native ac3 parser

Originally committed as revision 4878 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 96 insertions, 26 deletions

diff --git a/libavcodec/parser.c b/libavcodec/parser.c
index a21c6cfe30..9d424e9438 100644
--- a/libavcodec/parser.c
+++ b/libavcodec/parser.c
@@ -748,24 +748,106 @@ static int mpegaudio_parse(AVCodecParserContext *s1,
     return buf_ptr - buf;
 }
 
-#ifdef CONFIG_AC3
-#ifdef CONFIG_A52BIN
-extern int ff_a52_syncinfo (AVCodecContext * avctx, const uint8_t * buf,
-                       int * flags, int * sample_rate, int * bit_rate);
-#else
-extern int a52_syncinfo (const uint8_t * buf, int * flags,
-                         int * sample_rate, int * bit_rate);
-#endif
-
 typedef struct AC3ParseContext {
     uint8_t inbuf[4096]; /* input buffer */
     uint8_t *inbuf_ptr;
     int frame_size;
-    int flags;
 } AC3ParseContext;
 
 #define AC3_HEADER_SIZE 7
-#define A52_LFE 16
+
+static const int ac3_sample_rates[4] = {
+    48000, 44100, 32000, 0
+};
+
+static const int ac3_frame_sizes[64][3] = {
+    { 64,   69,   96   },  
+    { 64,   70,   96   },  
+    { 80,   87,   120  },  
+    { 80,   88,   120  },  
+    { 96,   104,  144  },  
+    { 96,   105,  144  },  
+    { 112,  121,  168  }, 
+    { 112,  122,  168  }, 
+    { 128,  139,  192  }, 
+    { 128,  140,  192  }, 
+    { 160,  174,  240  }, 
+    { 160,  175,  240  }, 
+    { 192,  208,  288  }, 
+    { 192,  209,  288  }, 
+    { 224,  243,  336  }, 
+    { 224,  244,  336  }, 
+    { 256,  278,  384  }, 
+    { 256,  279,  384  }, 
+    { 320,  348,  480  }, 
+    { 320,  349,  480  }, 
+    { 384,  417,  576  }, 
+    { 384,  418,  576  }, 
+    { 448,  487,  672  }, 
+    { 448,  488,  672  }, 
+    { 512,  557,  768  }, 
+    { 512,  558,  768  }, 
+    { 640,  696,  960  }, 
+    { 640,  697,  960  }, 
+    { 768,  835,  1152 }, 
+    { 768,  836,  1152 }, 
+    { 896,  975,  1344 }, 
+    { 896,  976,  1344 }, 
+    { 1024, 1114, 1536 },
+    { 1024, 1115, 1536 },
+    { 1152, 1253, 1728 },
+    { 1152, 1254, 1728 },
+    { 1280, 1393, 1920 },
+    { 1280, 1394, 1920 },
+};
+
+static const int ac3_bitrates[64] = {
+    32, 32, 40, 40, 48, 48, 56, 56, 64, 64, 80, 80, 96, 96, 112, 112,
+    128, 128, 160, 160, 192, 192, 224, 224, 256, 256, 320, 320, 384,
+    384, 448, 448, 512, 512, 576, 576, 640, 640,
+};
+
+static const int ac3_channels[8] = {
+    2, 1, 2, 3, 3, 4, 4, 5
+};
+
+static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
+		    int *bit_rate)
+{
+    unsigned int fscod, frmsizecod, acmod, bsid, lfeon;
+    GetBitContext bits;
+
+    init_get_bits(&bits, buf, AC3_HEADER_SIZE * 8);
+
+    if(get_bits(&bits, 16) != 0x0b77)
+	return 0;
+
+    get_bits(&bits, 16);	/* crc */
+    fscod = get_bits(&bits, 2);
+    frmsizecod = get_bits(&bits, 6);
+
+    if(!ac3_sample_rates[fscod])
+	return 0;
+
+    bsid = get_bits(&bits, 5);
+    if(bsid > 8)
+	return 0;
+    get_bits(&bits, 3);	/* bsmod */
+    acmod = get_bits(&bits, 3);
+    if(acmod & 1 && acmod != 1)
+	get_bits(&bits, 2); /* cmixlev */
+    if(acmod & 4)
+	get_bits(&bits, 2); /* surmixlev */
+    if(acmod & 2)
+	get_bits(&bits, 2); /* dsurmod */
+    lfeon = get_bits(&bits, 1);
+
+    *sample_rate = ac3_sample_rates[fscod];
+    *bit_rate = ac3_bitrates[frmsizecod] * 1000;
+    *channels = ac3_channels[acmod] + lfeon;
+
+    return ac3_frame_sizes[frmsizecod][fscod] * 2;
+}
 
 static int ac3_parse_init(AVCodecParserContext *s1)
 {
@@ -781,10 +863,7 @@ static int ac3_parse(AVCodecParserContext *s1,
 {
     AC3ParseContext *s = s1->priv_data;
     const uint8_t *buf_ptr;
-    int len, sample_rate, bit_rate;
-    static const int ac3_channels[8] = {
-        2, 1, 2, 3, 3, 4, 4, 5
-    };
+    int len, sample_rate, bit_rate, channels;
 
     *poutbuf = NULL;
     *poutbuf_size = 0;
@@ -802,11 +881,7 @@ static int ac3_parse(AVCodecParserContext *s1,
             s->inbuf_ptr += len;
             buf_size -= len;
             if ((s->inbuf_ptr - s->inbuf) == AC3_HEADER_SIZE) {
-#ifdef CONFIG_A52BIN
-                len = ff_a52_syncinfo(avctx, s->inbuf, &s->flags, &sample_rate, &bit_rate);
-#else
-                len = a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
-#endif
+		len = ac3_sync(s->inbuf, &channels, &sample_rate, &bit_rate);
                 if (len == 0) {
                     /* no sync found : move by one byte (inefficient, but simple!) */
                     memmove(s->inbuf, s->inbuf + 1, AC3_HEADER_SIZE - 1);
@@ -817,9 +892,7 @@ static int ac3_parse(AVCodecParserContext *s1,
                     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){
-                        avctx->channels = ac3_channels[s->flags & 7];
-                        if (s->flags & A52_LFE)
-                            avctx->channels++;
+			avctx->channels = channels;
                     }
                     avctx->bit_rate = bit_rate;
                     avctx->frame_size = 6 * 256;
@@ -844,7 +917,6 @@ static int ac3_parse(AVCodecParserContext *s1,
     }
     return buf_ptr - buf;
 }
-#endif
 
 AVCodecParser mpegvideo_parser = {
     { CODEC_ID_MPEG1VIDEO, CODEC_ID_MPEG2VIDEO },
@@ -872,7 +944,6 @@ AVCodecParser mpegaudio_parser = {
     NULL,
 };
 
-#ifdef CONFIG_AC3
 AVCodecParser ac3_parser = {
     { CODEC_ID_AC3 },
     sizeof(AC3ParseContext),
@@ -880,4 +951,3 @@ AVCodecParser ac3_parser = {
     ac3_parse,
     NULL,
 };
-#endif