3 files changed, 14 insertions, 3 deletions

diff --git a/apps/codecs/aac.c b/apps/codecs/aac.c
index 4a9c7479f3..4695caab4a 100644
--- a/apps/codecs/aac.c
+++ b/apps/codecs/aac.c
@@ -157,6 +157,12 @@ next_track:
         {
             ci->advance_buffer(file_offset - ci->curpos);
         }
+        else if (file_offset == 0)
+        {
+            LOGF("AAC: get_sample_offset error\n");
+            err = CODEC_ERROR;
+            goto done;
+        }
         
         /* Request the required number of bytes from the input buffer */
         buffer=ci->request_buffer(&n,sample_byte_size);
diff --git a/apps/codecs/libm4a/demux.c b/apps/codecs/libm4a/demux.c
index 34bc07556b..10972f8b1f 100644
--- a/apps/codecs/libm4a/demux.c
+++ b/apps/codecs/libm4a/demux.c
@@ -762,7 +762,11 @@ int qtmovie_read(stream_t *file, demux_res_t *demux_res)
             read_chunk_mdat(&qtmovie, chunk_len);
             /* Keep track of start of stream in file - used for seeking */
             qtmovie.res->mdat_offset=stream_tell(qtmovie.stream);
-            return 1;
+            /* There can be empty mdats before the real one. If so, skip them */
+            if (qtmovie.res->mdat_len > 0) {
+                return 1;
+            }
+            break;
 
             /*  these following atoms can be skipped !!!! */
         case MAKEFOURCC('f','r','e','e'):
diff --git a/apps/codecs/libm4a/m4a.c b/apps/codecs/libm4a/m4a.c
index 0a87ec35ea..f5aaeca302 100644
--- a/apps/codecs/libm4a/m4a.c
+++ b/apps/codecs/libm4a/m4a.c
@@ -199,7 +199,7 @@ unsigned int get_sample_offset(demux_res_t *demux_res, uint32_t sample)
         prev_chunk_samples = demux_res->sample_to_chunk[i].num_samples;
     }
 
-    if (demux_res->num_sample_to_chunks > 1)
+    if (sample >= demux_res->sample_to_chunk[0].num_samples)
     {
         chunk = prev_chunk + (sample - total_samples) / prev_chunk_samples;
     }
@@ -223,7 +223,8 @@ unsigned int get_sample_offset(demux_res_t *demux_res, uint32_t sample)
         file_offset = demux_res->chunk_offset[chunk - 1];
     }
     
-    if (chunk_sample > sample) {
+    if (chunk_sample > sample) 
+    {
         return 0;
     }