[FFmpeg-devel,GSOC] avfilter: add fluidsynth filter

This patch is part of the qualification task for Audio Tones Source Filter.
---
 Changelog                     |   1 +
 configure                     |   4 +
 doc/filters.texi              |  26 +++++
 libavfilter/Makefile          |   1 +
 libavfilter/allfilters.c      |   1 +
 libavfilter/asrc_fluidsynth.c | 177 ++++++++++++++++++++++++++++++++++
 libavfilter/version.h         |   2 +-
 7 files changed, 211 insertions(+), 1 deletion(-)
 create mode 100644 libavfilter/asrc_fluidsynth.c

On 3/12/20, Marshall Murmu <marshallmax1991@gmail.com> wrote:
> This patch is part of the qualification task for Audio Tones Source Filter.
> ---
>  Changelog                     |   1 +
>  configure                     |   4 +
>  doc/filters.texi              |  26 +++++
>  libavfilter/Makefile          |   1 +
>  libavfilter/allfilters.c      |   1 +
>  libavfilter/asrc_fluidsynth.c | 177 ++++++++++++++++++++++++++++++++++

Name of filter is asrc_atone.c

>  libavfilter/version.h         |   2 +-
>  7 files changed, 211 insertions(+), 1 deletion(-)
>  create mode 100644 libavfilter/asrc_fluidsynth.c
>
> diff --git a/Changelog b/Changelog
> index db2ca92e8a..2a22599969 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -46,6 +46,7 @@ version <next>:
>  - High Voltage Software ADPCM decoder
>  - LEGO Racers ALP (.tun & .pcm) demuxer
>  - AMQP 0-9-1 protocol (RabbitMQ)
> +- fluidsynth filter
>
>
>  version 4.2:
> diff --git a/configure b/configure
> index 8b17134944..b22a09fac1 100755
> --- a/configure
> +++ b/configure
> @@ -233,6 +233,7 @@ External library support:
>                             and libraw1394 [no]
>    --enable-libfdk-aac      enable AAC de/encoding via libfdk-aac [no]
>    --enable-libflite        enable flite (voice synthesis) support via
> libflite [no]
> +  --enable-libfluidsynth   enable fluidsynth support via libfluidsynth [no]
>    --enable-libfontconfig   enable libfontconfig, useful for drawtext filter
> [no]
>    --enable-libfreetype     enable libfreetype, needed for drawtext filter
> [no]
>    --enable-libfribidi      enable libfribidi, improves drawtext filter [no]
> @@ -1770,6 +1771,7 @@ EXTERNAL_LIBRARY_LIST="
>      libdc1394
>      libdrm
>      libflite
> +    libfluidsynth
>      libfontconfig
>      libfreetype
>      libfribidi
> @@ -3509,6 +3511,7 @@ find_rect_filter_deps="avcodec avformat gpl"
>  firequalizer_filter_deps="avcodec"
>  firequalizer_filter_select="rdft"
>  flite_filter_deps="libflite"
> +fluidsynth_filter_deps="libfluidsynth"
>  framerate_filter_select="scene_sad"
>  freezedetect_filter_select="scene_sad"
>  frei0r_filter_deps="frei0r libdl"
> @@ -6269,6 +6272,7 @@ enabled libfdk_aac        && { check_pkg_config
> libfdk_aac fdk-aac "fdk-aac/aace
>                                   warn "using libfdk without pkg-config"; }
> }
>  flite_extralibs="-lflite_cmu_time_awb -lflite_cmu_us_awb -lflite_cmu_us_kal
> -lflite_cmu_us_kal16 -lflite_cmu_us_rms -lflite_cmu_us_slt -lflite_usenglish
> -lflite_cmulex -lflite"
>  enabled libflite          && require libflite "flite/flite.h" flite_init
> $flite_extralibs
> +enabled libfluidsynth     && require_pkg_config libfluidsynth fluidsynth
> "fluidsynth.h" fluid_log
>  enabled fontconfig        && enable libfontconfig
>  enabled libfontconfig     && require_pkg_config libfontconfig fontconfig
> "fontconfig/fontconfig.h" FcInit
>  enabled libfreetype       && require_pkg_config libfreetype freetype2
> "ft2build.h FT_FREETYPE_H" FT_Init_FreeType
> diff --git a/doc/filters.texi b/doc/filters.texi
> index ff008b119f..cdf96d1ba1 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -6010,6 +6010,32 @@ ffplay -f lavfi flite=text='No more be grieved for
> which that thou hast done.'
>  For more information about libflite, check:
>  @url{http://www.festvox.org/flite/}
>
> +@section fluidsynth
> +
> +Synthesize random notes using libfluidsynth library.
> +
> +To compile this filter you need to configure FFmpeg with
> +@code{--enable-libfluidsynth}.
> +
> +The filter accepts the following options:
> +
> +@table @option
> +@item sample_rate, r
> +Set the sample rate of the synthesizer. Default value is 44100.
> +
> +@item nb_samples, n
> +Set the number of samples per frame. Default value is 1024.
> +
> +@item duration, d
> +Set the duration of sound generation. Default value is 10 sec.
> +
> +@item soundfont
> +Enter the location of the soundfont. Without loading the soundfont
> fluidsynth won't be able to synthesize.
> +
> +@item chan
