[FFmpeg-devel] [PATCH, v2 2/4] avc/avcodec: add AV_CODEC_CAP_VARIABLE_DIMENSIONS flag

[Michael Niedermayer]

On Tue, Feb 18, 2020 at 05:42:19PM +0100, Anton Khirnov wrote:
> Quoting Fu, Linjie (2020-02-18 16:06:10)
> > > Is there even a sufficiently strong use case for this? Why not just
> > 
> > Like transcoding reinit-large_420_8-to-small_420_8.h264 (from 352x288 to 240x196)
> > and prefer to keep the resolution changing in the output stream. 
> > 
> > IMHO not modifying the resolution unless it's required by user is kind of natural.
> > 
> > > create a new encoder instance?
> > 
> > Would you please help to elaborate more about "create a new encoder instance?"
> > 
> > What I intended to do is to flush and close the encoder when resolution changing,
> > and reinit/recreate a new one.
> 
> Yes, that's what I mean. Flush and destroy an AVCodecContext and open a
> new one. But then why is there a need for this flag?

some sort of capability check would be needed for flush destroy open too
because there are a range of cases where this would not produce a decodeable
file.
for example some codecs like msmpeg4 do not store the resolution in their 
header and instead its stored in the container only once per stream.

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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