[Mp4-tech] multi sps and pps, changing resolution on the fly

[Robert J. Landle]

I am also interested in the answer to the multiple PPS and SPS.
I would like to stream to a player like Quicktime or VLC, where my
encoder is free to change image resolution on the fly, i.e. without the
user having to stop and start the decoder/encoder with a new SDP file.
I am thinking of using maybe a list of 5 possible image resolutions.
Is it possible to use an SDP file to configure the decoder with multiple
SPSs and PPSs, each of which correspond to a single resolution in my
list?
If so, can't I just force an IDR frame, begin encoding with the new
resolution,   and change the Id in the slice header to reference the
appropriate SPS/PPS?
The decoder should know to reset itself because it's an IDR frame, and
it should see that the PPSId number in the slice header has changed.
It seems like it's possible.  I haven't tried it myself yet.
Has anyone tried this?
Is there a decoder that supports this, or do I have to write my own?
Thanks,
Bob
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org
[mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Dave Singer
Sent: Wednesday, April 11, 2024 12:54 PM
To: Muhammad imran latif; mp4-tech lists.mpegif.org
Subject: Re: [Mp4-tech] multi sps and pps in MP4 file format
At 5:01  -0700 11/04/07, Muhammad imran latif wrote:
>Hi Guys,
>
>H264 allows multi_sps and Multi_pps in a stream, user
>can point a different sps using selected pps_id. MP4
>file format uses Different video formats and audio
>formats.
>if i want to use
>video = h264
>audio = aac
>to make mp4 file.
>The question :
>will MP4 support the h264 video having multi_sps and
>Multi_pps ?

yes, please look at the AVC Config Record (or separate parameter set
streams)
>which player can play that Mp4 video (multi_SPS and
>PPS) ?

There, I cannot help you.  Sorry.
-- 
David Singer
Apple Computer/QuickTime
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