[FFmpeg-devel] [PATCH 1/2] Revert "avcodec/qtrle: Do not output duplicated frames on insufficient input"

[Michael Niedermayer]

On Sun, May 05, 2019 at 08:51:08PM +0200, Marton Balint wrote:
> This reverts commit a9dacdeea6168787a142209bd19fdd74aefc9dd6.
> 
> I don't think it is a good idea to drop frames from CFR input just because they
> are duplicated, that can cause issues for API users expecting CFR input. Also
> it can cause issues at the end of file, if the last frame is a duplicated
> frame.
> 
> Fixes ticket #7880.
> 
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
>  libavcodec/qtrle.c        |  12 ++---
>  tests/ref/fate/qtrle-8bit | 109 ++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 115 insertions(+), 6 deletions(-)

This change would make the decoder quite a bit slower. It also would make 
encoding the output harder.
For example motion estimation would be run over unchanged frames even when
no cfr is wanted.

Also if one for consistency wants every decoder to not drop duplicated things
that will cause some major problems in other decoders.
Iam thinking of MPEG2 here, where the duplication is at a field level
perfectly progressive material would be turned into some mess with field
repetition in that case. Again undoing that in a subsequent stage would be
quite a bit harder and wastefull

so my oppinion is that its better to produce duplicated things only when
needed and not always and hardcoded in the decoder.

Thanks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

It is what and why we do it that matters, not just one of them.
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