diff --git a/fftools/ffmpeg_enc.c b/fftools/ffmpeg_enc.c
index d1dae558e1..c9a12af139 100644
--- a/fftools/ffmpeg_enc.c
+++ b/fftools/ffmpeg_enc.c
@@ -706,6 +706,8 @@ static int encode_frame(OutputFile *of, OutputStream *ost, AVFrame *frame,
                 return ret;
         }
 
+        pkt->flags |= AV_PKT_FLAG_TRUSTED;
+
         if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
             ret = update_video_stats(ost, pkt, !!vstats_filename);
             if (ret < 0)
diff --git a/fftools/ffmpeg_mux.c b/fftools/ffmpeg_mux.c
index 59befefab2..e8e5c677b8 100644
--- a/fftools/ffmpeg_mux.c
+++ b/fftools/ffmpeg_mux.c
@@ -433,6 +433,7 @@ int muxer_thread(void *arg)
 
         ost = of->streams[mux->sch_stream_idx[stream_idx]];
         mt.pkt->stream_index = ost->index;
+        mt.pkt->flags       &= ~AV_PKT_FLAG_TRUSTED;
 
         ret = mux_packet_filter(mux, &mt, ost, ret < 0 ? NULL : mt.pkt, &stream_eof);
         av_packet_unref(mt.pkt);