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

Message ID 20200314102832.31962-1-marshallmax1991@gmail.com
State Superseded
Headers show
Series [FFmpeg-devel,GSOC] avfilter: add atone filter
Related show

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Commit Message

Marshall Murmu March 14, 2020, 10:28 a.m. UTC
Author:    Marshall Murmu <marshallmax1991@gmail.com>


---
 Changelog                |   1 +
 configure                |   4 +
 doc/filters.texi         |  29 +++++++
 libavfilter/Makefile     |   1 +
 libavfilter/allfilters.c |   1 +
 libavfilter/asrc_atone.c | 172 +++++++++++++++++++++++++++++++++++++++
 libavfilter/version.h    |   2 +-
 7 files changed, 209 insertions(+), 1 deletion(-)
 create mode 100644 libavfilter/asrc_atone.c

Comments

Paul B Mahol March 14, 2020, 10:42 a.m. UTC | #1
Please follow coding style from http://ffmpeg.org/developer.html

Otherwise patch looks fine.
Could you make note on/off switching not depend on number of output
samples per frame?

On 3/14/20, Marshall Murmu <marshallmax1991@gmail.com> wrote:
>  Author:    Marshall Murmu <marshallmax1991@gmail.com>
>
>
> ---
>  Changelog                |   1 +
>  configure                |   4 +
>  doc/filters.texi         |  29 +++++++
>  libavfilter/Makefile     |   1 +
>  libavfilter/allfilters.c |   1 +
>  libavfilter/asrc_atone.c | 172 +++++++++++++++++++++++++++++++++++++++
>  libavfilter/version.h    |   2 +-
>  7 files changed, 209 insertions(+), 1 deletion(-)
>  create mode 100644 libavfilter/asrc_atone.c
>
> diff --git a/Changelog b/Changelog
> index d1572553a5..5ddd2484b0 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -48,6 +48,7 @@ version <next>:
>  - AMQP 0-9-1 protocol (RabbitMQ)
>  - Vulkan support
>  - avgblur_vulkan, overlay_vulkan, scale_vulkan and chromaber_vulkan filters
> +- atone filter
>
>
>  version 4.2:
> diff --git a/configure b/configure
> index 6ceb0c7af4..be48a22770 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
> @@ -3465,6 +3467,7 @@ asr_filter_deps="pocketsphinx"
>  ass_filter_deps="libass"
>  atempo_filter_deps="avcodec"
>  atempo_filter_select="rdft"
> +atone_filter_deps="libfluidsynth"
>  avgblur_opencl_filter_deps="opencl"
>  avgblur_vulkan_filter_deps="vulkan libglslang"
>  azmq_filter_deps="libzmq"
> @@ -6270,6 +6273,7 @@ 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
> $flite_extralibs
> +enabled libfluidsynth     && require_pkg_config libfluidsynth fluidsynth
> "fluidsynth.h" fluid_log
>  enabled fontconfig        && enable libfontconfig
>  enabled libfontconfig     && require_pkg_config libfontconfig fontconfig
> "fontconfig/fontconfig.h" FcInit
>  enabled libfreetype       && require_pkg_config libfreetype freetype2
> "ft2build.h FT_FREETYPE_H" FT_Init_FreeType
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 328e984e92..0ef3e83e65 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -5946,6 +5946,35 @@ anullsrc=r=48000:cl=mono
>
>  All the parameters need to be explicitly defined.
>
> +@section atone
> +
> +Synthesize random notes using libfluidsynth library.
> +
> +To compile this filter you need to configure FFmpeg with
> +@code{--enable-libfluidsynth}.
> +
> +The filter accepts the following options:
> +
> +@table @option
> +@item sample_rate, r
> +Set the sample rate of the synthesizer. Default value is 44100.
> +
> +@item nb_samples, n
> +Set the number of samples per frame. Default value is 1024.
> +
> +@item duration, d
> +Set the duration of sound generation. Default value is 10 sec.
> +
> +@item soundfont
> +Enter the location of the soundfont. Without loading the soundfont
> fluidsynth won't be able to synthesize.
> +
> +@item chan
> +Set the MIDI channel. Default value is 0.
> +
> +@item seed
> +Set the seed value for the PRNG
> +@end table
> +
>  @section flite
>
