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Code Issues Releases Activity

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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61
libavcodec/shorten.c
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@ -267,12 +267,19 @@ static int16_t * interleave_buffer(int16_t *samples, int nchan, int blocksize, i
return samples; 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 residual_size, int32_t coffset)
{ {
int pred_order, sum, i, j; int pred_order, sum, qshift, init_sum, i, j;
int *coeffs = s->coeffs; const int *coeffs;
if (command == FN_QLPC) {
/* read/validate prediction order */ /* read/validate prediction order */
pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE); pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE);
if (pred_order > s->nwrap) { if (pred_order > s->nwrap) {
@ -281,23 +288,33 @@ static int decode_subframe_lpc(ShortenContext *s, int channel,
} }
/* read LPC coefficients */ /* read LPC coefficients */
for (i=0; i<pred_order; i++) for (i=0; i<pred_order; i++)
coeffs[i] = get_sr_golomb_shorten(&s->gb, LPCQUANT); 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;
}
/* subtract offset from previous samples to use in prediction */ /* subtract offset from previous samples to use in prediction */
if (coffset) if (command == FN_QLPC && coffset)
for (i = -pred_order; i < 0; i++) for (i = -pred_order; i < 0; i++)
s->decoded[channel][i] -= coffset; s->decoded[channel][i] -= coffset;
/* decode residual and do LPC prediction */ /* decode residual and do LPC prediction */
init_sum = pred_order ? (command == FN_QLPC ? s->lpcqoffset : 0) : coffset;
for (i=0; i < s->blocksize; i++) { for (i=0; i < s->blocksize; i++) {
sum = s->lpcqoffset; sum = init_sum;
for (j=0; j<pred_order; j++) for (j=0; j<pred_order; j++)
sum += coeffs[j] * s->decoded[channel][i-j-1]; 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 */ /* add offset to current samples */
if (coffset != 0) if (command == FN_QLPC && coffset)
for (i = 0; i < s->blocksize; i++) for (i = 0; i < s->blocksize; i++)
s->decoded[channel][i] += coffset; s->decoded[channel][i] += coffset;
@ -497,34 +514,12 @@ static int shorten_decode_frame(AVCodecContext *avctx,
if (s->version >= 2) if (s->version >= 2)
coffset >>= FFMIN(1, s->bitshift); coffset >>= FFMIN(1, s->bitshift);
} }
switch (cmd) { if (cmd == FN_ZERO) {
case FN_ZERO:
for (i=0; i<s->blocksize; i++) for (i=0; i<s->blocksize; i++)
s->decoded[channel][i] = 0; s->decoded[channel][i] = 0;
break; } else {
case FN_DIFF0: if ((ret = decode_subframe_lpc(s, cmd, channel, residual_size, coffset)) < 0)
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; return ret;
break;
} }
if (s->nmean > 0) { if (s->nmean > 0) {
int32_t sum = (s->version < 2) ? 0 : s->blocksize / 2; int32_t sum = (s->version < 2) ? 0 : s->blocksize / 2;