> +Set the MIDI channel. Default value is 0.
> +@end table
> +
>  @section anoisesrc
>
>  Generate a noise audio signal.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 750412da6b..626d7c0f09 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -148,6 +148,7 @@ OBJS-$(CONFIG_AFIRSRC_FILTER)                +=
> asrc_afirsrc.o
>  OBJS-$(CONFIG_ANOISESRC_FILTER)              += asrc_anoisesrc.o
>  OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
>  OBJS-$(CONFIG_FLITE_FILTER)                  += asrc_flite.o
> +OBJS-$(CONFIG_FLUIDSYNTH_FILTER)             += asrc_fluidsynth.o
>  OBJS-$(CONFIG_HILBERT_FILTER)                += asrc_hilbert.o
>  OBJS-$(CONFIG_SINC_FILTER)                   += asrc_sinc.o
>  OBJS-$(CONFIG_SINE_FILTER)                   += asrc_sine.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 501e5d041b..a1e812093c 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -142,6 +142,7 @@ extern AVFilter ff_asrc_afirsrc;
>  extern AVFilter ff_asrc_anoisesrc;
>  extern AVFilter ff_asrc_anullsrc;
>  extern AVFilter ff_asrc_flite;
> +extern AVFilter ff_asrc_fluidsynth;
>  extern AVFilter ff_asrc_hilbert;
>  extern AVFilter ff_asrc_sinc;
>  extern AVFilter ff_asrc_sine;
> diff --git a/libavfilter/asrc_fluidsynth.c b/libavfilter/asrc_fluidsynth.c
> new file mode 100644
> index 0000000000..be98815c56
> --- /dev/null
> +++ b/libavfilter/asrc_fluidsynth.c
> @@ -0,0 +1,177 @@
> +/*
> + * 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
> + */
> +
> +#include <fluidsynth.h>
> +#include "libavutil/avassert.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/lfg.h"
> +#include "libavutil/random_seed.h"
> +#include "avfilter.h"
> +#include "audio.h"
> +#include "formats.h"
> +#include "internal.h"
> +
> +typedef struct FluidSynthContext {
> +    const AVClass *class;
> +    fluid_settings_t *settings;
> +    fluid_synth_t *synth;
> +    int soundfont_id;
> +    int nb_samples;
> +    int sample_rate;
> +    int chan;
> +    char *soundfont;
> +    int64_t pts;
> +    int64_t duration;
> +    AVLFG c;
> +} FluidSynthContext;
> +
> +#define OFFSET(x) offsetof(FluidSynthContext, x)
> +#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
> +
> +static const AVOption fluidsynth_options[] = {
> +    {"sample_rate", "set sample rate",
> OFFSET(sample_rate), AV_OPT_TYPE_INT,      {.i64=44100},    1,
> INT_MAX,   FLAGS},
> +    {"r",           "set sample rate",
> OFFSET(sample_rate), AV_OPT_TYPE_INT,      {.i64=44100},    1,
> INT_MAX,   FLAGS},
> +    {"nb_samples",  "set number of samples per requested frame",
> OFFSET(nb_samples),  AV_OPT_TYPE_INT,      {.i64=1024},     1,
> INT64_MAX, FLAGS},
> +    {"n",           "set number of samples per requested frame",
> OFFSET(nb_samples),  AV_OPT_TYPE_INT,      {.i64=1024},     1,
> INT64_MAX, FLAGS},
> +    {"duration",    "set duration",
> OFFSET(duration),    AV_OPT_TYPE_DURATION, {.i64=10000000}, 0,
> INT64_MAX, FLAGS},
> +    {"d",           "set duration",
> OFFSET(duration),    AV_OPT_TYPE_DURATION, {.i64=10000000}, 0,
> INT64_MAX, FLAGS},
> +    {"soundfont",   "location of soundfont",
> OFFSET(soundfont),   AV_OPT_TYPE_STRING,   {.str=NULL},     CHAR_MIN,
> CHAR_MAX,  FLAGS},
> +    {"chan",        "set MIDI channel",
> OFFSET(chan),        AV_OPT_TYPE_INT,      {.str=0},        0,        15,
>     FLAGS},
> +    { NULL }
> +};
> +
> +AVFILTER_DEFINE_CLASS(fluidsynth);
> +
> +static av_cold int init(AVFilterContext *ctx)
> +{
> +    FluidSynthContext *fluidsynth = ctx->priv;
> +    fluidsynth->soundfont_id = -1;
> +    /// Initialize the fluidsynth setting
> +    fluidsynth->settings = new_fluid_settings();
> +    if(fluidsynth->settings == NULL) {
> +        av_log(ctx, AV_LOG_ERROR, "Failed to create fluidsynth
> settings\n");
> +        return AVERROR_UNKNOWN;
> +    }
> +    /// Initialize the synthesizer
> +    fluidsynth->synth = new_fluid_synth(fluidsynth->settings);
> +    if(fluidsynth->synth == NULL) {
> +        av_log(ctx, AV_LOG_ERROR, "Failed to create fluidsynth
> synthesizer\n");
> +        return AVERROR_UNKNOWN;
> +    }
> +
> +    fluidsynth->soundfont_id = fluid_synth_sfload(fluidsynth->synth,
> fluidsynth->soundfont, 1);
> +    if(fluidsynth->soundfont_id < 0) {
> +        av_log(ctx, AV_LOG_ERROR, "Failed to load soundfont\n");
> +    }
> +
> +    return 0;
> +}
> +
> +static av_cold void uninit(AVFilterContext *ctx)
> +{
> +    FluidSynthContext *fluidsynth = ctx->priv;
> +
> +    delete_fluid_synth(fluidsynth->synth);
> +    delete_fluid_settings(fluidsynth->settings);
> +

