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diff --git a/DOCS/OUTDATED-tech/formats.txt b/DOCS/OUTDATED-tech/formats.txt new file mode 100644 index 0000000000..ee4aa8f6ba --- /dev/null +++ b/DOCS/OUTDATED-tech/formats.txt @@ -0,0 +1,160 @@ +1. Input layer, supported devices, methods: + - plain file, with seeking + - STDIN, without seeking backward + - network streaming (currently plain wget-like HTTP and MMS (.asx)) + - VCD (Video CD) track, by direct CDROM device access (not requires mounting disc) + - DVD titles using .IFO structure, by direct DVD device access (not requires mounting disc) + - DVD titles using menu navigation (experimental/alpha, not yet finished!!!) + - CDDA - raw audio from audio CD-ROM discs (using cdparanoia libs) + - RTP streaming (mpeg-ps over multicast only) + - LIVE555 streaming - support SDP/RTSP (using the LIVE555 libs) + - SMB - file access over samba (experimental) + +2. Demuxer/parser layer, supported file/media formats: + + - MPEG streams (ES,PES,PS. no TS support yet) + note: mpeg demuxer silently ignore non-mpeg content, and find mpeg packets + in arbitrary streams. it means you can play directly VCD images (for example + CDRwin's .BIN files) without extracting mpeg files first (with tools like vcdgear) + It accepts all PES variants, including files created by VDR. + Note: VOB (video object) is simple mpeg stream, but it usually has 01BD + packets which may contain subtitles and non-mpeg audio. Usually found on DVD discs. + + Headers: mpeg streams has no global header. each frame sequence (also called GOP, + group of pictures) contains an sequence header, it describes that block. + In normal mpeg 1/2 content there are groups of 12-15 frames (24/30 fps). + It means you can freely seek in mpeg streams, and even can cut it to + small parts with standard file tools (dd, cut) without destroying it. + + Codecs: video is always mpeg video (mpeg1, mpeg2 or mpeg4). + audio is usually mpeg audio (any layer allowed, but it's layer 2 in most files) + but 01BD packets may contain AC3, DTS or LPCM too. + + FPS: mpeg2 content allows variable framerate, in form of delayed frames. + It's mostly used for playback 24fps content at 29.97/30 fps (NTSC) rate. + (so called Telecine or 3:2 pulldown effect) + It means you see 30 frames per second, but there are only 24 different + pictures and some of them are shown longer to fill 30 frame time. + If you encode such files with mencoder, using -ofps 24 or -ofps 23.976 + is recommended. + + - AVI streams. + Two kind of RIFF AVI files exists: + 1. interleaved: audio and video content is interleaved. it's faster and + requires only 1 reading thread, so it's recommended (and mostly used). + 2. non-interleaved: audio and video aren't interleaved, i mean first come + whole video followed by whole audio. it requires 2 reading process or + 1 reading with lots of seeking. very bad for network or cdrom. + 3. badly interleaved streams: mplayer detects interleaving at startup and + enables -ni option if it finds non-interleaved content. but sometimes + the stream seems to be interleaved, but with bad sync so it should be + played as non-interleaved otherwise you get a-v desync or buffer overflow. + + MPlayer supports 2 kind of timing for AVI files: + - bps-based: it is based on bitrate/samplerate of video/audio stream. + this method is used by most players, including avifile and wmp. + files with broken headers, and files created with VBR audio but not + vbr-compliant encoder will result a-v desync with this method. + (mostly at seeking). + - interleaving-based: note: it can't be used togethwer with -ni + it doesn't use bitrate stuff of header, it uses the relative position + of interleaved audio and video chunks. makes some badly encoded file + with vbr audio playable. + + Headers: AVI files has a mandatory header at the begin of the file, + describing video parameters (resolution, fps) and codecs. Optionally + they have an INDEX block at the end of the file. It's optional, but + most files has such block, because it's REQUIRED for seeking. + Btw usually it can be rebuilt from file content, mplayer does it with + the -idx switch. MPlayer can recreate broken index blocks using -forceidx. + As AVI files needs index for random access, broken files with no index + are usually unplayable. + Of course, cutting/joining AVI files needs special programs. + + Codecs: any audio and video codecs allowed, but I note that VBR