@@ -419,9 +419,13 @@ static int64_t dv_frame_offset(AVFormatContext *s, DVDemuxContext *c,

 void ff_dv_offset_reset(DVDemuxContext *c, int64_t frame_offset)

 {

     c->frames= frame_offset;

-    if (c->ach)

+    if (c->ach) {

+        if (c->sys) {

         c->abytes= av_rescale_q(c->frames, c->sys->time_base,

                                 (AVRational){8, c->ast[0]->codec->bit_rate});

+        }else

+            av_log(c->fctx, AV_LOG_ERROR, "cannot adjust audio bytes\n");

+    }

     c->audio_pkt[0].size = c->audio_pkt[1].size = 0;

     c->audio_pkt[2].size = c->audio_pkt[3].size = 0;

 }