h264: derive the delay from the level when it's not present

Fall back to maximum DPB size if the level is unknown.

This should be more spec-compliant and does not depend on the caller
setting has_b_frames before opening the decoder.

The old behaviour, when the delay is supplied by the caller setting
has_b_frames, can still be obtained by setting strict_std_compliance
below normal.

1 files changed, 4 insertions, 11 deletions

diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index ec57d6d2f7..6b12b303d7 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -851,18 +851,11 @@ static void decode_postinit(H264Context *h, int setup_finished)
     // FIXME do something with unavailable reference frames
 
     /* Sort B-frames into display order */
-
-    if (h->sps.bitstream_restriction_flag &&
-        h->avctx->has_b_frames < h->sps.num_reorder_frames) {
-        h->avctx->has_b_frames = h->sps.num_reorder_frames;
-        h->low_delay           = 0;
-    }
-
-    if (h->avctx->strict_std_compliance >= FF_COMPLIANCE_STRICT &&
-        !h->sps.bitstream_restriction_flag) {
-        h->avctx->has_b_frames = MAX_DELAYED_PIC_COUNT - 1;
-        h->low_delay           = 0;
+    if (h->sps.bitstream_restriction_flag ||
+        h->avctx->strict_std_compliance >= FF_COMPLIANCE_NORMAL) {
+        h->avctx->has_b_frames = FFMAX(h->avctx->has_b_frames, h->sps.num_reorder_frames);
     }
+    h->low_delay = !h->avctx->has_b_frames;
 
     pics = 0;
     while (h->delayed_pic[pics])