lavc/encode: pass through frame durations to encoded packets

The generic code can only handle the no-delay case. Encoders with delay
need to be handled individually, which will be done in the following
commits.

1 files changed, 12 insertions, 2 deletions

diff --git a/libavcodec/encode.c b/libavcodec/encode.c
index da910b1b60..76eb69bba8 100644
--- a/libavcodec/encode.c
+++ b/libavcodec/encode.c
@@ -230,10 +230,13 @@ static int encode_simple_internal(AVCodecContext *avctx, AVPacket *avpkt)
             if (avpkt->pts == AV_NOPTS_VALUE)
                 avpkt->pts = frame->pts;
 
-            if (avctx->codec->type == AVMEDIA_TYPE_AUDIO) {
-                if (!avpkt->duration)
+            if (!avpkt->duration) {
+                if (frame->duration)
+                    avpkt->duration = frame->duration;
+                else if (avctx->codec->type == AVMEDIA_TYPE_AUDIO) {
                     avpkt->duration = ff_samples_to_time_base(avctx,
                                                               frame->nb_samples);
+                }
             }
         }
 
@@ -424,6 +427,13 @@ FF_ENABLE_DEPRECATION_WARNINGS
             return ret;
     }
 
+    // only use the frame duration if the timebase is set;
+    // otherwise we cannot be sure that whatever value it has is in the right
+    // timebase, so we would produce an incorrect value, which is worse than
+    // none at all
+    if (!dst->time_base.num || !dst->time_base.den)
+        dst->duration = 0;
+
     return 0;
 }