diff options
| -rw-r--r-- | DOCS/tech/mpcf.txt | 71 |
1 files changed, 35 insertions, 36 deletions
diff --git a/DOCS/tech/mpcf.txt b/DOCS/tech/mpcf.txt index b53b36bb7a..2ab24d1bd0 100644 --- a/DOCS/tech/mpcf.txt +++ b/DOCS/tech/mpcf.txt @@ -121,7 +121,6 @@ stream_header: time_base_denom v msb_timestamp_shift v initial_timestamp_predictor v(3) - initial_data_size_predictor v(2) fixed_fps u(1) index_flag u(1) reserved u(6) @@ -157,14 +156,10 @@ frame if(stream_id_plus1[frame_code]==0){ stream_id v } - if(flags[frame_code]&4){ - if(flags[frame_code]&1){ - timestamp v - }else{ - lsb_timestamp v - } + if((flags[frame_code]&3)==3){ + coded_timestamp v } - if(flags[frame_code]&8){ + if(flags[frame_code]&4){ data_size_msb v } data @@ -295,7 +290,7 @@ time_base_nom / time_base_denom = time_base timestamps need fewer bits msb_timestamp_shift - amount of bits msb_timestamp is shifted left before adding lsb_timestamp + amount of bits in lsb_timestamp MUST be <16 fixed_fps @@ -325,26 +320,29 @@ frame_code different from the first byte of any startcode flags[frame_code] - the bits of the flags from MSB to LSB are KDTTT - TTT is the timestamp_code, 000,001,010 use the last timestamp + the - first, second and third last unique timestamp difference, so if - the timestamp differences, are +3,+1,+2,+2,+1 then last diff is - +1, second is +2 and third is +3 - 100,101 mean that the lsb or full timestamp is coded - if TTT is 100, then the timestamp is calculated by - mask = (1<<msb_timestamp_shift)-1; - delta= last_timestamp - mask/2 - timestamp= ((timestamp_lsb-delta)&mask) + delta - TTT must be 101 if the packet_type is not 0 - the last timestamp differences are reset to the + the bits of the flags from MSB to LSB are KDTT + TT is the timestamp_code + 00,01,10 predicted delta timestamps + 11 timestamp coded, either lsb or full timestamp + + predicted delta timestamp use the last timestamp from the + current stream + the first, second and third last unique + timestamp difference, so if the timestamp differences, where + +3,+1,+2,+2,+1 then last difference is +1, second is +2 and + third is +3 + predicted delta timestamps MUST NOT be used in type > 0 frames + or in type 0 frames if there was no full timestamp in the + current stream after the last type > 0 frame + + the least recent used delta timestamps are reset to the initial_timestamp_predictor values from the stream header if a packet of type not 0 in encountered - if D is 1 then data_size_msb is coded, otherwise its 0 + if D is 1 then data_size_msb is coded, otherwise data_size_msb is 0 K is the keyframe_type 0-> no keyframe, 1-> keyframe, - flags=7 can be used to mark illegal frame_code bytes - frame_code=78 must have flags=7 + flags=16 can be used to mark illegal frame_code bytes + frame_code=78 must have flags=16 frame_type if the first byte of a frame is 'N' then the frame_type is 2 otherwise @@ -369,18 +367,19 @@ data_size_lsb[frame_code] must be <250 data_size - if(data_size_lsb == data_size_mul) - data_size= last; - else if(data_size_lsb == data_size_mul+1) - data_size= next_last; - else if(data_size_lsb < data_size_mul) - data_size= data_size_lsb + data_size_msb*data_size_mul; - else reserved - next_last is the second last unique data_size, for example: - previous data_size: 123,500,312,500,500 last=500, next_last=312 - last and next_last are reset to the initial_data_size_predictor values - stored in the stream header if an frame with type > 0 is encountered - + data_size= data_size_lsb + data_size_msb*data_size_mul; + +coded_timestamp + if coded_timestamp < (1<<msb_timestamp_shift) then its a + lsb timestamp, otherwise its a full timestamp + (1<<msb_timestamp_shift) + lsb timestamps are converted to full timesamps by: + mask = (1<<msb_timestamp_shift)-1; + delta= last_timestamp - mask/2 + timestamp= ((timestamp_lsb-delta)&mask) + delta + a full timestamp must be used if the packet_type is not 0 or there is no + reference timestamp available after the last not 0 frame with the + current stream_id + lsb_timestamp least significant bits of the timestamp in time_base precission Example: IBBP display order |