcodecs.c.
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The "guid" keyword identifies a 16-byte Microsoft GUID that some media
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files use to identify codecs. Used only for win32 dshow and DMO codecs.
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The "out" keyword identifies which output format the decoder is known
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to provide. Just like the fourcc line, there can be multiple out lines or
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multiple comma-separated output formats on the same line. The output
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formats should be listed in order of preference.
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The outfmt values can be followed by one or more flags, like flip, noflip,
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static, query. The flags are defined as follows:
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"flip":
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If this flag is set for a given format, then o_bih->biHeight will NOT be
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set to -bih->biHeight, i.e. the image will be decoded upside-down.
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Used only by vfw and vfwex codecs.
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"noflip":
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This flag is ignored (no effect) without "flip" being set!
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If this flag is set, it means the codec doesn't decode upside-down,
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although it's told to do so.
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"yuvhack":
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This flag is required for the old win32 ms-mpeg4 vfw codecs, including
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MP42 and DIV3 (DivX 3.11). These DLLs actually support YUV formats,
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but the query/begin functions are buggy and don't accept YUV fourccs
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(the decode function accepts it and works well!)
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If this flag is set, then o_bih->biCompression will be set to 0 for
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the initialization for the YUV modes. Used only by vfw/vfwex codecs.
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"query":
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This flag is used to control VDCTRL_QUERY_FORMAT for vfw/vfewx codecs.
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If this flag is set, the control() will query the codec for the csp
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support, otherwise it will assume a constant csp table. Required for
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some DLLs (like huffyuv, CRAM).
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"static",
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This flag forces STATIC (instead of TEMP) buffer allocation for the codec.
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Used for some very old DLLs like Indeo 3 and for some XAnim codecs like
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cinepak. See dr-methods.txt for details on buffer types.
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The "in" keyword -- UNDOCUMENTED
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Audio Codecs
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------------
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Here is an example of a rather full-featured audio codec block:
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audiocodec mp3
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info "MPEG layer-2, layer-3"
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status working
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comment "Optimized to MMX/SSE/3Dnow!"
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format 0x50
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format 0x55
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format 0x33706d2e ; ".mp3" CBR/VBR MP3 (MOV files)
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format 0x5500736d ; "ms\0\x55" older mp3 fcc (MOV files)
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driver mp3lib
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dll "mp3lib (mpglib)"
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flags seekable
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Many of the keywords are the same as a video codec block. However, we see
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a few that we haven't seen before. The "comment" keyword identifies
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another human-readable note for this codec.
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The "format" keyword performs a similar job as the fourcc line. However,
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since certain media file formats (notably AVI) identify audio formats with
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16-bit numbers rather than 32-bit FOURCCs, it's necessary to use this
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convention to accommodate them. However, as shown in this example, FOURCCs
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can also be specified with the format keyword as long as they're converted
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to their hex representation. It's important to note that this can be
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useful for video codecs as well if a FOURCC contains a space (such as
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Apple's "rle " codec).
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The "flags" keywords identifies any additional abilities of this
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codec. Currently, seekable is the only supported flag.
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Adding FFmpeg Codecs
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-------------------
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example codec:
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videocodec ffmdec
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info "FFmpeg Sony PlayStation MDEC (Motion DECoder)"
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status working
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fourcc MDEC ; internal MPlayer FourCC
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driver ffmpeg
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dll mdec
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out YV12
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The "videocodec" name should start with ff to differentiate it from other
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libraries or binary codecs.
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The "dll" name comes from the codec source file or the libavcodec/allcodecs.c
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file.
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The "out" colorspace can be found in the codec source file in the PIX_FMT
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struct. Note that some codecs may have several pix_fmt structs.
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The pix_fmt can be converted to the codecs.conf "out" format by reading
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the fmt_conversion.c file.
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libmpdemux/mp_taglists.c
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--------------
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Sometimes the lavf demuxer will not pass on a fourcc (mostly video game
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formats or other containers that do not support isom/riff tags). You will have
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to make one based on the codec_id listed in the codec source file.
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Note that it is a good idea to mark any fourcc you create as
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' ; internal MPlayer FourCC'. In case another codec uses that fourcc,
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you can easily change the internal one. Also this will stop other projects
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from thinking of the internal tag as a real fourcc found in the wild.
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libmpdemux/demuxer.c
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--------------
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Some audio codecs require a parser, you can see which ones do
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by reading the parsers section in libavcodec/allcodecs.c.
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EOF
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