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shorten: merge decoding of FN_DIFF* subblocks into decode_subframe_lpc()

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This commit is contained in:
Justin Ruggles 2011-09-16 15:55:27 -04:00
parent 034f42dfce
commit 15d146c958
1 changed files with 38 additions and 43 deletions
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81
libavcodec/shorten.c
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@ -267,37 +267,54 @@ static int16_t * interleave_buffer(int16_t *samples, int nchan, int blocksize, i
return samples;
}
static int decode_subframe_lpc(ShortenContext *s, int channel,
static const int fixed_coeffs[3][3] = {
{ 1, 0, 0 },
{ 2, -1, 0 },
{ 3, -3, 1 }
};
static int decode_subframe_lpc(ShortenContext *s, int command, int channel,
int residual_size, int32_t coffset)
{
int pred_order, sum, i, j;
int *coeffs = s->coeffs;
int pred_order, sum, qshift, init_sum, i, j;
const int *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);
if (command == FN_QLPC) {
/* 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++)
s->coeffs[i] = get_sr_golomb_shorten(&s->gb, LPCQUANT);
coeffs = s->coeffs;
qshift = LPCQUANT;
} else {
/* fixed LPC coeffs */
pred_order = command;
coeffs = fixed_coeffs[pred_order-1];
qshift = 0;
}
/* 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)
if (command == FN_QLPC && coffset)
for (i = -pred_order; i < 0; i++)
s->decoded[channel][i] -= coffset;
/* decode residual and do LPC prediction */
init_sum = pred_order ? (command == FN_QLPC ? s->lpcqoffset : 0) : coffset;
for (i=0; i < s->blocksize; i++) {
sum = s->lpcqoffset;
sum = init_sum;
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);
s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + (sum >> qshift);
}
/* add offset to current samples */
if (coffset != 0)
if (command == FN_QLPC && coffset)
for (i = 0; i < s->blocksize; i++)
s->decoded[channel][i] += coffset;
@ -497,34 +514,12 @@ static int shorten_decode_frame(AVCodecContext *avctx,
if (s->version >= 2)
coffset >>= FFMIN(1, s->bitshift);
}
switch (cmd) {
case FN_ZERO:
for (i=0; i<s->blocksize; i++)
s->decoded[channel][i] = 0;
break;
case FN_DIFF0:
for (i=0; i<s->blocksize; i++)
s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + coffset;
break;
case FN_DIFF1:
for (i=0; i<s->blocksize; i++)
s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + s->decoded[channel][i - 1];
break;
case FN_DIFF2:
for (i=0; i<s->blocksize; i++)
s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + 2*s->decoded[channel][i-1]
- s->decoded[channel][i-2];
break;
case FN_DIFF3:
for (i=0; i<s->blocksize; i++)
s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + 3*s->decoded[channel][i-1]
- 3*s->decoded[channel][i-2]
+ s->decoded[channel][i-3];
break;
case FN_QLPC:
if ((ret = decode_subframe_lpc(s, channel, residual_size, coffset)) < 0)
return ret;
break;
if (cmd == FN_ZERO) {
for (i=0; i<s->blocksize; i++)
s->decoded[channel][i] = 0;
} else {
if ((ret = decode_subframe_lpc(s, cmd, channel, residual_size, coffset)) < 0)
return ret;
}
if (s->nmean > 0) {
int32_t sum = (s->version < 2) ? 0 : s->blocksize / 2;