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https://github.com/mpv-player/mpv
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change goals slightly..
max_index_distance removed index changed to combination of syncpoint index and pts for keyframes back_ptr changed - points to most correct keyframe, not most recent. max(last_dts) <= syncpoint timestamp <= min(future_pts) git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@17439 b3059339-0415-0410-9bf9-f77b7e298cf2
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ods15
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@ -21,7 +21,7 @@ Extendible
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Compact
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~0.2% overhead, for normal bitrates
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index is <10kb per hour (1 keyframe every 3sec)
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index is <100kb per hour
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a usual header for a file is about 100 bytes (audio + video headers together)
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a packet header is about ~1-5 bytes
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@ -130,7 +130,6 @@ main header:
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version v
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stream_count v
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max_distance v
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max_index_distance v
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tmp_pts=0
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tmp_mul=1
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tmp_stream=0
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@ -224,12 +223,35 @@ frame:
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index:
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index_startcode f(64)
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packet header
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stream_id v
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max_pts v
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index_length v
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for(i=0; i<index_length; i++){
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index_pts v
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index_position v
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syncpoints v
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for(i=0; i<syncpoints; i++){
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syncpoint_pos_div8 v
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}
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for(i=0; i<stream_count; i++){
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for(j=0; j<syncpoint_count; ){
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x v
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type= x & 1
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x>>=1
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if(type){
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flag= x & 1
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x>>=1
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while(x--)
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has_keyframe[j++][i]=flag
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has_keyframe[j++][i]=!flag;
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}else{
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while(x != 1){
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has_keyframe[j++][i]=x&1;
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x>>=1;
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}
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}
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}
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for(j=0; j<syncpoint_count; j++){
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if (!has_keyframe[j++][i]) continue
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A v
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last_pts += A
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keyframe_pts[j][i] = last_pts
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}
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}
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reserved_bytes
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checksum u(32)
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@ -264,7 +286,7 @@ syncpoint:
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coded_pts v
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stream = coded_pts % stream_count
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global_key_pts = coded_pts/stream_count
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back_ptr v
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back_ptr_div8 v
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Complete definition:
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@ -290,9 +312,7 @@ file:
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}
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}
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if (next_code == index_startcode){
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while(!eof){
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index
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}
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index
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index_ptr u(64)
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}
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@ -304,12 +324,12 @@ forward_ptr
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size of the packet data (exactly the distance from the first byte
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after the forward_ptr to the first byte of the next packet)
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back_ptr
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real_back_ptr = back_ptr * 8 + 7
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real_back_ptr must point to a position such that a syncpoint
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startcode begins within the next 8 bytes, and such that at least
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one keyframe for each stream lies between the syncpoint to which
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real_back_ptr points, and the current syncpoint.
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back_ptr_div8
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back_ptr = back_ptr_div8 * 8 + 7
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back_ptr must point to a position within 8 bytes of a syncpoint
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startcode. This syncpoint MUST be the closest syncpoint such that at
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least one keyframe with a pts lower or equal to the original syncpoint's
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global_key_pts for all streams lies between it and the current syncpoint.
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A stream where EOR is set is to be ignored for back_ptr.
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@ -317,6 +337,9 @@ global_key_pts
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After a syncpoint, last_pts of each stream is to be set to:
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last_pts[i] = convert_ts(global_key_pts, timebase[stream], timebase[i])
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global_key_pts MUST be bigger or equal to dts of all past frames across
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all streams, and smaller or equal to pts of all future frames.
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file_id_string
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"nut/multimedia container\0"
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@ -355,13 +378,6 @@ max_distance
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good reason to set it higher, otherwise reasonable error recovery will
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be impossible
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max_index_distance
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max distance of keyframes which are represented in the index, the
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distance between consecutive entries A and B may only be larger if
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there are no keyframes within this stream between A and B
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SHOULD be set to <=32768 or at least <=65536 unless there is a very
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good reason to set it higher
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stream_id
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Stream identifier
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stream_id MUST be < stream_count
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@ -525,23 +541,27 @@ checksum
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forward_ptr until last byte before the checksum).
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max_pts
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The highest pts in the stream.
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s = max_pts % stream_count
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pts = max_pts / stream_count
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The highest pts in the entire file in the timebase of stream 's' .
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index_pts
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value of the pts of a keyframe relative to the last keyframe
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stored in this index
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syncpoint_pos_div8
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offset from begginning of file to up to 7 bytes before the syncpoint
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referred to in this index entry. Relative to position of last
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syncpoint.
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index_position
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position in bytes of the first byte of a keyframe, relative to the
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last keyframe stored in this index
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there MUST be no keyframe with the same stream_id as this index between
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two consecutive index entries if they are more than max_index_distance
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apart
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has_keyframe
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indicates whether this stream has a keyframe between this syncpoint and
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the last syncpoint.
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keyframe_pts
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The pts of the first keyframe for this stream in the region between the
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2 syncpoints, in the stream's timebase.
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index_ptr
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Length in bytes from the first byte of the first index startcode
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to the first byte of the index_ptr. If there is no index, index_ptr
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MUST NOT be written.
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Length in bytes from the first byte of the index startcode to the first
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byte of the index_ptr. If there is no index, index_ptr MUST NOT be
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written.
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id
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the ID of the type/name pair, so it is more compact
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