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x86/tx_float: generalize iMDCT

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To support non-aligned buffers during the post-transform step, just iterate
backwards over the array.

This allows using the 15xN-point FFT, with which the speed is 2.1 times
faster than our old libavcodec implementation.
This commit is contained in:
Lynne
2022-09-23 10:38:29 +02:00
parent ace42cf581
commit 74e8541bab
2 changed files with 40 additions and 29 deletions
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17
libavutil/x86/tx_float_init.c
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@@ -46,7 +46,7 @@ TX_DECL_FN(fft_sr_ns, avx2)
TX_DECL_FN(fft_pfa_15xM, avx2)
TX_DECL_FN(fft_pfa_15xM_ns, avx2)
TX_DECL_FN(mdct_sr_inv, avx2)
TX_DECL_FN(mdct_inv, avx2)
TX_DECL_FN(fft2_asm, sse3)
TX_DECL_FN(fft4_fwd_asm, sse2)
@@ -87,7 +87,7 @@ static av_cold int m_inv_init(AVTXContext *s, const FFTXCodelet *cd,
int len, int inv, const void *scale)
{
int ret;
FFTXCodeletOptions sub_opts = { .invert_lookup = -1 };
FFTXCodeletOptions sub_opts = { .invert_lookup = 1 };
s->scale_d = *((SCALE_TYPE *)scale);
s->scale_f = s->scale_d;
@@ -101,7 +101,16 @@ static av_cold int m_inv_init(AVTXContext *s, const FFTXCodelet *cd,
inv, scale)))
return ret;
if ((ret = ff_tx_mdct_gen_exp_float(s, s->sub->map)))
s->map = av_malloc(len*sizeof(*s->map));
if (!s->map)
return AVERROR(ENOMEM);
memcpy(s->map, s->sub->map, (len >> 1)*sizeof(*s->map));
/* Invert lookup table for unstrided path */
for (int i = 0; i < (len >> 1); i++)
s->map[(len >> 1) + s->map[i]] = i;
if ((ret = ff_tx_mdct_gen_exp_float(s, s->map)))
return ret;
return 0;
@@ -226,7 +235,7 @@ const FFTXCodelet * const ff_tx_codelet_list_float_x86[] = {
TX_DEF(fft_pfa_15xM_ns, FFT, 60, TX_LEN_UNLIMITED, 15, TX_FACTOR_ANY, 384, fft_pfa_init, avx2, AVX2,
AV_TX_INPLACE | FF_TX_PRESHUFFLE, AV_CPU_FLAG_AVXSLOW | AV_CPU_FLAG_SLOW_GATHER),
TX_DEF(mdct_sr_inv, MDCT, 16, TX_LEN_UNLIMITED, 2, TX_FACTOR_ANY, 384, m_inv_init, avx2, AVX2,
TX_DEF(mdct_inv, MDCT, 16, TX_LEN_UNLIMITED, 2, TX_FACTOR_ANY, 384, m_inv_init, avx2, AVX2,
FF_TX_INVERSE_ONLY, AV_CPU_FLAG_AVXSLOW | AV_CPU_FLAG_SLOW_GATHER),
#endif
#endif