>  Synthesize a voice utterance using the libflite library.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 750412da6b..020c4553cb 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -147,6 +147,7 @@ OBJS-$(CONFIG_AEVALSRC_FILTER)               += aeval.o
>  OBJS-$(CONFIG_AFIRSRC_FILTER)                += asrc_afirsrc.o
>  OBJS-$(CONFIG_ANOISESRC_FILTER)              += asrc_anoisesrc.o
>  OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
> +OBJS-$(CONFIG_ATONE_FILTER)                  += asrc_atone.o
>  OBJS-$(CONFIG_FLITE_FILTER)                  += asrc_flite.o
>  OBJS-$(CONFIG_HILBERT_FILTER)                += asrc_hilbert.o
>  OBJS-$(CONFIG_SINC_FILTER)                   += asrc_sinc.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 501e5d041b..d167499cf1 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -141,6 +141,7 @@ extern AVFilter ff_asrc_aevalsrc;
>  extern AVFilter ff_asrc_afirsrc;
>  extern AVFilter ff_asrc_anoisesrc;
>  extern AVFilter ff_asrc_anullsrc;
> +extern AVFilter ff_asrc_atone;
>  extern AVFilter ff_asrc_flite;
>  extern AVFilter ff_asrc_hilbert;
>  extern AVFilter ff_asrc_sinc;
> diff --git a/libavfilter/asrc_atone.c b/libavfilter/asrc_atone.c
> new file mode 100644
> index 0000000000..f3ebab906e
> --- /dev/null
> +++ b/libavfilter/asrc_atone.c
> @@ -0,0 +1,172 @@
> +/*
> + * 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 AToneContext {
> +    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;
> +    int64_t seed;
> +    AVLFG c;
> +} AToneContext;
> +
> +#define OFFSET(x) offsetof(AToneContext, x)
> +#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
> +
> +static const AVOption atone_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},
> +    {"seed",        "set random seed",
> OFFSET(seed),        AV_OPT_TYPE_INT64,    {.i64=-1},       -1,
> INT64_MAX, FLAGS},
> +    { NULL }
> +};
> +
> +AVFILTER_DEFINE_CLASS(atone);
> +
> +static av_cold int init(AVFilterContext *ctx)
> +{
> +    AToneContext *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)
> +{
> +    AToneContext *fluidsynth = ctx->priv;
> +    delete_fluid_synth(fluidsynth->synth);
> +    delete_fluid_settings(fluidsynth->settings);
> +}
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> +    AToneContext *fluidsynth = ctx->priv;
> +    AVFilterChannelLayouts *chanlayout = NULL;
> +    int64_t chanlayouts =
> av_get_default_channel_layout(2*fluid_synth_count_audio_channels(fluidsynth->synth));
> +    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;
> +    AToneContext *fluidsynth = ctx->priv;
> +
> +    if(fluidsynth->seed == -1)
> +        fluidsynth->seed = av_get_random_seed();
> +    av_lfg_init(&fluidsynth->c, fluidsynth->seed);
> +
> +    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;
> +    AToneContext *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 atone_outputs[] = {
> +    {
> +        .name          = "default",
> +        .type          = AVMEDIA_TYPE_AUDIO,
> +        .request_frame = request_frame,
> +        .config_props  = config_output,
> +    },
> +    { NULL }
> +};
> +
> +AVFilter ff_asrc_atone = {
> +    .name          = "atone",
> +    .description   = NULL_IF_CONFIG_SMALL("Synthesize tones using
> libfluidsynth."),
> +    .query_formats = query_formats,
> +    .init          = init,
> +    .uninit        = uninit,
> +    .priv_size     = sizeof(AToneContext),
> +    .inputs        = NULL,
> +    .outputs       = atone_outputs,
> +    .priv_class    = &atone_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
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
Moritz Barsnick March 16, 2020, 10:10 a.m. UTC | #2
Hi Marshall,

On Sat, Mar 14, 2020 at 15:58:32 +0530, Marshall Murmu wrote:

> +    {"soundfont",   "location of soundfont",                     OFFSET(soundfont),   AV_OPT_TYPE_STRING,   {.str=NULL},     CHAR_MIN, CHAR_MAX,  FLAGS},

I don't think we define ranges for AV_OPT_TYPE_STRING.

