[FFmpeg-devel] [PATCH] avcodec/qtrle: return last frame even if unchanged

[Michael Niedermayer]

On Wed, May 15, 2019 at 10:53:25PM +0200, Hendrik Leppkes wrote:
> On Wed, May 15, 2019 at 8:41 PM Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> >
> > Fixes: Ticket7880
> >
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavcodec/qtrle.c        | 27 +++++++++++++++++++++++++--
> >  tests/ref/fate/qtrle-8bit |  1 +
> >  2 files changed, 26 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavcodec/qtrle.c b/libavcodec/qtrle.c
> > index 2c29547e5a..11226cb842 100644
> > --- a/libavcodec/qtrle.c
> > +++ b/libavcodec/qtrle.c
> > @@ -45,6 +45,7 @@ typedef struct QtrleContext {
> >
> >      GetByteContext g;
> >      uint32_t pal[256];
> > +    int need_flush;
> >  } QtrleContext;
> >
> >  #define CHECK_PIXEL_PTR(n)                                                            \
> > @@ -444,6 +445,12 @@ static av_cold int qtrle_decode_init(AVCodecContext *avctx)
> >      return 0;
> >  }
> >
> > +static void qtrle_flush(AVCodecContext *avctx){
> > +    QtrleContext *s = avctx->priv_data;
> > +
> > +    s->need_flush = 0;
> > +}
> > +
> >  static int qtrle_decode_frame(AVCodecContext *avctx,
> >                                void *data, int *got_frame,
> >                                AVPacket *avpkt)
> > @@ -454,11 +461,26 @@ static int qtrle_decode_frame(AVCodecContext *avctx,
> >      int has_palette = 0;
> >      int ret, size;
> >
> > +    if (!avpkt->data) {
> > +        if (s->need_flush) {
> > +            s->need_flush = 0;
> > +            if ((ret = ff_reget_buffer(avctx, s->frame)) < 0)
> > +                return ret;
> > +            if ((ret = av_frame_ref(data, s->frame)) < 0)
> > +                return ret;
> > +            *got_frame = 1;
> > +        }
> > +        return 0;
> > +    }
> > +
> >      bytestream2_init(&s->g, avpkt->data, avpkt->size);
> >
> >      /* check if this frame is even supposed to change */
> > -    if (avpkt->size < 8)
> > +    if (avpkt->size < 8) {
> > +        s->need_flush = 1;
> >          return avpkt->size;
> > +    }
> > +    s->need_flush = 0;
> >
> >      /* start after the chunk size */
> >      size = bytestream2_get_be32(&s->g) & 0x3FFFFFFF;
> > @@ -572,5 +594,6 @@ AVCodec ff_qtrle_decoder = {
> >      .init           = qtrle_decode_init,
> >      .close          = qtrle_decode_end,
> >      .decode         = qtrle_decode_frame,
> > -    .capabilities   = AV_CODEC_CAP_DR1,
> > +    .flush          = qtrle_flush,
> > +    .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY,
> >  };
> > diff --git a/tests/ref/fate/qtrle-8bit b/tests/ref/fate/qtrle-8bit
> > index 27bb8aad71..39a03b7b6c 100644
> > --- a/tests/ref/fate/qtrle-8bit
> > +++ b/tests/ref/fate/qtrle-8bit
> > @@ -61,3 +61,4 @@
> >  0,        160,        160,        1,   921600, 0xcfd6ad2b
> >  0,        163,        163,        1,   921600, 0x3b372379
> >  0,        165,        165,        1,   921600, 0x36f245f5
> > +0,        166,        166,        1,   921600, 0x36f245f5
> 
> Does this actually work if there is a gap between the last frame and
> the previously changed frame?
> I'm not sure where it would save the proper timestamp.

i had tested it with this:
make -j12 && ./ffmpeg -i test.mov test%d.jpg

and it turned a case with a single frame and 10 skiped ones into 11 frames
so i assume it works. Do you have a case where it does not work ?

thx

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

The greatest way to live with honor in this world is to be what we pretend
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