Re: [FFmpeg-devel] [PATCH 1/4] avcodec/rtv1: Check if the minimal size is available in decode_rtv1()

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 1/4] avcodec/rtv1: Check if the minimal size is available in decode_rtv1()
Date: Fri, 22 Sep 2023 23:52:15 +0200
Message-ID: <20230922215215.GA3543730@pb2> (raw)
In-Reply-To: <CAPYw7P7Tm5EDvhpsZ-dv_1i1sKagxzAecVNvPYjerTWrdb4EaA@mail.gmail.com>

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On Fri, Sep 22, 2023 at 11:30:37PM +0200, Paul B Mahol wrote:
> On 9/22/23, Michael Niedermayer <michael@niedermayer.cc> wrote:
> > On Fri, Sep 22, 2023 at 09:32:47PM +0200, Paul B Mahol wrote:
> >> On 9/22/23, Michael Niedermayer <michael@niedermayer.cc> wrote:
> >> > On Thu, Jul 27, 2023 at 01:59:13AM +0200, Michael Niedermayer wrote:
> >> >> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> >> >> ---
> >> >>  libavcodec/rtv1.c | 6 +++++-
> >> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> >> >
> >> > will apply 1-3 of this patchset
> >>
> >> Are you sure this does not break decoding?
> >
> > Well, its a loop over 4x4 blocks, a 16bit "skip" run so the minimum
> > check looks correct.
> > There are 2 end of bitstream checks for early exit but they look like
> > error handling not some normal exit as they leave the frame uninitialized
> >
> 
> FFmpeg default initialization code for AVFrame's buffers does it
> twice, so they are always zeroed or previous values of previous
> buffers in pool.

its rare that correct frame decoding depends on internal AVFrame buffer
ordering

> 
> > Do you have some files so i can double check this is not breaking anything
> 
> Search trac tickets.

thanks, found a zip with 2 video files
ill check it

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

"I am not trying to be anyone's saviour, I'm trying to think about the
 future and not be sad" - Elon Musk

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