> +    if(fluidsynth->settings == NULL) {

As Paul mentioned, whitespace style (throughout the complete source).

Also, "if (!fluidsynth->settings)" is the preferred style.

> +        av_log(ctx, AV_LOG_ERROR, "Failed to create fluidsynth settings\n");
> +        return AVERROR_UNKNOWN;

I'm not sure this is the correct error. If the library can only fail
due to lack of memory, this should be AVERROR(ENOMEM). Else failing
external library calls lead to AVERROR_EXTERNAL.

> +    if(fluidsynth->soundfont_id < 0) {
> +        av_log(ctx, AV_LOG_ERROR, "Failed to load soundfont\n");
> +    }

Shouldn't this also lead to an error being returned?
OTOH, if it isn't fatal, the log message should be a warning.

> +    return 0;
> +}

Cheers,
Moritz
Marshall Murmu March 16, 2020, 11:19 a.m. UTC | #3
On Mon, Mar 16, 2020 at 3:40 PM Moritz Barsnick <barsnick@gmx.net> wrote:

> Hi Marshall,
>
> On Sat, Mar 14, 2020 at 15:58:32 +0530, Marshall Murmu wrote:
>
> > +    {"soundfont",   "location of soundfont",
>  OFFSET(soundfont),   AV_OPT_TYPE_STRING,   {.str=NULL},     CHAR_MIN,
> CHAR_MAX,  FLAGS},
>
> I don't think we define ranges for AV_OPT_TYPE_STRING.
>
 I looked at other filters and found that some had defined the ranges as
(CHAR_MIN, CHAR_MAX) or (0,0)  or the range was not defined. So I didn't
think it would be an issue.

> +    if(fluidsynth->settings == NULL) {
>
> As Paul mentioned, whitespace style (throughout the complete source).
>
> Also, "if (!fluidsynth->settings)" is the preferred style.
>
Will fix it in next patch.

> +        av_log(ctx, AV_LOG_ERROR, "Failed to create fluidsynth
> settings\n");
> > +        return AVERROR_UNKNOWN;
>
> I'm not sure this is the correct error. If the library can only fail
> due to lack of memory, this should be AVERROR(ENOMEM). Else failing
> external library calls lead to AVERROR_EXTERNAL.
>
Fixing it.


> > +    if(fluidsynth->soundfont_id < 0) {
> > +        av_log(ctx, AV_LOG_ERROR, "Failed to load soundfont\n");
> > +    }
>
> Shouldn't this also lead to an error being returned?
> OTOH, if it isn't fatal, the log message should be a warning.
>
Yes, it should return an error. Fluidsynth requires a soundfont to
synthesize the tones. Without a soundfont it won't be able to generate any
sound. Will fix it in next patch.
Anton Khirnov March 16, 2020, 3:02 p.m. UTC | #4
Quoting Marshall Murmu (2020-03-16 12:19:55)
> On Mon, Mar 16, 2020 at 3:40 PM Moritz Barsnick <barsnick@gmx.net> wrote:
> 
> > Hi Marshall,
> >
> > On Sat, Mar 14, 2020 at 15:58:32 +0530, Marshall Murmu wrote:
> >
> > > +    {"soundfont",   "location of soundfont",
> >  OFFSET(soundfont),   AV_OPT_TYPE_STRING,   {.str=NULL},     CHAR_MIN,
> > CHAR_MAX,  FLAGS},
> >
> > I don't think we define ranges for AV_OPT_TYPE_STRING.
> >
>  I looked at other filters and found that some had defined the ranges as
> (CHAR_MIN, CHAR_MAX) or (0,0)  or the range was not defined. So I didn't
> think it would be an issue.

