[MPlayer-dev-eng] mpeg4-es format

[Michael Niedermayer]

Hi

On Thursday 23 January 2003 02:00, Arpi wrote:
> Hi,
>
> Michael said that mpeg4-es is similar to mpeg 1/2 es, there are picture
> header, slices etc ...
>
> just tried startcode search on 2 of the mpeg4-es samples on mphq:
>
> 00000000 1B0
> 00000005 1B5
> 0000000A 101
> 0000000E 120
> 0000001C 1B6
> 00001162 1B6
> 0000136B 1B6
> 00001405 1B6
> 000014A7 1B6
> 0000156E 1B6
> 00001622 1B6
> 000017B2 1B6
> 00001808 1B6
> 00001867 1B6
> 000018E9 1B6
> ..
>
> and
>
> 00000000 100
> 00000004 120
> 00000018 1B6
> 00002AFC 1B6
> 000034E2 1B6
> 00003849 1B6
> 00003C04 1B6
> 00004CD9 1B6
> 000050C4 1B6
> 00005467 1B6
> ..
>
> so it seems the first frame is prefixed by some headers, and then there is
> only one chunk with startcode 1B6 for each frame? is it always true?
yes ... (there are some useless/advanced things like fgs or 2d/3d mesh or such 
stuff which use different startcodes IIRC)
btw slices use shorter (and variable) length "startcodes" so they dont appear 
in the list 

>
> what do those header startcodes mean?
> it seems only 120 is common, maybe it contains width/height/fps ?
yes, but the fps field is optional, as mpeg4 has variable fps

[...]

Michael