[FFmpeg-devel] [PATCH] avcodec/qpeg: Optimize long runs in qpeg_decode_intra() not spanning a full row

[Paul B Mahol]

On 1/7/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> On Mon, Jan 07, 2019 at 08:51:33PM +0100, Paul B Mahol wrote:
>> On 1/7/19, https://ieeexplore.ieee.org/document/7291728Michael
>> Niedermayer <michael at niedermayer.cc> wrote:
>> > On Mon, Jan 07, 2019 at 07:41:04PM +0100, Paul B Mahol wrote:
>> >> On 1/7/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
>> >> > Fixes: Timeout
>> >> > Fixes:
>> >> > 11354/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_QPEG_fuzzer-5766275943366656
>> >> >
>> >> > Before: Executed
>> >> > clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_QPEG_fuzzer-5766275943366656
>> >> > in 9470 ms
>> >> > After : Executed
>> >> > clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_QPEG_fuzzer-5766275943366656
>> >> > in  134 ms
>> >> >
>> >> > Found-by: continuous fuzzing process
>> >> > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
>> >> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>> >> > ---
>> >> >  libavcodec/qpeg.c | 5 ++++-
>> >> >  1 file changed, 4 insertions(+), 1 deletion(-)
>> >> >
>> >> > diff --git a/libavcodec/qpeg.c b/libavcodec/qpeg.c
>> >> > index cb452621e7..654fd998d6 100644
>> >> > --- a/libavcodec/qpeg.c
>> >> > +++ b/libavcodec/qpeg.c
>> >> > @@ -80,7 +80,10 @@ static void qpeg_decode_intra(QpegContext *qctx,
>> >> > uint8_t
>> >> > *dst,
>> >> >
>> >> >              p = bytestream2_get_byte(&qctx->buffer);
>> >> >              for(i = 0; i < run; i++) {
>> >> > -                dst[filled++] = p;
>> >> > +                int step = FFMIN(run - i, width - filled);
>> >> > +                memset(dst+filled, p, step);
>> >> > +                filled += step;
>> >> > +                i      += step - 1;
>> >> >                  if (filled >= width) {
>> >> >                      filled = 0;
>> >> >                      dst -= stride;
>> >> > --
>> >> > 2.20.1
>> >> >
>> >> > _______________________________________________
>> >> > ffmpeg-devel mailing list
>> >> > ffmpeg-devel at ffmpeg.org
>> >> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >> >
>> >>
>> >> lgtm if output does not change.
>> >
>> > fate-qpeg passes and it executes this codepath
>> > do you have any other files i should test ?
>> >
>>
>> look in samples.ffmpeg.org ?
>
> ive found and tested
> qpeg-test.avi
> Space.avi
> Clock.avi
>
> anything else i should test ?

Every single possible encoder output.
On serious side its fine.

>
> thanks
>
> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> The educated differ from the uneducated as much as the living from the
> dead. -- Aristotle
>