[FFmpeg-devel] [ffmpeg-devel] [PATCH 2/4] lavfi: add asink_abuffer - audio sink buffer filter

Stefano Sabatini stefano.sabatini-lala at poste.it
Tue Aug 2 00:33:35 CEST 2011


On date Monday 2011-08-01 12:35:20 +0300, Mina Nagy Zaki encoded:
> Docs were misplaced, here's an update patch.
> 

> From ef654af6cd673cc9283b4dc393b26180f68cd861 Mon Sep 17 00:00:00 2001
> From: Mina Nagy Zaki <mnzaki at gmail.com>
> Date: Thu, 7 Jul 2011 00:26:16 +0300
> Subject: [PATCH 03/11] lavfi: add asink_abuffer - audio sink buffer filter
> 
> ---
>  doc/filters.texi            |   11 +++++
>  libavfilter/Makefile        |    1 +
>  libavfilter/allfilters.c    |    1 +
>  libavfilter/asink_abuffer.c |  100 +++++++++++++++++++++++++++++++++++++++++++
>  libavfilter/asink_abuffer.h |   48 ++++++++++++++++++++
>  5 files changed, 161 insertions(+), 0 deletions(-)
>  create mode 100644 libavfilter/asink_abuffer.c
>  create mode 100644 libavfilter/asink_abuffer.h
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index dd1a1ee..5538848 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -210,6 +210,17 @@ anullsrc=48000:mono
>  
>  Below is a description of the currently available audio sinks.
>  
> + at section abuffersink
> +
> +Buffer audio frames, and make them available to the end of filter chain.
> +
> +This sink is mainly intended for programmatic use, in particular
> +through the interface defined in @file{libavfilter/asink_abuffer.h}.
> +
> +It requires a pointer to a ABufferSinkContext structure, which defines the
> +incoming buffers' format, to be passed as the opaque parameter to
> + at code{avfilter_init_filter} for initialization.
> +
>  @section anullsink
>  
>  Null audio sink, do absolutely nothing with the input audio. It is
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 686fd30..83b906d 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -23,6 +23,7 @@ OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
>  
>  OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
>  
> +OBJS-$(CONFIG_ABUFFERSINK_FILTER)            += asink_abuffer.o
>  OBJS-$(CONFIG_ANULLSINK_FILTER)              += asink_anullsink.o
>  
>  OBJS-$(CONFIG_BLACKFRAME_FILTER)             += vf_blackframe.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 49be7b7..b812ff7 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -40,6 +40,7 @@ void avfilter_register_all(void)
>      REGISTER_FILTER (ABUFFER,     abuffer,     asrc);
>      REGISTER_FILTER (ANULLSRC,    anullsrc,    asrc);
>  
> +    REGISTER_FILTER (ABUFFER,     abuffersink, asink);
>      REGISTER_FILTER (ANULLSINK,   anullsink,   asink);
>  
>      REGISTER_FILTER (BLACKFRAME,  blackframe,  vf);
> diff --git a/libavfilter/asink_abuffer.c b/libavfilter/asink_abuffer.c
> new file mode 100644
> index 0000000..90a91f7
> --- /dev/null
> +++ b/libavfilter/asink_abuffer.c
> @@ -0,0 +1,100 @@
> +/*
> + * Copyright (c) 2011 Stefano Sabatini
> + * Copyright (c) 2011 Mina Nagy Zaki
> + *
> + * 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
> + * audio buffer sink
> + */
> +
> +#include "avfilter.h"
> +#include "asink_abuffer.h"
> +
> +static void filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref)
> +{
> +}
> +
> +static int init(AVFilterContext *ctx, const char *args, void *opaque)
> +{
> +    if (!opaque) {
> +        av_log(ctx, AV_LOG_ERROR, "Opaque field required, please pass"
> +                                  " an initialized ABufferSinkContext");
> +        return AVERROR(EINVAL);
> +    }
> +    memcpy(ctx->priv, opaque, sizeof(ABufferSinkContext));
> +
> +    return 0;
> +}
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> +    ABufferSinkContext *abuffersink = ctx->priv;
> +    AVFilterFormats *formats;
> +    int ret;
> +
> +    formats = NULL;
> +    if ((ret = avfilter_add_format(&formats, abuffersink->sample_fmt)) < 0)
> +        return ret;
> +    avfilter_set_common_sample_formats(ctx, formats);
> +
> +    formats = NULL;
> +    if ((ret = avfilter_add_format(&formats, abuffersink->channel_layout)) < 0)
> +        return ret;
> +    avfilter_set_common_channel_layouts(ctx, formats);
> +
> +    formats = NULL;
> +    if ((ret = avfilter_add_format(&formats, abuffersink->planar)) < 0)
> +        return ret;
> +    avfilter_set_common_packing_formats(ctx, formats);
> +
> +    return 0;
> +}
> +
> +int av_asink_abuffer_get_audio_buffer_ref(AVFilterContext *abuffersink,
> +                                          AVFilterBufferRef **samplesref,
> +                                          int av_unused flags)
> +{
> +    int ret;
> +
> +    if ((ret = avfilter_request_frame(abuffersink->inputs[0])))

