[FFmpeg-devel] [PATCH 6/6] avcodec/nuv: Avoid duplicating frames

[Michael Niedermayer]

On Sun, Aug 25, 2019 at 01:05:35PM -0300, James Almer wrote:
> On 8/24/2019 3:18 PM, Michael Niedermayer wrote:
> > Testcase: 14843/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_NUV_fuzzer-5661969614372864
> > Testcase: 16257/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_NUV_fuzzer-5769175464673280
> > 
> > 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/nuv.c          | 25 +++++++++++++++++++++----
> >  tests/ref/fate/nuv-rtjpeg |  1 -
> >  2 files changed, 21 insertions(+), 5 deletions(-)
> > 
> > diff --git a/libavcodec/nuv.c b/libavcodec/nuv.c
> > index 75b14bce5b..39479d2389 100644
> > --- a/libavcodec/nuv.c
> > +++ b/libavcodec/nuv.c
> > @@ -42,6 +42,7 @@ typedef struct NuvContext {
> >      unsigned char *decomp_buf;
> >      uint32_t lq[64], cq[64];
> >      RTJpegContext rtj;
> > +    AVPacket flush_pkt;
> >  } NuvContext;
> >  
> >  static const uint8_t fallback_lquant[] = {
> > @@ -172,6 +173,20 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> >          NUV_COPY_LAST     = 'L'
> >      } comptype;
> >  
> > +    if (!avpkt->data) {
> > +        if (avctx->internal->need_flush) {
> > +            avctx->internal->need_flush = 0;
> > +            ret = ff_setup_buffered_frame_for_return(avctx, data, c->pic, &c->flush_pkt);
> > +            if (ret < 0)
> > +                return ret;
> > +            *got_frame = 1;
> > +        }
> > +        return 0;
> > +    }
> > +    c->flush_pkt = *avpkt;
> > +    c->pic->pkt_dts = c->flush_pkt.dts;
> > +
> > +
> >      if (buf_size < 12) {
> >          av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
> >          return AVERROR_INVALIDDATA;
> > @@ -204,8 +219,8 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> >          }
> >          break;
> >      case NUV_COPY_LAST:
> > -        keyframe = 0;
> > -        break;
> > +        avctx->internal->need_flush = 1;
> > +        return buf_size;
> >      default:
> >          keyframe = 1;
> >          break;
> > @@ -313,6 +328,7 @@ retry:
> >      if ((result = av_frame_ref(picture, c->pic)) < 0)
> >          return result;
> >  
> > +    avctx->internal->need_flush = 0;
> >      *got_frame = 1;
> >      return orig_size;
> >  }
> > @@ -364,6 +380,7 @@ AVCodec ff_nuv_decoder = {
> >      .init           = decode_init,
> >      .close          = decode_end,
> >      .decode         = decode_frame,
> > -    .capabilities   = AV_CODEC_CAP_DR1,
> > -    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
> > +    .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY,
> > +    .caps_internal  = FF_CODEC_CAP_SETS_PKT_DTS | FF_CODEC_CAP_SETS_PKT_POS |
> > +                      FF_CODEC_CAP_INIT_CLEANUP,
> >  };
> > diff --git a/tests/ref/fate/nuv-rtjpeg b/tests/ref/fate/nuv-rtjpeg
> > index b6f3b080dc..0914b985ec 100644
> > --- a/tests/ref/fate/nuv-rtjpeg
> > +++ b/tests/ref/fate/nuv-rtjpeg
> > @@ -6,7 +6,6 @@
> >  0,        118,        118,        0,   460800, 0x54aedafe
> >  0,        152,        152,        0,   460800, 0xb7aa8b56
> >  0,        177,        177,        0,   460800, 0x283ea3b5
> > -0,        202,        202,        0,   460800, 0x283ea3b5
> 
> I haven't been following these cfr -> vfr patches too closely, but why
> remove the duplicate frames (thus changing the expected compliant
> behavior) instead of ensuring the duplicate ones are made with no
> performance penalty by reusing the buffer reference from the previous frame?

Because a filter or encoder or whatever follows the decoder would then process
them multiple times unneccessarily.

thx

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

Observe your enemies, for they first find out your faults. -- Antisthenes
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