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shorten: move decoding of prediction order and applying of global offset to 

decode_subframe_lpc().
This commit is contained in:
Justin Ruggles 2011-09-14 19:16:14 -04:00
parent 0f97c5014b
commit fe31a637f1
1 changed files with 27 additions and 17 deletions
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44
libavcodec/shorten.c
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@ -260,20 +260,41 @@ static int16_t * interleave_buffer(int16_t *samples, int nchan, int blocksize, i
return samples;
}
static void decode_subframe_lpc(ShortenContext *s, int channel, int residual_size, int pred_order)
static int decode_subframe_lpc(ShortenContext *s, int channel,
int residual_size, int32_t coffset)
{
int sum, i, j;
int pred_order, sum, i, j;
int *coeffs = s->coeffs;
/* read/validate prediction order */
pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE);
if (pred_order > s->nwrap) {
av_log(s->avctx, AV_LOG_ERROR, "invalid pred_order %d\n", pred_order);
return AVERROR(EINVAL);
}
/* read LPC coefficients */
for (i=0; i<pred_order; i++)
coeffs[i] = get_sr_golomb_shorten(&s->gb, LPCQUANT);
/* subtract offset from previous samples to use in prediction */
if (coffset)
for (i = -pred_order; i < 0; i++)
s->decoded[channel][i] -= coffset;
/* decode residual and do LPC prediction */
for (i=0; i < s->blocksize; i++) {
sum = s->lpcqoffset;
for (j=0; j<pred_order; j++)
sum += coeffs[j] * s->decoded[channel][i-j-1];
s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + (sum >> LPCQUANT);
}
/* add offset to current samples */
if (coffset != 0)
for (i = 0; i < s->blocksize; i++)
s->decoded[channel][i] += coffset;
return 0;
}
static int read_header(ShortenContext *s)
@ -429,6 +450,7 @@ static int shorten_decode_frame(AVCodecContext *avctx,
*data_size = 0;
} else {
/* process audio command */
int ret;
int residual_size = 0;
int channel = s->cur_chan;
int32_t coffset;
@ -474,21 +496,9 @@ static int shorten_decode_frame(AVCodecContext *avctx,
+ s->decoded[channel][i-3];
break;
case FN_QLPC:
{
int pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE);
if (pred_order > s->nwrap) {
av_log(avctx, AV_LOG_ERROR,
"invalid pred_order %d\n",
pred_order);
return -1;
}
for (i=0; i<pred_order; i++)
s->decoded[channel][i - pred_order] -= coffset;
decode_subframe_lpc(s, channel, residual_size, pred_order);
if (coffset != 0)
for (i=0; i < s->blocksize; i++)
s->decoded[channel][i] += coffset;
}
if ((ret = decode_subframe_lpc(s, channel, residual_size, coffset)) < 0)
return ret;
break;
}
if (s->nmean > 0) {
int32_t sum = (s->version < 2) ? 0 : s->blocksize / 2;