On 4/27/2016 2:22 PM, foo86 wrote:
> ---
> Changelog | 1 +
> libavcodec/Makefile | 2 +-
> libavcodec/dca_lbr.c | 1858
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> libavcodec/dca_lbr.h | 130 ++++
> libavcodec/dcadata.c | 460 +++++++++++++
> libavcodec/dcadata.h | 46 ++
> libavcodec/dcadec.c | 22 +-
> libavcodec/dcadec.h | 5 +-
> libavcodec/dcadsp.c | 27 +
> libavcodec/dcadsp.h | 4 +
> libavcodec/dcahuff.c | 245 ++++++-
> libavcodec/dcahuff.h | 13 +
> 12 files changed, 2807 insertions(+), 6 deletions(-)
> create mode 100644 libavcodec/dca_lbr.c
> create mode 100644 libavcodec/dca_lbr.h
[...]
> +#define SW0 0.022810893
> +#define SW1 0.41799772
> +#define SW2 0.9084481
> +#define SW3 0.99973983
> +
> +#define C1 0.068974845
> +#define C2 0.34675997
> +#define C3 0.29396889
> +#define C4 0.19642374
> +
> +#define AL1 0.30865827
> +#define AL2 0.038060233
Make sure these are float. gcc, clang and icc are all converting the
time_samples
below to double before multiplying, making the following function much slower
than it should be.
> +
> +static void transform_channel(DCALbrDecoder *s, int ch, float *output)
> +{
> + LOCAL_ALIGNED(32, float, values, [DCA_LBR_SUBBANDS ], [4]);
> + LOCAL_ALIGNED(32, float, result, [DCA_LBR_SUBBANDS * 2], [4]);
LOCAL_ALIGNED_32(float, ...)
> + int i, sf, nsubbands = s->nsubbands, noutsubbands = 8 << s->freq_range;
> +
> + // Clear inactive subbands
> + if (nsubbands < noutsubbands)
> + memset(values[nsubbands], 0, (noutsubbands - nsubbands) *
> sizeof(values[0]));
> +
> + for (sf = 0; sf < DCA_LBR_TIME_SAMPLES / 4; sf++) {
> + // Short window and 8 point forward MDCT
According to perf, a lot of CPU time is spent on this and the aliasing
cancellation
code below, at least with a mono sample i found in the wild. Fixing the
constants
above helps a lot, though.
It looks like it shouldn't be hard to write using simd, so maybe it would be a
good
idea to move this part to dcadsp.
> + for (i = 0; i < nsubbands; i++) {
> + float *samples = &s->time_samples[ch][i][sf * 4];
> +
> + float a = samples[-4] * SW0 - samples[-1] * SW3;
> + float b = samples[-3] * SW1 - samples[-2] * SW2;
> + float c = samples[ 2] * SW1 + samples[ 1] * SW2;
> + float d = samples[ 3] * SW0 + samples[ 0] * SW3;
> +
> + values[i][0] = C1 * b - C2 * c + C4 * a - C3 * d;
> + values[i][1] = C1 * d - C2 * a - C4 * b - C3 * c;
> + values[i][2] = C3 * b + C2 * d - C4 * c + C1 * a;
> + values[i][3] = C3 * a - C2 * b + C4 * d - C1 * c;
> + }
> +
> + // Aliasing cancellation for high frequencies
> + for (i = 12; i < nsubbands - 1; i++) {
> + float a = values[i ][3] * AL1;
> + float b = values[i+1][0] * AL1;
> + values[i ][3] += b - a;
> + values[i+1][0] -= b + a;
> + a = values[i ][2] * AL2;
> + b = values[i+1][1] * AL2;
> + values[i ][2] += b - a;
> + values[i+1][1] -= b + a;
> + }
> +
> + base_func_synth(s, ch, values[0], sf);
> +
> + s->imdct.imdct_calc(&s->imdct, result[0], values[0]);
> +
> + // Long window and overlap-add
> + s->fdsp->vector_fmul_add(output, result[0], s->window,
> + s->history[ch], noutsubbands * 4);
> + s->fdsp->vector_fmul_reverse(s->history[ch], result[noutsubbands],
> + s->window, noutsubbands * 4);
> + output += noutsubbands * 4;
> + }
> +
> + // Update history for LPC and forward MDCT
> + for (i = 0; i < nsubbands; i++) {
> + float *samples = s->time_samples[ch][i] - DCA_LBR_TIME_HISTORY;
> + memcpy(samples, samples + DCA_LBR_TIME_SAMPLES, DCA_LBR_TIME_HISTORY
> * sizeof(float));
> + }
> +}
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
