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use bytestream reader instead of bitstream for THP

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5% smaller adpcm.o
20% faster

Originally committed as revision 8657 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2007-04-07 22:04:33 +00:00
parent 8e952e4d23
commit 949ed6bb30
1 changed files with 11 additions and 12 deletions
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23
libavcodec/adpcm.c
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@ -20,6 +20,7 @@
*/
#include "avcodec.h"
#include "bitstream.h"
#include "bytestream.h"
/**
* @file adpcm.c
@ -1317,7 +1318,6 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
break;
case CODEC_ID_ADPCM_THP:
{
GetBitContext gb;
int table[2][16];
unsigned int samplecnt;
int prev[2][2];
@ -1328,18 +1328,15 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
return -1;
}
init_get_bits(&gb, src, buf_size * 8);
src += buf_size;
get_bits_long(&gb, 32); /* Channel size */
samplecnt = get_bits_long(&gb, 32);
src+=4;
samplecnt = bytestream_get_be32(&src);
for (i = 0; i < 32; i++)
table[0][i] = get_sbits(&gb, 16);
table[0][i] = (int16_t)bytestream_get_be16(&src);
/* Initialize the previous sample. */
for (i = 0; i < 4; i++)
prev[0][i] = get_sbits(&gb, 16);
prev[0][i] = (int16_t)bytestream_get_be16(&src);
if (samplecnt >= (samples_end - samples) / (st + 1)) {
av_log(avctx, AV_LOG_ERROR, "allocated output buffer is too small\n");
@ -1351,17 +1348,19 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
/* Read in every sample for this channel. */
for (i = 0; i < samplecnt / 14; i++) {
int index = get_bits (&gb, 4) & 7;
unsigned int exp = get_bits (&gb, 4);
int index = (*src >> 4) & 7;
unsigned int exp = 28 - (*src++ & 15);
int factor1 = table[ch][index * 2];
int factor2 = table[ch][index * 2 + 1];
/* Decode 14 samples. */
for (n = 0; n < 14; n++) {
int sampledat = get_sbits (&gb, 4);
int32_t sampledat;
if(n&1) sampledat= *src++ <<28;
else sampledat= (*src&0xF0)<<24;
*samples = ((prev[ch][0]*factor1
+ prev[ch][1]*factor2) >> 11) + (sampledat << exp);
+ prev[ch][1]*factor2) >> 11) + (sampledat>>exp);
prev[ch][1] = prev[ch][0];
prev[ch][0] = *samples++;