adts aac parser

Originally committed as revision 4954 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 90 insertions, 9 deletions

diff --git a/libavcodec/parser.c b/libavcodec/parser.c
index 412cd83594..2c896d85c8 100644
--- a/libavcodec/parser.c
+++ b/libavcodec/parser.c
@@ -727,13 +727,18 @@ static int mpegaudio_parse(AVCodecParserContext *s1,
     return buf_ptr - buf;
 }
 
+/* also used for ADTS AAC */
 typedef struct AC3ParseContext {
     uint8_t inbuf[4096]; /* input buffer */
     uint8_t *inbuf_ptr;
     int frame_size;
+    int header_size;
+    int (*sync)(const uint8_t *buf, int *channels, int *sample_rate,
+                int *bit_rate, int *samples);
 } AC3ParseContext;
 
 #define AC3_HEADER_SIZE 7
+#define AAC_HEADER_SIZE 8
 
 static const int ac3_sample_rates[4] = {
     48000, 44100, 32000, 0
@@ -790,8 +795,17 @@ static const int ac3_channels[8] = {
     2, 1, 2, 3, 3, 4, 4, 5
 };
 
+static int aac_sample_rates[16] = {
+    96000, 88200, 64000, 48000, 44100, 32000,
+    24000, 22050, 16000, 12000, 11025, 8000, 7350
+};
+
+static int aac_channels[8] = {
+    0, 1, 2, 3, 4, 5, 6, 8
+};
+
 static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
-                    int *bit_rate)
+                    int *bit_rate, int *samples)
 {
     unsigned int fscod, frmsizecod, acmod, bsid, lfeon;
     GetBitContext bits;
@@ -824,17 +838,70 @@ static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
     *sample_rate = ac3_sample_rates[fscod];
     *bit_rate = ac3_bitrates[frmsizecod] * 1000;
     *channels = ac3_channels[acmod] + lfeon;
+    *samples = 6 * 256;
 
     return ac3_frame_sizes[frmsizecod][fscod] * 2;
 }
 
+static int aac_sync(const uint8_t *buf, int *channels, int *sample_rate,
+                    int *bit_rate, int *samples)
+{
+    GetBitContext bits;
+    int size, rdb, ch, sr;
+
+    init_get_bits(&bits, buf, AAC_HEADER_SIZE * 8);
+
+    if(get_bits(&bits, 12) != 0xfff)
+        return 0;
+
+    get_bits(&bits, 1);
+    get_bits(&bits, 2);
+    get_bits(&bits, 1);         /* protection_absent */
+    get_bits(&bits, 2);
+    sr = get_bits(&bits, 4);
+    if(!aac_sample_rates[sr])
+        return 0;
+    get_bits(&bits, 1);         /* private_bit */
+    ch = get_bits(&bits, 3);
+    if(!aac_channels[ch])
+        return 0;
+    get_bits(&bits, 1);         /* original/copy */
+    get_bits(&bits, 1);         /* home */
+
+    /* adts_variable_header */
+    get_bits(&bits, 1);         /* copyright_identification_bit */
+    get_bits(&bits, 1);         /* copyright_identification_start */
+    size = get_bits(&bits, 13);
+    get_bits(&bits, 11);        /* adts_buffer_fullness */
+    rdb = get_bits(&bits, 2);
+
+    *channels = aac_channels[ch];
+    *sample_rate = aac_sample_rates[sr];
+    *samples = (rdb + 1) * 1024;
+    *bit_rate = size * 8 * *sample_rate / *samples;
+
+    return size;
+}
+
 static int ac3_parse_init(AVCodecParserContext *s1)
 {
     AC3ParseContext *s = s1->priv_data;
     s->inbuf_ptr = s->inbuf;
+    s->header_size = AC3_HEADER_SIZE;
+    s->sync = ac3_sync;
     return 0;
 }
 
+static int aac_parse_init(AVCodecParserContext *s1)
+{
+    AC3ParseContext *s = s1->priv_data;
+    s->inbuf_ptr = s->inbuf;
+    s->header_size = AAC_HEADER_SIZE;
+    s->sync = aac_sync;
+    return 0;
+}
+
+/* also used for ADTS AAC */
 static int ac3_parse(AVCodecParserContext *s1,
                      AVCodecContext *avctx,
                      uint8_t **poutbuf, int *poutbuf_size,
@@ -842,7 +909,7 @@ static int ac3_parse(AVCodecParserContext *s1,
 {
     AC3ParseContext *s = s1->priv_data;
     const uint8_t *buf_ptr;
-    int len, sample_rate, bit_rate, channels;
+    int len, sample_rate, bit_rate, channels, samples;
 
     *poutbuf = NULL;
     *poutbuf_size = 0;
@@ -851,29 +918,35 @@ static int ac3_parse(AVCodecParserContext *s1,
     while (buf_size > 0) {
         len = s->inbuf_ptr - s->inbuf;
         if (s->frame_size == 0) {
-            /* no header seen : find one. We need at least 7 bytes to parse it */
-            len = FFMIN(AC3_HEADER_SIZE - len, buf_size);
+            /* no header seen : find one. We need at least s->header_size
+               bytes to parse it */
+            len = FFMIN(s->header_size - len, buf_size);
 
             memcpy(s->inbuf_ptr, buf_ptr, len);
             buf_ptr += len;
             s->inbuf_ptr += len;
             buf_size -= len;
-            if ((s->inbuf_ptr - s->inbuf) == AC3_HEADER_SIZE) {
-                len = ac3_sync(s->inbuf, &channels, &sample_rate, &bit_rate);
+            if ((s->inbuf_ptr - s->inbuf) == s->header_size) {
+                len = s->sync(s->inbuf, &channels, &sample_rate, &bit_rate,
+                              &samples);
                 if (len == 0) {
                     /* no sync found : move by one byte (inefficient, but simple!) */
-                    memmove(s->inbuf, s->inbuf + 1, AC3_HEADER_SIZE - 1);
+                    memmove(s->inbuf, s->inbuf + 1, s->header_size - 1);
                     s->inbuf_ptr--;
                 } else {
                     s->frame_size = len;
                     /* update codec info */
                     avctx->sample_rate = sample_rate;
                     /* set channels,except if the user explicitly requests 1 or 2 channels, XXX/FIXME this is a bit ugly */
-                    if(avctx->channels!=1 && avctx->channels!=2){
+                    if(avctx->codec_id == CODEC_ID_AC3){
+                        if(avctx->channels!=1 && avctx->channels!=2){
+                            avctx->channels = channels;
+                        }
+                    } else {
                         avctx->channels = channels;
                     }
                     avctx->bit_rate = bit_rate;
-                    avctx->frame_size = 6 * 256;
+                    avctx->frame_size = samples;
                 }
             }
         } else {
@@ -929,3 +1002,11 @@ AVCodecParser ac3_parser = {
     ac3_parse,
     NULL,
 };
+
+AVCodecParser aac_parser = {
+    { CODEC_ID_AAC },
+    sizeof(AC3ParseContext),
+    aac_parse_init,
+    ac3_parse,
+    NULL,
+};