@@ -566,6 +566,25 @@ static int get_cluster_duration(MOVTrack *track, int cluster_idx)

     return next_dts - track->cluster[cluster_idx].dts;

 }

+static int get_samples_per_packet(MOVTrack *track)

+{

+    int i, first_duration;

+

+    /* use 1 for raw PCM */

+    if (!track->audio_vbr)

+        return 1;

+

+    /* check to see if duration is constant for all clusters */

+    if (!track->entry)

+        return 0;

+    first_duration = get_cluster_duration(track, 0);

+    for (i = 1; i < track->entry; i++) {

+        if (get_cluster_duration(track, i) != first_duration)

+            return 0;

+    }

+    return first_duration;

+}

+

 static int mov_write_audio_tag(AVIOContext *pb, MOVTrack *track)

 {

     int64_t pos = avio_tell(pb);

@@ -602,7 +621,7 @@ static int mov_write_audio_tag(AVIOContext *pb, MOVTrack *track)

         avio_wb32(pb, av_get_bits_per_sample(track->enc->codec_id));

         avio_wb32(pb, mov_get_lpcm_flags(track->enc->codec_id));

         avio_wb32(pb, track->sample_size);

-        avio_wb32(pb, track->audio_vbr ? track->enc->frame_size : 1);

+        avio_wb32(pb, get_samples_per_packet(track));

     } else {

         /* reserved for mp4/3gp */

         avio_wb16(pb, 2);

@@ -3112,10 +3131,6 @@ static int mov_write_header(AVFormatContext *s)

             }

             /* set audio_vbr for compressed audio */

             if (av_get_bits_per_sample(st->codec->codec_id) < 8) {

-                if (!st->codec->frame_size && track->mode == MODE_MOV) {

-                    av_log(s, AV_LOG_ERROR, "track %d: codec frame size is not set\n", i);

-                    goto error;

-                }

                 track->audio_vbr = 1;

             }

             if (track->mode != MODE_MOV) {