[FFmpeg-devel] [PATCH] avfilter: add tremolo filter

Kyle Swanson k at ylo.ph
Mon Sep 21 17:21:25 CEST 2015


I've made these changes and have re-submitted as a new patch. Thanks!

On Sun, Sep 20, 2015 at 2:46 AM, Paul B Mahol <onemda at gmail.com> wrote:
> Dana 20. 9. 2015. 06:28 osoba "Kyle Swanson" <k at ylo.ph> napisala je:
>>
>> Signed-off-by: Kyle Swanson <k at ylo.ph>
>> ---
>>  doc/filters.texi         |  19 ++++++
>>  libavfilter/Makefile     |   1 +
>>  libavfilter/af_tremolo.c | 173
> +++++++++++++++++++++++++++++++++++++++++++++++
>>  libavfilter/allfilters.c |   1 +
>>  libavfilter/version.h    |   2 +-
>>  5 files changed, 195 insertions(+), 1 deletion(-)
>>  create mode 100644 libavfilter/af_tremolo.c
>>
>> diff --git a/doc/filters.texi b/doc/filters.texi
>> index 88cb3ce..5bbbaf0 100644
>> --- a/doc/filters.texi
>> +++ b/doc/filters.texi
>> @@ -2568,6 +2568,25 @@ slope
>>  Determine how steep is the filter's shelf transition.
>>  @end table
>>
>> + at section tremolo
>> +
>> +Sinusoidal amplitude modulation.
>> +
>> +The filter accepts the following options:
>> +
>> + at table @option
>> + at item f
>> +Modulation frequency in Hertz. Modulation frequencies in the subharmonic
> range
>> +(20 Hz or lower) will result in a tremolo effect.
>> +This filter may also be used as a ring modulator by specifying
>> +a modulation frequency higher than 20 Hz.
>> +Range is 0.1 - 20000.0. Default value is 5.0 Hz.
>> +
>> + at item d
>> +Depth of modulation as a percentage. Range is 0.0 - 1.0.
>> +Default value is 0.5.
>> + at end table
>> +
>>  @section volume
>>
>>  Adjust the input audio volume.
>> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
>> index 05effd6..45fca3b 100644
>> --- a/libavfilter/Makefile
>> +++ b/libavfilter/Makefile
>> @@ -82,6 +82,7 @@ OBJS-$(CONFIG_SILENCEDETECT_FILTER)          +=
> af_silencedetect.o
>>  OBJS-$(CONFIG_SILENCEREMOVE_FILTER)          += af_silenceremove.o
>>  OBJS-$(CONFIG_STEREOTOOLS_FILTER)            += af_stereotools.o
>>  OBJS-$(CONFIG_STEREOWIDEN_FILTER)            += af_stereowiden.o
>> +OBJS-$(CONFIG_TREMOLO_FILTER)                += af_tremolo.o
> generate_wave_table.o
>
> nit: Should be after treble.
>
>>  OBJS-$(CONFIG_TREBLE_FILTER)                 += af_biquads.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
>> new file mode 100644
>> index 0000000..7896127
>> --- /dev/null
>> +++ b/libavfilter/af_tremolo.c
>> @@ -0,0 +1,173 @@
>> +/*
>> + * Tremolo
>> + * Copyright (c) 2015 Kyle Swanson <k at ylo.ph>. Some rights reserved.
>
> What this means? Better remove: Some rights reserved.
>
>> + *
>> + * This file is part of FFmpeg.
>> + *
>> + * FFmpeg is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU Lesser General Public
>> + * License as published by the Free Software Foundation; either
>> + * version 2.1 of the License, or (at your option) any later version.
>> + *
>> + * FFmpeg is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * Lesser General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU Lesser General Public
>> + * License along with FFmpeg; if not, write to the Free Software
>> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
> 02110-1301 USA
>> + */
>> +
>> +/**
>> + * @file
>> + * Tremolo
>> + */
>> +
>> +#include "libavutil/opt.h"
>> +#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;
>> +} TremoloContext;
>> +
>> +#define OFFSET(x) offsetof(TremoloContext, x)
>> +#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
>> +
>> +static const AVOption tremolo_options[] = {
>> +    { "f", "set frequency in hertz",    OFFSET(freq),
> AV_OPT_TYPE_DOUBLE,   {.dbl = 5.0},   0.1,   20000.0, FLAGS },
>> +    { "d", "set depth as percentage",   OFFSET(depth),
>  AV_OPT_TYPE_DOUBLE,   {.dbl = 0.5},   0.0,   1.0,     FLAGS },
>> +    { NULL }
>> +};
>> +
>> +AVFILTER_DEFINE_CLASS(tremolo);
>> +
>> +static float trem_env(AVFilterContext *ctx)
>> +{
>> +    TremoloContext *s = ctx->priv;
>> +    float 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);
>> +}
>
> Shouldnt this use doubles instead of floats?
>
>> +
>> +static int filter_frame(AVFilterLink *inlink, AVFrame *in)
>> +{
>> +    AVFilterContext *ctx = inlink->dst;
>> +    AVFilterLink *outlink = ctx->outputs[0];
>> +    AVFrame *out;
>> +
>> +    if (av_frame_is_writable(in)) {
>> +        out = in;
