Move AC3 header parsing code together with the rest of the AC3 parsing code.

Originally committed as revision 8739 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 50 insertions, 1 deletions

diff --git a/libavcodec/parser.c b/libavcodec/parser.c
index 1c21d50fe5..6b0b98f948 100644
--- a/libavcodec/parser.c
+++ b/libavcodec/parser.c
@@ -22,7 +22,6 @@
 #include "avcodec.h"
 #include "mpegvideo.h"
 #include "mpegaudio.h"
-#include "ac3.h"
 #include "parser.h"
 
 AVCodecParser *av_first_parser = NULL;
@@ -605,6 +604,56 @@ static const int aac_channels[8] = {
 #endif
 
 #ifdef CONFIG_AC3_PARSER
+int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr)
+{
+    GetBitContext gbc;
+
+    memset(hdr, 0, sizeof(*hdr));
+
+    init_get_bits(&gbc, buf, 54);
+
+    hdr->sync_word = get_bits(&gbc, 16);
+    if(hdr->sync_word != 0x0B77)
+        return -1;
+
+    /* read ahead to bsid to make sure this is AC-3, not E-AC-3 */
+    hdr->bsid = show_bits_long(&gbc, 29) & 0x1F;
+    if(hdr->bsid > 10)
+        return -2;
+
+    hdr->crc1 = get_bits(&gbc, 16);
+    hdr->fscod = get_bits(&gbc, 2);
+    if(hdr->fscod == 3)
+        return -3;
+
+    hdr->frmsizecod = get_bits(&gbc, 6);
+    if(hdr->frmsizecod > 37)
+        return -4;
+
+    skip_bits(&gbc, 5); // skip bsid, already got it
+
+    hdr->bsmod = get_bits(&gbc, 3);
+    hdr->acmod = get_bits(&gbc, 3);
+    if((hdr->acmod & 1) && hdr->acmod != 1) {
+        hdr->cmixlev = get_bits(&gbc, 2);
+    }
+    if(hdr->acmod & 4) {
+        hdr->surmixlev = get_bits(&gbc, 2);
+    }
+    if(hdr->acmod == 2) {
+        hdr->dsurmod = get_bits(&gbc, 2);
+    }
+    hdr->lfeon = get_bits1(&gbc);
+
+    hdr->halfratecod = FFMAX(hdr->bsid, 8) - 8;
+    hdr->sample_rate = ff_ac3_freqs[hdr->fscod] >> hdr->halfratecod;
+    hdr->bit_rate = (ff_ac3_bitratetab[hdr->frmsizecod>>1] * 1000) >> hdr->halfratecod;
+    hdr->channels = ff_ac3_channels[hdr->acmod] + hdr->lfeon;
+    hdr->frame_size = ff_ac3_frame_sizes[hdr->frmsizecod][hdr->fscod] * 2;
+
+    return 0;
+}
+
 static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
                     int *bit_rate, int *samples)
 {