diff --git a/src/mp4/moof.c b/src/mp4/moof.c
index 8e625c4..ce39198 100644
--- a/src/mp4/moof.c
+++ b/src/mp4/moof.c
@@ -259,7 +259,7 @@ write_tfdt(struct BitBuf *ptr, const uint64_t base_media_decode_time, char is_au
     else
         pos_video_media_decode_time = ptr->offset;
     err = put_u64_be(ptr, base_media_decode_time);
-    chk_err; // 4 baseMediaDecodeTime
+    chk_err; // 8 baseMediaDecodeTime
     err = put_u32_be_to_offset(ptr, start_atom, ptr->offset - start_atom);
     chk_err;
     return BUF_OK;
diff --git a/src/mp4/mp4.c b/src/mp4/mp4.c
index 33dc3d9..aabc355 100644
--- a/src/mp4/mp4.c
+++ b/src/mp4/mp4.c
@@ -106,7 +106,7 @@ enum BufError mp4_set_slice(const char *nal_data, const uint32_t nal_len,
     samples_info[0].duration = default_sample_size;
     samples_info[0].flags = is_iframe ? 0 : 65536;
     samples_info[1].size = buf_aud.offset;
-    samples_info[1].duration = default_sample_size;
+    samples_info[1].duration = 1152 * buf_aud.offset / aud_framesize;
 
     buf_moof.offset = 0;
     err = write_moof(