>> +    } else {
>> +        out = ff_get_audio_buffer(inlink, in->nb_samples);
>> +        if (!out) {
>> +            av_frame_free(&in);
>> +            return AVERROR(ENOMEM);
>> +        }
>> +        av_frame_copy_props(out, in);
>> +    }
>> +
>> +    int channels = inlink->channels;
>> +    int nb_samples = in->nb_samples;
>> +    double *dst = (double *)out->data[0];
>> +    int n, c;
>> +
>> +    for (n = 0; n < nb_samples; n++) {
>> +        float env = trem_env(ctx);
>> +        for (c = 0; c < channels; c++) {
>> +            dst[c] *= env;
>
> Out can be zero if frame is not writable. So use: dst - src * env.
>
>> +        }
>> +        dst += channels;
>> +    }
>> +
>> +    if (in != out)
>> +        av_frame_free(&in);
>> +
>> +    return ff_filter_frame(outlink, out);
>> +}
>> +
>> +static int query_formats(AVFilterContext *ctx)
>> +{
>> +    AVFilterFormats *formats;
>> +    AVFilterChannelLayouts *layouts;
>> +    static const enum AVSampleFormat sample_fmts[] = {
>> +        AV_SAMPLE_FMT_DBL,
>> +        AV_SAMPLE_FMT_NONE
>> +    };
>> +    int ret;
>> +
>> +    layouts = ff_all_channel_counts();
>> +    if (!layouts)
>> +        return AVERROR(ENOMEM);
>> +    ret = ff_set_common_channel_layouts(ctx, layouts);
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    formats = ff_make_format_list(sample_fmts);
>> +    if (!formats)
>> +        return AVERROR(ENOMEM);
>> +    ret = ff_set_common_formats(ctx, formats);
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    formats = ff_all_samplerates();
>> +    if (!formats)
>> +        return AVERROR(ENOMEM);
>> +    return ff_set_common_samplerates(ctx, formats);
>> +}
>> +
>> +static av_cold void uninit(AVFilterContext *ctx)
>> +{
>> +    TremoloContext *s = ctx->priv;
>> +    av_free(s->wave_table);
>> +}
>> +
>> +static int config_input(AVFilterLink *inlink)
>> +{
>> +    AVFilterContext *ctx = inlink->dst;
>> +    TremoloContext *s = ctx->priv;
>> +    s->sample_rate = inlink->sample_rate;
>> +    s->wave_table = av_malloc_array(sizeof(double), s->sample_rate /
> s->freq);
>> +    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;
>> +    return 0;
>> +}
>> +
>> +static const AVFilterPad avfilter_af_tremolo_inputs[] = {
>> +    {
>> +        .name         = "default",
>> +        .type         = AVMEDIA_TYPE_AUDIO,
>> +        .config_props = config_input,
>> +        .filter_frame = filter_frame,
>> +    },
>> +    { NULL }
>> +};
>> +
>> +static const AVFilterPad avfilter_af_tremolo_outputs[] = {
>> +    {
>> +        .name = "default",
>> +        .type = AVMEDIA_TYPE_AUDIO,
>> +    },
>> +    { NULL }
>> +};
>> +
>> +AVFilter ff_af_tremolo = {
>> +    .name          = "tremolo",
>> +    .description   = NULL_IF_CONFIG_SMALL("Audio Tremolo."),
>> +    .priv_size     = sizeof(TremoloContext),
>> +    .priv_class    = &tremolo_class,
>> +    .uninit        = uninit,
>> +    .query_formats = query_formats,
>> +    .inputs        = avfilter_af_tremolo_inputs,
>> +    .outputs       = avfilter_af_tremolo_outputs,
>> +};
>> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
>> index cab4564..59ba5f5 100644
>> --- a/libavfilter/allfilters.c
>> +++ b/libavfilter/allfilters.c
>> @@ -105,6 +105,7 @@ void avfilter_register_all(void)
>>      REGISTER_FILTER(STEREOTOOLS,    stereotools,    af);
>>      REGISTER_FILTER(STEREOWIDEN,    stereowiden,    af);
>>      REGISTER_FILTER(TREBLE,         treble,         af);
>> +    REGISTER_FILTER(TREMOLO,        tremolo,        af);
>>      REGISTER_FILTER(VOLUME,         volume,         af);
>>      REGISTER_FILTER(VOLUMEDETECT,   volumedetect,   af);
>>
>> diff --git a/libavfilter/version.h b/libavfilter/version.h
>> index e918184..9d44fd0 100644
>> --- a/libavfilter/version.h
>> +++ b/libavfilter/version.h
>> @@ -30,7 +30,7 @@
>>  #include "libavutil/version.h"
>>
>>  #define LIBAVFILTER_VERSION_MAJOR   6
>> -#define LIBAVFILTER_VERSION_MINOR   5
>> +#define LIBAVFILTER_VERSION_MINOR   6
>>  #define LIBAVFILTER_VERSION_MICRO 100
>>
>>  #define LIBAVFILTER_VERSION_INT
> AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
>> --
>> 1.8.4
>>
>
> Will do some minor changes, and apply after are questions I raised resolved.
>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel


More information about the ffmpeg-devel mailing list