[FFmpeg-devel] [PATCH 2/4] avcodec/qtrle: return last frame even if unchanged

[Michael Niedermayer]

On Fri, May 31, 2019 at 10:28:15PM +0200, Marton Balint wrote:
> 
> 
> On Thu, 30 May 2019, Michael Niedermayer wrote:
> 
> >Fixes: Ticket7880
> >
> >Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> >---
> >libavcodec/qtrle.c        | 42 +++++++++++++++++++++++++++++++++++----
> >tests/ref/fate/qtrle-8bit |  1 +
> >2 files changed, 39 insertions(+), 4 deletions(-)
> >
> >diff --git a/libavcodec/qtrle.c b/libavcodec/qtrle.c
> >index 2c29547e5a..4add1aded6 100644
> >--- a/libavcodec/qtrle.c
> >+++ b/libavcodec/qtrle.c
> >@@ -45,6 +45,8 @@ typedef struct QtrleContext {
> >
> >    GetByteContext g;
> >    uint32_t pal[256];
> >+    int need_flush;
> >+    AVPacket flush_pkt;
> >} QtrleContext;
> >
> >#define CHECK_PIXEL_PTR(n)                                                            \
> >@@ -444,6 +446,12 @@ 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 +462,32 @@ 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;
> >+            s->frame->pkt_pos      = s->flush_pkt.pos;
> >+            s->frame->pkt_duration = s->flush_pkt.duration;
> >+            s->frame->pkt_dts      = s->flush_pkt.dts;
> >+            s->frame->pkt_pts      =
> >+            s->frame->pts          = s->flush_pkt.pts;
> 
> This does not seem to work, because the magic in decode_simple_internal in
> decode.c will overwrite these fields. Alternative approach which seems to
> work is assigning the AVPacket fields instead:
> 
>             avpkt->pos      = s->flush_pkt.pos;
>             avpkt->duration = s->flush_pkt.duration;
>             avpkt->dts      = s->flush_pkt.dts;
>             avpkt->pts      = s->flush_pkt.pts;
> 
> Looks a bit ugly, but as far as I see we are using an internal packet, and
> not the one provided by the user, so it might be OK.

ill repost this with a different, less ugly variant. 

Please recheck if that works!

[...]
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