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author | arpi <arpi@b3059339-0415-0410-9bf9-f77b7e298cf2> | 2002-04-13 02:09:18 +0000 |
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committer | arpi <arpi@b3059339-0415-0410-9bf9-f77b7e298cf2> | 2002-04-13 02:09:18 +0000 |
commit | ae80a63c97121a6f2694bd64a08455bd59341a11 (patch) | |
tree | 60324b0070732424d0b477344c5bc0038ec4ae1b /DOCS/tech/general.txt | |
parent | 3962480f56fd954ecfe2bf806628c25395d0726e (diff) | |
download | mpv-ae80a63c97121a6f2694bd64a08455bd59341a11.tar.bz2 mpv-ae80a63c97121a6f2694bd64a08455bd59341a11.tar.xz |
updated
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@5587 b3059339-0415-0410-9bf9-f77b7e298cf2
Diffstat (limited to 'DOCS/tech/general.txt')
-rw-r--r-- | DOCS/tech/general.txt | 150 |
1 files changed, 48 insertions, 102 deletions
diff --git a/DOCS/tech/general.txt b/DOCS/tech/general.txt index 146c03cbdc..e9ab6ee48d 100644 --- a/DOCS/tech/general.txt +++ b/DOCS/tech/general.txt @@ -2,13 +2,18 @@ So, I'll describe how this stuff works. The main modules: -1. streamer.c: this is the input layer, this reads the file or the VCD or - stdin. what it has to know: appropriate buffering by sector, seek, skip - functions, reading by bytes, or blocks with any size. The stream_t - structure describes the input stream, file/device. - -2. demuxer.c: this does the demultiplexing of the input to audio and video - channels, and their reading by buffered packages. +1. stream.c: this is the input layer, this reads the input media (file, stdin, + vcd, dvd, network etc). what it has to know: appropriate buffering by + sector, seek, skip functions, reading by bytes, or blocks with any size. + The stream_t (stream.h) structure describes the input stream, file/device. + + There is a stream cache layer (cache2.c), it's a wrapper for the stream + API. It does fork(), then emulates stream driver in the parent process, + and stream user in the child process, while proxying between them using + preallocated big memory chunk for FIFO buffer. + +2. demuxer.c: this does the demultiplexing (separating) of the input to + audio, video or dvdsub channels, and their reading by buffered packages. The demuxer.c is basically a framework, which is the same for all the input formats, and there are parsers for each of them (mpeg-es, mpeg-ps, avi, avi-ni, asf), these are in the demux_*.c files. @@ -16,11 +21,11 @@ The main modules: 2.a. demux_packet_t, that is DP. Contains one chunk (avi) or packet (asf,mpg). They are stored in memory as - in chained list, cause of their different size. + in linked list, cause of their different size. 2.b. demuxer stream, that is DS. Struct: demux_stream_t - Every channel (a/v) has one. This contains the packets for the stream + Every channel (a/v/s) has one. This contains the packets for the stream (see 2.a). For now, there can be 3 for each demuxer : - audio (d_audio) - video (d_video) @@ -68,7 +73,24 @@ The main modules: DEMUXER: Too many (%d in %d bytes) audio packets in the buffer error shows up. -So everything is ok 'till now, I want to move them to a separate lib. +2.d. video.c: this file/function handle the reading and assembling of the + video frames. each call to video_read_frame() should read and return a + single video frame, and it's duration in seconds (float). + The implementation is splitted to 2 big parts - reading from mpeg-like + streams and reading from one-frame-per-chunk files (avi, asf, mov). + Then it calculates duration, either from fixed FPS value, or from the + PTS difference between and after reading the frame. + +2.e. other utility functions: there are some usefull code there, like + AVI muxer, or mp3 header parser, but leave them for now. + +So everything is ok 'till now. It can be found in libmpdemux/ library. +It should compile outside of mplayer tree, you just have to implement few +simple functions, like mp_msg() to print messages, etc. +See libmpdemux/test.c for example. + +See also formats.txt, for description of common media file formats and their +implementation details in libmpdemux. Now, go on: @@ -86,7 +108,7 @@ Now, go on: sleep (wait until a_frame>=v_frame) display the frame apply A-V PTS correction to a_frame - check for keys -> pause,seek,... + handle events (keys,lirc etc) -> pause,seek,... } When playing (a/v), it increases the variables by the duration of the @@ -173,101 +195,25 @@ Now, go on: Also, doesn't/badly works with some drivers. Only used if none of the above works. -4. Codecs. They are separate libs. - For