Remove excessive new line.

> +}
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> +    FluidSynthContext *fluidsynth = ctx->priv;
> +
> +    AVFilterChannelLayouts *chanlayout = NULL;
> +    int64_t chanlayouts =
> av_get_default_channel_layout(2*fluid_synth_count_audio_channels(fluidsynth->synth));
> +

Why this have multiplication by 2?

> +    AVFilterFormats *formats = NULL;
> +    AVFilterFormats *sample_rate = NULL;
> +    int ret;
> +
> +    if ((ret = ff_add_format                 (&formats    ,
> AV_SAMPLE_FMT_FLT      )) < 0 ||
> +        (ret = ff_set_common_formats         (ctx         , formats
>        )) < 0 ||
> +        (ret = ff_add_channel_layout         (&chanlayout , chanlayouts
>        )) < 0 ||
> +        (ret = ff_set_common_channel_layouts (ctx         , chanlayout
>        )) < 0 ||
> +        (ret = ff_add_format                 (&sample_rate,
> fluidsynth->sample_rate)) < 0 ||
> +        (ret = ff_set_common_samplerates     (ctx         , sample_rate
>        )) < 0)
> +        return ret;
> +    return 0;
> +}
> +
> +
> +static int config_output(AVFilterLink *outlink)
> +{
> +    AVFilterContext *ctx = outlink->src;
> +    FluidSynthContext *fluidsynth = ctx->priv;
> +
> +    av_lfg_init(&fluidsynth->c, av_get_random_seed());

Seed should be an option like in other filters.

