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

Michael Niedermayer michael at niedermayer.cc
Wed May 8 01:43:08 EEST 2019


On Tue, May 07, 2019 at 02:03:22AM +0200, Marton Balint wrote:
> 
> 
> On Tue, 7 May 2019, Michael Niedermayer wrote:
> 
> >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.
> 
> I guess that can be easily fixed by only copying the buffer if it really is
> a different frame.
> 
> >It also would make encoding the output harder.
> >For example motion estimation would be run over unchanged frames even when
> >no cfr is wanted.
> 
> The performance penalty is much more acceptable to me than the issue
> described in the ticket. Do you see a straightforward way to fix it other
> than reverting?

decoders can in general have frames at the end which need to be flushed
out. For example IPB mpeg1/2/4/...
In the same way the decoder could output a last frame representing the end
exactly

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 
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