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

[Dave Singer]

I haven't tried this;  it would be an interesting experiment.
Though changing resolutions on the fly is permitted, it makes for 
interesting integration and user-experience issues.  Should windows, 
once made, resize themselves, or does the user 'own' the window size? 
What do you do if the stream is embedded in say a web page or SMIL 
file, where a specific region size has to be given?  And so on.
At 15:04  -0400 12/04/07, Robert J. Landle wrote:
>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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-- 
David Singer
Apple Computer/QuickTime