Nit: abuffersink->inputs[0] -> inlink may help readability

> +        return ret;
> +    if (!abuffersink->inputs[0]->cur_buf)
> +        return AVERROR(EINVAL);
> +    *samplesref = abuffersink->inputs[0]->cur_buf;
> +    abuffersink->inputs[0]->cur_buf = NULL;
> +
> +    return 0;
> +}
> +
> +AVFilter avfilter_asink_abuffersink = {
> +    .name      = "abuffersink",
> +    .description = NULL_IF_CONFIG_SMALL("Buffer audio frames, and make them available to the end of the filter graph."),
> +    .init      = init,
> +    .priv_size = sizeof(ABufferSinkContext),
> +    .query_formats = query_formats,
> +
> +    .inputs    = (AVFilterPad[]) {{ .name           = "default",
> +                                    .type           = AVMEDIA_TYPE_AUDIO,
> +                                    .filter_samples = filter_samples,
> +                                    .min_perms      = AV_PERM_READ, },
> +                                  { .name = NULL }},
> +    .outputs   = (AVFilterPad[]) {{ .name = NULL }},
> +};
> +
> diff --git a/libavfilter/asink_abuffer.h b/libavfilter/asink_abuffer.h
> new file mode 100644
> index 0000000..a601b6b
> --- /dev/null
> +++ b/libavfilter/asink_abuffer.h
> @@ -0,0 +1,48 @@
> +/*
> + * 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
> + */
> +
> +#ifndef AVFILTER_ASINK_ABUFFER_H
> +#define AVFILTER_ASINK_ABUFFER_H
> +
> +/**
> + * @file
> + * audio buffer sink API
> + */
> +
> +#include "avfilter.h"
> +
> +typedef struct {
> +    enum AVSampleFormat sample_fmt;
> +    int64_t channel_layout;
> +    int planar;
> +} ABufferSinkContext;
> +
> +
> +/**
> + * Get an audio buffer from abuffersink and put it in samplesref.
> + *
> + * @param abuffersink pointer to an abuffersink context

> + * @param samplesref pointer to an AVFilterBufferRef* to put buffer
                                                         ^^^^^^^^^^^^^
typo?

nit++: maybe you can entirely skip the @param, but it would generate a
doxygen warning, so do as you prefer.

> + * @param flags unused
> + * @return >= 0 in case of success, a negative AVERROR code in case of failure
> + */
> +int av_asink_abuffer_get_audio_buffer_ref(AVFilterContext *abuffersink,
> +                                          AVFilterBufferRef **samplesref,
> +                                          int av_unused flags);
> +
> +#endif /* AVFILTER_ASINK_ABUFFER_H */

Looks fine otherwise.

Possible todos includes: support for a peek flag like in the video
sink, support for multiple frames caching (depends on av_fifo_peek2(),
can't yet be implemented).
-- 
FFmpeg = Freak Faithless Maxi Perennial Extroverse Gnome


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