stdin

diff --git a/libavformat/mux.c b/libavformat/mux.c
index 9848899..9bdf52d 100644
--- a/libavformat/mux.c
+++ b/libavformat/mux.c
@@ -1090,6 +1090,16 @@ int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt)
             }
         }
 
+        if (!st->internal->avctx->extradata && st->codecpar->extradata) {
+            int size = st->codecpar->extradata_size;
+            if (size < 0 || size >= INT32_MAX - AV_INPUT_BUFFER_PADDING_SIZE)
+                return AVERROR(EINVAL);
+            st->internal->avctx->extradata = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
+            if (!st->internal->avctx->extradata)
+                return AVERROR(ENOMEM);
+            st->internal->avctx->extradata_size = size;
+            memcpy(st->internal->avctx->extradata, st->codecpar->extradata, size);
+        }
         av_apply_bitstream_filters(st->internal->avctx, pkt, st->internal->bsfc);
         if (pkt->size == 0 && pkt->side_data_elems == 0)
             return 0;