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avcodec/dsd: Hoist branch out of loop

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This is possible by not converting from LSBF to MSBF; instead
add LSBF LUTs.
This approach necessitates reversing the initial values.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2024-04-01 00:03:09 +02:00
parent 6d38c260e5
commit aecd63478e
2 changed files with 10 additions and 5 deletions
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12
libavcodec/dsd.c
View file

@ -68,7 +68,8 @@ static const double htaps[HTAPS] = {
3.423230509967409e-07, 1.244182214744588e-07, 3.130441005359396e-08
};
static double ctables[CTABLES][256];
static double ctables_lsbf[CTABLES][256];
static double ctables_msbf[CTABLES][256];
static av_cold void dsd_ctables_tableinit(void)
{
@ -81,8 +82,10 @@ static av_cold void dsd_ctables_tableinit(void)
for (t = 0; t < CTABLES; ++t)
acc[t] += sign * htaps[t * 8 + m];
}
for (t = 0; t < CTABLES; ++t)
ctables[CTABLES - 1 - t][e] = acc[t];
for (t = 0; t < CTABLES; ++t) {
ctables_msbf[CTABLES - 1 - t][e] = acc[t];
ctables_lsbf[CTABLES - 1 - t][ff_reverse[e]] = acc[t];
}
}
}
@ -100,13 +103,14 @@ void ff_dsd2pcm_translate(DSDContext* s, size_t samples, int lsbf,
unsigned pos, i;
uint8_t* p;
double sum;
const double (*const ctables)[256] = lsbf ? ctables_lsbf : ctables_msbf;
pos = s->pos;
memcpy(buf, s->buf, sizeof(buf));
while (samples-- > 0) {
buf[pos] = lsbf ? ff_reverse[*src] : *src;
buf[pos] = *src;
src += src_stride;
p = buf + ((pos - CTABLES) & FIFOMASK);

3
libavcodec/dsddec.c
View file

@ -56,7 +56,8 @@ static av_cold int decode_init(AVCodecContext *avctx)
if (!s)
return AVERROR(ENOMEM);
silence = DSD_SILENCE;
silence = avctx->codec_id == AV_CODEC_ID_DSD_LSBF_PLANAR ||
avctx->codec_id == AV_CODEC_ID_DSD_LSBF ? DSD_SILENCE_REVERSED : DSD_SILENCE;
for (i = 0; i < avctx->ch_layout.nb_channels; i++) {
s[i].pos = 0;
memset(s[i].buf, silence, sizeof(s[i].buf));