[Ffmpeg-devel] mpeg2 transport stream

[Nico Sabbi]

M?ns Rullg?rd wrote:

>ved kpl said:
>  
>
>>Hi all,
>>
>>In a mpeg2 transport stream, does the random access indicator bit in the
>>adaptation field control always mean that the first byte of the payload is
>>the start of sequence header (0x000001b3).
>>    
>>
>
>I'd have to check the spec to answer that, and I don't have it nearby.
>  
>
"when set to 1 the next pes packet to start in the payload
of transport packets"  <-- notice the plural form
"with the current pid shall contain the first byte of a video sequence 
header
if the pes stream type is 1 or 2 (video) or ..." (same for audio).
"In addition, in these cases a pts shall be present in this or a 
subsequent pes
packet for the first picture following  the sequence header or for the 
audio frame".

so, IIUC, because of the plural form, the RAP flag set doesn't 
necessarily imply the
PUSI set and the alignment of a frame to the payload of the pes packet 
in the same
ts packet as the one with the rap flag set; it just means that the next 
TS packet with PUSI
set begins with a seekable access unit.
If so they could have made better choices :(

>  
>
>>Is the random access indicator
>>always present in all mpeg2 transport streams?
>>    
>>
>
>I've never that bit being set.
>  
>

I've seen it only in DMB