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remove redundancy in AC-3 parser by using common tables from ac3tab.h

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Originally committed as revision 8318 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-03-11 02:13:05 +00:00
parent 755c18ae5d
commit 050aa8b9bc
5 changed files with 42 additions and 65 deletions
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13
libavcodec/ac3.c
View File

@ -181,6 +181,11 @@ void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap,
} while (end > bndtab[j++]);
}
/**
* Initializes some tables.
* note: This function must remain thread safe because it is called by the
* AVParser init code.
*/
void ac3_common_init(void)
{
int i, j, k, l, v;
@ -194,4 +199,12 @@ void ac3_common_init(void)
l += v;
}
bndtab[50] = l;
/* generate ff_ac3_frame_sizes table */
for(i=0; i<38; i++) {
int br = ff_ac3_bitratetab[i >> 1];
ff_ac3_frame_sizes[i][0] = ( 2*br );
ff_ac3_frame_sizes[i][1] = (320*br / 147) + (i & 1);
ff_ac3_frame_sizes[i][2] = ( 3*br );
}
}

2
libavcodec/ac3.h
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@ -45,6 +45,8 @@ typedef struct AC3BitAllocParameters {
int cplfleak, cplsleak;
} AC3BitAllocParameters;
extern uint16_t ff_ac3_frame_sizes[38][3];
extern const uint8_t ff_ac3_channels[8];
extern const uint16_t ff_ac3_freqs[3];
extern const uint16_t ff_ac3_bitratetab[19];
extern const int16_t ff_ac3_window[256];

6
libavcodec/ac3enc.c
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@ -611,6 +611,8 @@ static int AC3_encode_init(AVCodecContext *avctx)
avctx->frame_size = AC3_FRAME_SIZE;
ac3_common_init();
/* number of channels */
if (channels < 1 || channels > 6)
return -1;
@ -644,7 +646,7 @@ static int AC3_encode_init(AVCodecContext *avctx)
return -1;
s->bit_rate = bitrate;
s->frmsizecod = i << 1;
s->frame_size_min = (bitrate * 1000 * AC3_FRAME_SIZE) / (freq * 16);
s->frame_size_min = ff_ac3_frame_sizes[s->frmsizecod][s->fscod];
s->bits_written = 0;
s->samples_written = 0;
s->frame_size = s->frame_size_min;
@ -663,8 +665,6 @@ static int AC3_encode_init(AVCodecContext *avctx)
/* initial snr offset */
s->csnroffst = 40;
ac3_common_init();
/* mdct init */
fft_init(MDCT_NBITS - 2);
for(i=0;i<N/4;i++) {

14
libavcodec/ac3tab.h
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@ -24,6 +24,20 @@
* tables taken directly from AC3 spec.
*/
/**
* Possible frame sizes.
* Generated at runtime to match ATSC A/52 Table 5.18 Frame Size Code Table.
*/
uint16_t ff_ac3_frame_sizes[38][3];
/**
* Maps audio coding mode (acmod) to number of full-bandwidth channels.
* from ATSC A/52 Table 5.8 Audio Coding Mode
*/
const uint8_t ff_ac3_channels[8] = {
2, 1, 2, 3, 3, 4, 4, 5
};
/* possible frequencies */
const uint16_t ff_ac3_freqs[3] = { 48000, 44100, 32000 };

72
libavcodec/parser.c
View File

@ -22,6 +22,7 @@
#include "avcodec.h"
#include "mpegvideo.h"
#include "mpegaudio.h"
#include "ac3.h"
#include "parser.h"
AVCodecParser *av_first_parser = NULL;
@ -581,60 +582,6 @@ typedef struct AC3ParseContext {
#define AAC_HEADER_SIZE 7
#ifdef CONFIG_AC3_PARSER
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 uint8_t ac3_channels[8] = {
2, 1, 2, 3, 3, 4, 4, 5
};
static const uint8_t eac3_blocks[4] = {
1, 2, 3, 6
@ -672,7 +619,7 @@ static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
fscod = get_bits(&bits, 2);
frmsizecod = get_bits(&bits, 6);
if(fscod == 3)
if(fscod == 3 && frmsizecod > 37)
return 0;
skip_bits(&bits, 5); /* bsid */
@ -687,12 +634,12 @@ static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
lfeon = get_bits1(&bits);
halfratecod = FFMAX(bsid, 8) - 8;
*sample_rate = ac3_sample_rates[fscod] >> halfratecod;
*bit_rate = (ac3_bitrates[frmsizecod] * 1000) >> halfratecod;
*channels = ac3_channels[acmod] + lfeon;
*sample_rate = ff_ac3_freqs[fscod] >> halfratecod;
*bit_rate = (ff_ac3_bitratetab[frmsizecod] * 1000) >> halfratecod;
*channels = ff_ac3_channels[acmod] + lfeon;
*samples = 6 * 256;
return ac3_frame_sizes[frmsizecod][fscod] * 2;
return ff_ac3_frame_sizes[frmsizecod][fscod] * 2;
} else if (bsid > 10 && bsid <= 16) { /* Enhanced AC-3 */
strmtyp = get_bits(&bits, 2);
substreamid = get_bits(&bits, 3);
@ -709,11 +656,11 @@ static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
if(fscod2 == 3)
return 0;
*sample_rate = ac3_sample_rates[fscod2] / 2;
*sample_rate = ff_ac3_freqs[fscod2] / 2;
} else {
numblkscod = get_bits(&bits, 2);
*sample_rate = ac3_sample_rates[fscod];
*sample_rate = ff_ac3_freqs[fscod];
}
acmod = get_bits(&bits, 3);
@ -721,7 +668,7 @@ static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
*samples = eac3_blocks[numblkscod] * 256;
*bit_rate = frmsiz * (*sample_rate) * 16 / (*samples);
*channels = ac3_channels[acmod] + lfeon;
*channels = ff_ac3_channels[acmod] + lfeon;
return frmsiz * 2;
}
@ -780,6 +727,7 @@ static int ac3_parse_init(AVCodecParserContext *s1)
s->inbuf_ptr = s->inbuf;
s->header_size = AC3_HEADER_SIZE;
s->sync = ac3_sync;
ac3_common_init();
return 0;
}
#endif