Codecs: aac: Improve ADTS stream detection

Captured ADTS streams might start from some garbage data from previous frame. We should check for sync errors even for first frame.

Change-Id: I70171298b79713aeedf9fa2e6098a03063487649

2 files changed, 34 insertions, 22 deletions

diff --git a/lib/rbcodec/codecs/libfaad/decoder.c b/lib/rbcodec/codecs/libfaad/decoder.c
index d68d093b0b..533de50d5b 100644
--- a/lib/rbcodec/codecs/libfaad/decoder.c
+++ b/lib/rbcodec/codecs/libfaad/decoder.c
@@ -247,6 +247,7 @@ int32_t NEAACDECAPI NeAACDecInit(NeAACDecHandle hDecoder, uint8_t *buffer,
     if ((hDecoder == NULL) || (samplerate == NULL) || (channels == NULL))
         return -1;
 
+    adts.old_format = hDecoder->config.useOldADTSFormat;
     hDecoder->sf_index = get_sr_index(hDecoder->config.defSampleRate);
     hDecoder->object_type = hDecoder->config.defObjectType;
     *samplerate = get_sample_rate(hDecoder->sf_index);
@@ -277,12 +278,9 @@ int32_t NEAACDECAPI NeAACDecInit(NeAACDecHandle hDecoder, uint8_t *buffer,
             bits = bit2byte(faad_get_processed_bits(&ld));
 
         /* Check if an ADTS header is present */
-        } else if (faad_showbits(&ld, 12) == 0xfff) {
+        } else if (adts_frame(&adts, &ld) == 0) {
             hDecoder->adts_header_present = 1;
 
-            adts.old_format = hDecoder->config.useOldADTSFormat;
-            adts_frame(&adts, &ld);
-
             hDecoder->sf_index = adts.sf_index;
             hDecoder->object_type = adts.profile + 1;
 
diff --git a/lib/rbcodec/metadata/aac.c b/lib/rbcodec/metadata/aac.c
index 372bab716e..c5467f0422 100644
--- a/lib/rbcodec/metadata/aac.c
+++ b/lib/rbcodec/metadata/aac.c
@@ -47,6 +47,24 @@ static bool check_adts_syncword(int fd)
     return (syncword & 0xFFF6) == 0xFFF0;
 }
 
+static bool find_adts_keyword(int fd, struct mp3entry *entry)
+{
+    /* logic is copied from adts_fixed_header libfaad/syntax.c:
+     * try to recover from sync errors */
+    for (int i = 0; i < 768; ++i)
+    {
+        if (-1 == lseek(fd, entry->first_frame_offset + i, SEEK_SET))
+            return false;
+
+        if (check_adts_syncword(fd))
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 bool get_aac_metadata(int fd, struct mp3entry *entry)
 {
     unsigned char buf[5];
@@ -65,8 +83,21 @@ bool get_aac_metadata(int fd, struct mp3entry *entry)
 
     if (-1 == lseek(fd, entry->first_frame_offset, SEEK_SET))
         return false;
+    if (read(fd, buf, 5) != 5)
+        return false;
+    if (!memcmp(buf, "ADIF", 4))
+    {
+        if (-1 == lseek(fd, (buf[4] & 0x80) ? (entry->first_frame_offset + 9) : entry->first_frame_offset, SEEK_SET))
+            return false;
 
-    if (check_adts_syncword(fd))
+        uint32_t bitrate;
+        read_uint32be(fd, &bitrate);
+        entry->vbr = (bitrate & 0x10000000) != 0;
+        entry->bitrate = ((bitrate & 0xFFFFFE0) + 16000) / 32000;
+        read_uint32be(fd, (uint32_t*)(&(entry->frequency)));
+        entry->frequency = sample_rates[(entry->frequency >> (entry->vbr ? 23 : 3)) & 0x0F];
+    }
+    else if (find_adts_keyword(fd, entry))
     {
         int frames;
         int stat_length;
@@ -101,23 +132,6 @@ bool get_aac_metadata(int fd, struct mp3entry *entry)
         }
 #endif
     }
-    else
-    {
-        uint32_t bitrate;
-        if (-1 == lseek(fd, entry->first_frame_offset, SEEK_SET))
-            return false;
-        if (read(fd, buf, 5) != 5)
-            return false;
-        if (memcmp(buf, "ADIF", 4))
-            return false;
-        if (-1 == lseek(fd, (buf[4] & 0x80) ? (entry->first_frame_offset + 9) : entry->first_frame_offset, SEEK_SET))
-            return false;
-        read_uint32be(fd, &bitrate);
-        entry->vbr = (bitrate & 0x10000000) != 0;
-        entry->bitrate = ((bitrate & 0xFFFFFE0) + 16000) / 32000;
-        read_uint32be(fd, (uint32_t*)(&(entry->frequency)));
-        entry->frequency = sample_rates[(entry->frequency >> (entry->vbr ? 23 : 3)) & 0x0F];
-    }
     entry->length = (unsigned long)((entry->filesize * 8LL + (entry->bitrate >> 1)) / entry->bitrate);
 
     return true;