audio is + not well supported by most players. The file format makes it possible to + use VBR audio, but most players expect CBR audio and fails with VBR, + as VBR is unusual, and Microsoft's AVI specs only describe CBR audio. + I also note, that most AVI encoders/multiplexers create bad files if + using VBR audio. only 2 exception (known by me): NaNDub and MEncoder. + + FPS: only constant framerate allowed, but it's possible to skip frames. + + - ASF streams: + ASF (active streaming format) comes from Microsoft. they developed two + variant of ASF, v1.0 and v2.0. v1.0 is used by their media tools (wmp and + wme) and v2.0 is published and patented :). of course, they differ, + no compatibility at all. (it's just a legality game) + MPlayer supports only v1.0, as nobody ever seen v2.0 files :) + Note, that .ASF files are nowdays come with extension .WMA or .WMV. + UPDATE: MS recently released the ASF v1.0 specs too, but it has some + restrictions making it illegal to read by us :) + + Headers: Stream headers (codecs parameters) can be everywhere (in theory), + but all files i've seen had it at the beginning of the file. + Asf uses fixed packet size, so it is seekable without any INDEX block, + and broken files are playable well. + + Codecs: video is mostly microsoft's mpeg4 variants: MP42, MP43 (aka DivX), + WMV1 and WMV2. but any codecs allowed. + audio is usually wma or voxware, sometimes mp3, but any codecs allowed. + + FPS: no fixed fps, every video frame has an exact timestamp instead. + I've got stream with up to 3 sec frame display times. + + - QuickTime / MOV files: + They come from Mac users, usually with .mov or .qt extension, but as + MPEG Group chose quicktime as recommended file format for MPEG4, + sometimes you meet quicktime files with .mpg or .mp4 extension. + + At first look, it's a mixture of ASF and AVI. + It requires INDEX block for random access and seeking, and even for + playback, like AVI, but uses timestamps instead of constant framerate + and has more flexible stream options (including network stuff) like ASF. + + Headers: header can be placed at the beginning or at the end of file. + About half of my files have it at the beginning, others have it at the end. + Broken files are only playable if they have header at the beginning! + + Codecs: any codecs allowed, both CBR and VBR. + Note: most new mov files use Sorenson video and QDesign Music audio, + they are patented, closed, secret, (TM)-ed etc formats, only Apple's + quicktime player is able to playback these files (on win/mac only). + + - VIVO files: + They are funny streams. They have a human-readable ascii header at + the beginning, followed by interleaved audio and video chunks. + It has no index block, has no fixed packetsize or sync bytes, and most + files even has no keyframes, so forget seeking! + Video is standard h.263 (in vivo/2.0 files it's modified, non-standard + h.263), audio is either standard g.723 or Vivo Siren codec. + + Note, that microsoft licensed vivo stuff, and included in their netshow + v2.0 program, so there are VfW/ACM codecs for vivo video and audio. + + - RealMedia files: + A mixture of AVI and ASF features. It has mandatory headers at the + beginning and an optional INDEX (missing in most files). + The file is constructed of variable size chunks, with small header + telling the stream ID, timestamp, flags (keyframe...) and size. + But it has some features found in ASF files: + The video is actually double-muxed, the video chunks are really + appended fragments of the video frame. RV30+ supports B frames, so + you have to parse some bits of the first fragment to get the real PTS. + The audio frames are fixed size (CBR) but using the same scrambling + (out-of-order interleaving) as in the ASF files. + + Codecs: Audio is either COOK(er), SIPR(o), ATRAC3 or DNET. + The DNET is actually a byte-swapped low-bitrate Dolby AC3 variant :) + Video is RV10 (h263 variant), RV20 (rp G2), RV30 (rp v8) or RV40 (rp v9). + + FPS: variable, just like in ASF. + + Note, that similarity of real and asf has some background - they worked + together on the (never finished/used) ASF v2 spec for some time. + + - GIF files: + The GIF format is a common format for web graphics that supports + animation. These are read through libungif or compatible library. + Variable frame delays are supported, but seeking is not supported. + Seeking will be supported once an index of gif frames can be built. |