> +
> +    outlink->sample_rate = fluidsynth->sample_rate;
> +    fluidsynth->duration = av_rescale(fluidsynth->duration,
> fluidsynth->sample_rate, AV_TIME_BASE);
> +
> +    return 0;
> +}
> +
> +static int request_frame(AVFilterLink *outlink)
> +{
> +    AVFrame *frame;
> +    FluidSynthContext *fluidsynth = outlink->src->priv;
> +    int nb_samples, key;
> +
> +    if (fluidsynth->duration) {
> +        nb_samples = FFMIN(fluidsynth->nb_samples, fluidsynth->duration -
> fluidsynth->pts);
> +        av_assert1(nb_samples >= 0);
> +        if (!nb_samples)
> +            return AVERROR_EOF;
> +    }
> +
> +    if(!(frame = ff_get_audio_buffer(outlink, nb_samples)))
> +        return AVERROR(ENOMEM);
> +
> +    key = av_lfg_get(&fluidsynth->c) % 128 ;
> +
> +    fluid_synth_noteon(fluidsynth->synth, fluidsynth->chan, key, 100);
> +    fluid_synth_write_float(fluidsynth->synth, nb_samples, frame->data[0],
> 0, 2, frame->data[0], 1, 2);
> +    fluid_synth_noteoff(fluidsynth->synth, fluidsynth->chan, key);
> +
> +    frame->pts = fluidsynth->pts;
> +    fluidsynth->pts += nb_samples;
> +
> +    return ff_filter_frame(outlink, frame);
> +}
> +
> +static const AVFilterPad fluidsynth_outputs[] = {
> +    {
> +        .name          = "default",
> +        .type          = AVMEDIA_TYPE_AUDIO,
> +        .request_frame = request_frame,
> +        .config_props  = config_output,
> +    },
> +    { NULL }
> +};
> +
> +AVFilter ff_asrc_fluidsynth = {
> +    .name          = "fluidsynth",

Name should be atone.

> +    .description   = NULL_IF_CONFIG_SMALL("Synthesize tones using
> libfluidsynth."),
> +    .query_formats = query_formats,
> +    .init          = init,
> +    .uninit        = uninit,
> +    .priv_size     = sizeof(FluidSynthContext),
> +    .inputs        = NULL,
> +    .outputs       = fluidsynth_outputs,
> +    .priv_class    = &fluidsynth_class,
> +};
> diff --git a/libavfilter/version.h b/libavfilter/version.h
> index 7b41018be7..4c4e8afe2d 100644
> --- a/libavfilter/version.h
> +++ b/libavfilter/version.h
> @@ -30,7 +30,7 @@
>  #include "libavutil/version.h"
>
>  #define LIBAVFILTER_VERSION_MAJOR   7
> -#define LIBAVFILTER_VERSION_MINOR  77
> +#define LIBAVFILTER_VERSION_MINOR  78
>  #define LIBAVFILTER_VERSION_MICRO 100
>
>
> --
> 2.25.0
>
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>
> > +}
>> > +
>> > +static int query_formats(AVFilterContext *ctx)
>> > +{
>> > +    FluidSynthContext *fluidsynth = ctx->priv;
>> > +
>> > +    AVFilterChannelLayouts *chanlayout = NULL;
>> > +    int64_t chanlayouts =
>> >
>> av_get_default_channel_layout(2*fluid_synth_count_audio_channels(fluidsynth->synth));
>> > +
>> Why this have multiplication by 2?
>
> Because the function actually returns the number of stereo pairs. Hence
> 1=2 channels, 2=4 and so on.