Ticket #8343: 11_fix_h261dec_keyframe.patch

libavcodec/h261.h

@@ -35 +35 @@
  * H261Context
  */
 typedef struct H261Context {
     MpegEncContext s;
 
+    int freeze_picture_release; // 1 if freeze picture release bit is set in the picture header
     int current_mba;
     int mba_diff;
     int mtype;
     int current_mv_x;
     int current_mv_y;

libavcodec/h261dec.c

@@ -500 +500 @@
     s->picture_number = (s->picture_number & ~31) + i;
 
     s->avctx->framerate = (AVRational) { 30000, 1001 };
 
     /* PTYPE starts here */
-    skip_bits1(&s->gb); /* split screen off */
-    skip_bits1(&s->gb); /* camera  off */
-    skip_bits1(&s->gb); /* freeze picture release off */
+    skip_bits1(&s->gb); /* split screen indicator */
+    skip_bits1(&s->gb); /* document camera indicator */
+    h->freeze_picture_release = get_bits1(&s->gb); /* freeze picture release */
 
     format = get_bits1(&s->gb);
 
     // only 2 formats possible
     if (format == 0) { // QCIF
@@ -530 +530 @@
     if (skip_1stop_8data_bits(&s->gb) < 0)
         return AVERROR_INVALIDDATA;
 
     /* H.261 has no I-frames, but if we pass AV_PICTURE_TYPE_I for the first
      * frame, the codec crashes if it does not contain all I-blocks
-     * (e.g. when a packet is lost). */
+     * (e.g. when a packet is lost). We will fix the picture type in the
+     * output frame based on h->freeze_picture_release later. */
     s->pict_type = AV_PICTURE_TYPE_P;
 
     h->gob_number = 0;
     return 0;
 }
@@ -588 +589 @@
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
     H261Context *h     = avctx->priv_data;
     MpegEncContext *s  = &h->s;
     int ret;
+    enum AVPictureType pict_type;
     AVFrame *pict = data;
 
     ff_dlog(avctx, "*****frame %d size=%d\n", avctx->frame_number, buf_size);
     ff_dlog(avctx, "bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
 
@@ -628 +630 @@
             return ret;
 
         goto retry;
     }
 
-    // for skipping the frame
-    s->current_picture.f->pict_type = s->pict_type;
-    s->current_picture.f->key_frame = s->pict_type == AV_PICTURE_TYPE_I;
+    // for skipping the frame and keyframe markup
+    pict_type = h->freeze_picture_release ? AV_PICTURE_TYPE_I : s->pict_type;
 
-    if ((avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type == AV_PICTURE_TYPE_B) ||
-        (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type != AV_PICTURE_TYPE_I) ||
+    if ((avctx->skip_frame >= AVDISCARD_NONREF && pict_type == AV_PICTURE_TYPE_B) ||
+        (avctx->skip_frame >= AVDISCARD_NONKEY && pict_type != AV_PICTURE_TYPE_I) ||
          avctx->skip_frame >= AVDISCARD_ALL)
         return get_consumed_bytes(s, buf_size);
 
+    s->current_picture.f->pict_type = s->pict_type;
+    s->current_picture.f->key_frame = s->pict_type == AV_PICTURE_TYPE_I;
+
     if (ff_mpv_frame_start(s, avctx) < 0)
         return -1;
 
     ff_mpeg_er_frame_start(s);
 
@@ -658 +662 @@
     av_assert0(s->current_picture.f->pict_type == s->current_picture_ptr->f->pict_type);
     av_assert0(s->current_picture.f->pict_type == s->pict_type);
 
     if ((ret = av_frame_ref(pict, s->current_picture_ptr->f)) < 0)
         return ret;
+
+    // fix picture type and correctly mark keyframes
+    pict->pict_type = pict_type;
+    pict->key_frame = pict_type == AV_PICTURE_TYPE_I;
+
     ff_print_debug_info(s, s->current_picture_ptr, pict);
 
     *got_frame = 1;
 
     return get_consumed_bytes(s, buf_size);