example libac3, libmpeg2, xa/*, alaw.c, opendivx/*, loader, mp3lib. +4. Codecs. Consists of libmpcodecs/* and separate files or libs, + for example liba52, libmpeg2, xa/*, alaw.c, opendivx/*, loader, mp3lib. - mplayer.c doesn't call the directly, but through the dec_audio.c and + mplayer.c doesn't call them directly, but through the dec_audio.c and dec_video.c files, so the mplayer.c doesn't have to know anything about - the codec. + the codecs. + + libmpcodecs contains wrapper for every codecs, some of them include the + codec function implementation, some calls functions from other files + included with mplayer, some calls optional external libraries. + file naming convention in libmpcodecs: + ad_*.c - audio decoder (called through dec_audio.c) + vd_*.c - video decoder (called through dec_video.c) + ve_*.c - video encoder (used by mencoder) + vf_*.c - video filter (see option -vop) 5. libvo: this displays the frame. - The constants for different pixelformats are defined in img_format.h, - their usage is mandatory. - - Each vo driver _has_ to implement these: - - IMPORTANT: it's mandatorial that every vo driver support the YV12 format, - and one (or both) of BGR15 and BGR24, with conversion, if needed. - If these aren't supported, not every codec will work! The mpeg codecs - can output only YV12, and the older win32 DLLs only 15 and 24bpp. - There is a fast MMX-optimized 15->16bpp converter, so it's not a - significant speed-decrease! - - The BPP table, if the driver can't change bpp: - current bpp has to accept these - 15 15 - 16 15,16 - 24 24 - 24,32 24,32 - - If it can change bpp (for example DGA 2, fbdev, svgalib), then if possible - we have to change to the desired bpp. If the hardware doesn't support, - we have to change to the one closest to it, and do conversion! - - preinit(): - init the video system (to support querying for supported formats) - THIS IS CALLED ONLY ONCE - - control(): - Current controls: - VOCTRL_QUERY_FORMAT - queries if a given pixelformat is supported. - return value: flags: - 0x1 - supported - 0x2 - supported without conversion (define 0x1 too!) - 0x4 - sub/osd supported (has draw_alpha) - 0x8 - hardware handles subpics - 0x100 - driver/hardware handles timing (blocking) - VOCTRL_GET_IMAGE - libmpcodecs Direct Rendering interface - You need to set mpi (mp_image.h) structure, for example, - look at vo_x11, vo_sdl, vo_xv or mga_common. - VOCTRL_RESET - reset the video device - This is sent on seeking and similar and is useful if you are - using a device which prebuffers frames that need to flush them - before refilling audio/video buffers. - VOCTRL_PAUSE - VOCTRL_RESUME - VOCTRL_GUISUPPORT - return true only if driver supports co-operation with - MPlayer's GUI (not yet used by GUI) - VOCTRL_QUERY_VAA - this is used by the vidix extension - this is used by the vidix extension to fill a vo_vaa_t struct, - I do not know how this works since I'm not the author of this - - config(): - Set up the video system. You get the dimensions and flags. - Flags: - 0x01 - fullscreen (-fs) - 0x02 - mode switching (-vm) - 0x04 - software scaling (-zoom) - 0x08 - flipping (-flip) -- REQUIRED to support this - Also these flags you can get from vo_flags too and they're - defined as VOFLAG_* (see libvo/video_out.h) - - uninit(): - Uninit the whole system, this is on the same "level" as preinit. - - draw_slice(): this displays YV12 pictures (3 planes, one full sized that - contains brightness (Y), and 2 quarter-sized which the colour-info - (U,V). MPEG codecs (libmpeg2, opendivx) use this. This doesn't have - to display the whole frame, only update small parts of it. - - draw_frame(): this is the older interface, this displays only complete - frames, and can do only packed format (YUY2, RGB/BGR). - Win32 codecs use this (DivX, Indeo, etc). - - draw_alpha(): this displays subtitles and OSD. - It's a bit tricky to use it, since it's not a part of libvo API, - but a callback-style stuff. The flip_page() has to call - vo_draw_text(), so that it passes the size of the screen and the - corresponding draw_alpha() implementation for the pixelformat - (function pointer). The vo_draw_text() checks the characters to draw, - and calls draw_alpha() for each. - As a help, osd.c contains draw_alpha for each pixelformats, use this - if possible! - - flip_page(): this is called after each frame, this diplays the buffer for - real. This is 'swapbuffers' when double-buffering. + + for details on this, read libvo.txt 6. libao2: this control audio playing |