[FFmpeg-devel] [PATCH] avfilter/af_tremolo: make it bit-exact with sox effect of same name

[Kyle Swanson]

Sorry, I meant to type (1.0 / s->freq). This is one wavelength.

On Thu, Sep 24, 2015 at 9:29 AM, Kyle Swanson <k at ylo.ph> wrote:
>>  s->table = av_malloc_array(inlink->sample_rate, sizeof(*s->table));
>
>
> Just wondering. Is there a reason that the size of s->table is
> (inlink->sample_rate)  and not (1.0 / inlink->sample_rate) ?
>
> Thanks!
> Kyle
>
> On Wed, Sep 23, 2015 at 6:16 PM, Kyle Swanson <k at ylo.ph> wrote:
>> Looks good. Thanks for the clean-up.
>>
>> On Wed, Sep 23, 2015 at 4:22 PM, Paul B Mahol <onemda at gmail.com> wrote:
>>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>>> ---
>>>  libavfilter/Makefile     |  2 +-
>>>  libavfilter/af_tremolo.c | 45 ++++++++++++++++++++++-----------------------
>>>  2 files changed, 23 insertions(+), 24 deletions(-)
>>>
>>> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
>>> index 7054275..c70887e 100644
>>> --- a/libavfilter/Makefile
>>> +++ b/libavfilter/Makefile
>>> @@ -85,7 +85,7 @@ OBJS-$(CONFIG_SILENCEREMOVE_FILTER)          += af_silenceremove.o
>>>  OBJS-$(CONFIG_STEREOTOOLS_FILTER)            += af_stereotools.o
>>>  OBJS-$(CONFIG_STEREOWIDEN_FILTER)            += af_stereowiden.o
>>>  OBJS-$(CONFIG_TREBLE_FILTER)                 += af_biquads.o
>>> -OBJS-$(CONFIG_TREMOLO_FILTER)                += af_tremolo.o generate_wave_table.o
>>> +OBJS-$(CONFIG_TREMOLO_FILTER)                += af_tremolo.o
>>>  OBJS-$(CONFIG_VOLUME_FILTER)                 += af_volume.o
>>>  OBJS-$(CONFIG_VOLUMEDETECT_FILTER)           += af_volumedetect.o
>>>
>>> diff --git a/libavfilter/af_tremolo.c b/libavfilter/af_tremolo.c
>>> index 6335401..0ae7a7c 100644
>>> --- a/libavfilter/af_tremolo.c
>>> +++ b/libavfilter/af_tremolo.c
>>> @@ -22,15 +22,13 @@
>>>  #include "avfilter.h"
>>>  #include "internal.h"
>>>  #include "audio.h"
>>> -#include "generate_wave_table.h"
>>>
>>>  typedef struct TremoloContext {
>>>      const AVClass *class;
>>>      double freq;
>>>      double depth;
>>> -    double *wave_table;
>>> -    int wave_table_index;
>>> -    int sample_rate;
>>> +    double *table;
>>> +    int index;
>>>  } TremoloContext;
>>>
>>>  #define OFFSET(x) offsetof(TremoloContext, x)
>>> @@ -44,20 +42,11 @@ static const AVOption tremolo_options[] = {
>>>
>>>  AVFILTER_DEFINE_CLASS(tremolo);
>>>
>>> -static double trem_env(AVFilterContext *ctx)
>>> -{
>>> -    TremoloContext *s = ctx->priv;
>>> -    double env = s->wave_table[s->wave_table_index];
>>> -    s->wave_table_index++;
>>> -    if (s->wave_table_index >= s->sample_rate / s->freq)
>>> -        s->wave_table_index = 0;
>>> -    return 1.0 - (s->depth * env);
>>> -}
>>> -
>>>  static int filter_frame(AVFilterLink *inlink, AVFrame *in)
>>>  {
>>>      AVFilterContext *ctx = inlink->dst;
>>>      AVFilterLink *outlink = ctx->outputs[0];
>>> +    TremoloContext *s = ctx->priv;
>>>      const double *src = (const double *)in->data[0];
>>>      const int channels = inlink->channels;
>>>      const int nb_samples = in->nb_samples;
>>> @@ -78,12 +67,13 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
>>>      dst = (double *)out->data[0];
>>>
>>>      for (n = 0; n < nb_samples; n++) {
>>> -        const double env = trem_env(ctx);
>>> -
>>>          for (c = 0; c < channels; c++)
>>> -            dst[c] = src[c] * env;
>>> +            dst[c] = src[c] * s->table[s->index];
>>>          dst += channels;
>>>          src += channels;
>>> +        s->index++;
>>> +        if (s->index >= inlink->sample_rate)
>>> +            s->index = 0;
>>>      }
>>>
>>>      if (in != out)
>>> @@ -125,21 +115,30 @@ static int query_formats(AVFilterContext *ctx)
>>>  static av_cold void uninit(AVFilterContext *ctx)
>>>  {
>>>      TremoloContext *s = ctx->priv;
>>> -    av_freep(&s->wave_table);
>>> +    av_freep(&s->table);
>>>  }
>>>
>>>  static int config_input(AVFilterLink *inlink)
>>>  {
>>>      AVFilterContext *ctx = inlink->dst;
>>>      TremoloContext *s = ctx->priv;
>>> +    const double offset = 1. - s->depth / 2.;
>>> +    int i;
>>>
>>> -    s->sample_rate = inlink->sample_rate;
>>> -    s->wave_table = av_malloc_array(s->sample_rate / s->freq, sizeof(*s->wave_table));
>>> -    if (!s->wave_table)
>>> +    s->table = av_malloc_array(inlink->sample_rate, sizeof(*s->table));
>>> +    if (!s->table)
>>>          return AVERROR(ENOMEM);
>>>
>>> -    ff_generate_wave_table(WAVE_SIN, AV_SAMPLE_FMT_DBL, s->wave_table, s->sample_rate / s->freq, 0.0, 1.0, 0.0);
>>> -    s->wave_table_index = 0;
>>> +    for (i = 0; i < inlink->sample_rate; i++) {
>>> +        double env = s->freq * i / inlink->sample_rate;
>>> +
>>> +        env = sin(2 * M_PI * fmod(env + 0.25, 1.0));
>>> +
>>> +        s->table[i] = env * (1 - fabs(offset)) + offset;
>>> +    }
>>> +
>>> +    s->index = 0;
>>> +
>>>      return 0;
>>>  }
>>>
>>> --
>>> 1.9.1
>>>
>>> _______________________________________________
>>> ffmpeg-devel mailing list
>>> ffmpeg-devel at ffmpeg.org
>>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel