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76538ed792
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@6351 b3059339-0415-0410-9bf9-f77b7e298cf2
61 lines
2.7 KiB
Plaintext
61 lines
2.7 KiB
Plaintext
In the RV30 format, another encapsulated data layer for the video stream
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has been introduced. In lack of a name I'll call them sub packets, the
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normal packets which exist in RV10 I'll call - well - packets. The stream
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of bytes which is put in one memory block is named block.
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The format extension has been * by wild guessing and comparing the
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received data between the original viewer and the demuxer.
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Every packet may contain one or more sub packets, and one block may
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be contained inside one or more adjacent (sub) packets.
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A sub packet (fragment) starts with a small header (two letters are one byte):
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aa(bb)[cccc{gggg}dddd{eeee}ff]
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aa: indicates the type of header
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the 2MSB indicate the header type (mask C0)
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C0: the [] part exists, but not () -> whole packet (not fragmented)
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00, 80: the data block is encapsulated inside multiple packets.
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bb contains the sequence number, beginning with 1.
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80 indicates the last sub packet containing data for the
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current block. no C0 or 40 sub packet follows until
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the block has been finished with a 80 sub packet.
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No packet with another stream than the current video stream
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is inside the sub packet chain, at least I haven't seen
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such case - the demuxer will shout in this case.
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40: [] does not exist, the meaning of bb is unknown to me
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data follows to the end of the packet
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mask 3F: unknown
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bb: sub-seq - mask 0x7f: the sequence number of the _fragment_
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mask 0x80: unknown, seems to alternating between 00 and 80
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cccc: mask 3FFF: _total_ length of the packet
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mask C000: unknown, seems to be always 4000
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when it's all 0000, it indicates value >=0x4000, you should read {gggg}
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and use all 16 bits of it. dunno what happens when length>=65536...
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dddd: when it's 0, {} exists (only in this case)
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mask 3FFF: offset of fragment inside the whole packet. it's counted
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from the beginning of the packet, except when hdr&0x80,
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hten it's relative to the _end_ of the packet, so it's
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equal to fragment size!
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mask C000: like cccc, except the first case (always 4000)
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when it's all 0000, it indicates value >=0x4000, you should read {eeee}
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and use all 16 bits of it. dunno what happens when length>=65536...
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ff: sequence number of the assembled (defragmented) packets, beginning with 0
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NOTE: the demuxer should build a table of the subpacket offsets relative to the
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start of whole packet, it's required by the rv20/rv30 video decoders.
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packet header:
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ushort unknown
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ulong blocksize
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ushort streamid
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uchar reserved
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uchar flags 1=reliable, 2=keyframe
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