[Mp4-tech] H264: is access unit delimiter required?

[Gary Sullivan]

I am almost certain that the answer would be that the answer is No.  Part of the motivation behind some key aspects of the design of the video standard was to consider environments like RTP where some packets will be lost and it is therefore beneficial to ensure that slices can be decoded without dependency on a single copy of some picture header information that appears only once at the beginning of each picture in the transmission sequence.  If we assume that decoders include the functionality to decode individual slices when some information has been lost, the access unit delimiter would appear to serve no purpose in such an environment.
Best Regards,
Gary Sullivan
________________________________
From: Victor lyamtsev [mailto:vlyamtsev gmail.com]
Sent: Wednesday, October 24, 2023 7:32 AM
To: mp4-tech lists.mpegif.org
Cc: Gary Sullivan
Subject: Re: [Mp4-tech] H264: is access unit delimiter required?
Does RTP transport require it?
Thank you,
-vl
On 10/23/07, Gary Sullivan <garysull windows.microsoft.com<mailto:garysull windows.microsoft.com>> wrote:
Its presence is not required by the video standard.  However, its presence may be required in some application-level specifications.
Best Regards,
Gary Sullivan
________________________________
From: mp4-tech-bounces lists.mpegif.org<mailto:mp4-tech-bounces lists.mpegif.org> [mailto: mp4-tech-bounces lists.mpegif.org<mailto:mp4-tech-bounces lists.mpegif.org>] On Behalf Of Victor lyamtsev
Sent: Tuesday, October 23, 2023 7:31 AM
To: mp4-tech lists.mpegif.org<mailto:mp4-tech lists.mpegif.org>
Subject: [Mp4-tech] H264: is access unit delimiter required?
Hello,
Regarding parsing of H264 stream...
Do I have to start from searching for Access Unit delimiter to read NAL unit? More to the point: is the Access Unit delimiter required by standard and is it common practice to use it?
Thanks,
-vl
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