That is a cargo cult and has no effect whatsoever. Better not set it at
all to avoid propagating this misunderstanding.
diff mbox series

Patch

diff --git a/Changelog b/Changelog
index d1572553a5..5ddd2484b0 100644
--- a/Changelog
+++ b/Changelog
@@ -48,6 +48,7 @@  version <next>:
 - AMQP 0-9-1 protocol (RabbitMQ)
 - Vulkan support
 - avgblur_vulkan, overlay_vulkan, scale_vulkan and chromaber_vulkan filters
+- atone filter
 
 
 version 4.2:
diff --git a/configure b/configure
index 6ceb0c7af4..be48a22770 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
@@ -3465,6 +3467,7 @@  asr_filter_deps="pocketsphinx"
 ass_filter_deps="libass"
 atempo_filter_deps="avcodec"
 atempo_filter_select="rdft"
+atone_filter_deps="libfluidsynth"
 avgblur_opencl_filter_deps="opencl"
 avgblur_vulkan_filter_deps="vulkan libglslang"
 azmq_filter_deps="libzmq"
@@ -6270,6 +6273,7 @@  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 328e984e92..0ef3e83e65 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -5946,6 +5946,35 @@  anullsrc=r=48000:cl=mono
 
 All the parameters need to be explicitly defined.
 
+@section atone
+
+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.
+
+@item seed
+Set the seed value for the PRNG
+@end table
+
 @section flite
 
 Synthesize a voice utterance using the libflite library.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 750412da6b..020c4553cb 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -147,6 +147,7 @@  OBJS-$(CONFIG_AEVALSRC_FILTER)               += aeval.o
 OBJS-$(CONFIG_AFIRSRC_FILTER)                += asrc_afirsrc.o
 OBJS-$(CONFIG_ANOISESRC_FILTER)              += asrc_anoisesrc.o
 OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
+OBJS-$(CONFIG_ATONE_FILTER)                  += asrc_atone.o
 OBJS-$(CONFIG_FLITE_FILTER)                  += asrc_flite.o
 OBJS-$(CONFIG_HILBERT_FILTER)                += asrc_hilbert.o
 OBJS-$(CONFIG_SINC_FILTER)                   += asrc_sinc.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 501e5d041b..d167499cf1 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -141,6 +141,7 @@  extern AVFilter ff_asrc_aevalsrc;
 extern AVFilter ff_asrc_afirsrc;
 extern AVFilter ff_asrc_anoisesrc;
 extern AVFilter ff_asrc_anullsrc;
+extern AVFilter ff_asrc_atone;
 extern AVFilter ff_asrc_flite;
 extern AVFilter ff_asrc_hilbert;
 extern AVFilter ff_asrc_sinc;
diff --git a/libavfilter/asrc_atone.c b/libavfilter/asrc_atone.c
new file mode 100644
index 0000000000..f3ebab906e
--- /dev/null
+++ b/libavfilter/asrc_atone.c
@@ -0,0 +1,172 @@ 
+/*
+ * 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 AToneContext {
+    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;
+    int64_t seed;
+    AVLFG c;
+} AToneContext;
+
+#define OFFSET(x) offsetof(AToneContext, x)
+#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption atone_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},
+    {"seed",        "set random seed",                           OFFSET(seed),        AV_OPT_TYPE_INT64,    {.i64=-1},       -1,       INT64_MAX, FLAGS},
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(atone);
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    AToneContext *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)
+{
+    AToneContext *fluidsynth = ctx->priv;
+    delete_fluid_synth(fluidsynth->synth);
+    delete_fluid_settings(fluidsynth->settings);
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    AToneContext *fluidsynth = ctx->priv;
+    AVFilterChannelLayouts *chanlayout = NULL;
+    int64_t chanlayouts = av_get_default_channel_layout(2*fluid_synth_count_audio_channels(fluidsynth->synth));
+    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;
+    AToneContext *fluidsynth = ctx->priv;
+
+    if(fluidsynth->seed == -1)
+        fluidsynth->seed = av_get_random_seed();
+    av_lfg_init(&fluidsynth->c, fluidsynth->seed);
+
+    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;
+    AToneContext *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 atone_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_AUDIO,
+        .request_frame = request_frame,
+        .config_props  = config_output,
+    },
+    { NULL }
+};
+
+AVFilter ff_asrc_atone = {
+    .name          = "atone",
+    .description   = NULL_IF_CONFIG_SMALL("Synthesize tones using libfluidsynth."),
+    .query_formats = query_formats,
+    .init          = init,
+    .uninit        = uninit,
+    .priv_size     = sizeof(AToneContext),
+    .inputs        = NULL,
+    .outputs       = atone_outputs,
+    .priv_class    = &atone_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