Commit 1ee410f3 authored by Stefano Sabatini's avatar Stefano Sabatini
Browse files

Add asrc_anullsrc - null audio source.

Based on a patch by "S.N. Hemanth Meenakshisundaram" smeenaks!ucsd!edu.

Originally committed as revision 25188 to svn://svn.ffmpeg.org/ffmpeg/trunk
parent 6afd569e
......@@ -14,6 +14,40 @@ Pass the audio source unchanged to the output.
@c man end AUDIO FILTERS
@chapter Audio Sources
@c man begin AUDIO SOURCES
Below is a description of the currently available audio sources.
@section anullsrc
Null audio source, never return audio frames. It is mainly useful as a
template and to be employed in analysis / debugging tools.
It accepts as optional parameter a string of the form
@var{sample_rate}:@var{channel_layout}.
@var{sample_rate} specify the sample rate, and defaults to 44100.
@var{channel_layout} specify the channel layout, and can be either an
integer or a string representing a channel layout. The default value
of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
Check the channel_layout_map definition in
@file{libavcodec/audioconvert.c} for the correspondance between string
and channel layout values.
Follow some examples:
@example
# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
anullsrc=48000:4
# same as
anullsrc=48000:mono
@end example
@c man end AUDIO SOURCES
@chapter Video Filters
@c man begin VIDEO FILTERS
......
......@@ -16,6 +16,8 @@ OBJS = allfilters.o \
OBJS-$(CONFIG_ANULL_FILTER) += af_anull.o
OBJS-$(CONFIG_ANULLSRC_FILTER) += asrc_anullsrc.o
OBJS-$(CONFIG_ASPECT_FILTER) += vf_aspect.o
OBJS-$(CONFIG_CROP_FILTER) += vf_crop.o
OBJS-$(CONFIG_FIFO_FILTER) += vf_fifo.o
......
......@@ -36,6 +36,8 @@ void avfilter_register_all(void)
REGISTER_FILTER (ANULL, anull, af);
REGISTER_FILTER (ANULLSRC, anullsrc, asrc);
REGISTER_FILTER (ASPECT, aspect, vf);
REGISTER_FILTER (CROP, crop, vf);
REGISTER_FILTER (FIFO, fifo, vf);
......
/*
* 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
* null audio source
*/
#include "avfilter.h"
#include "libavcodec/audioconvert.h"
typedef struct {
int64_t channel_layout;
int64_t sample_rate;
} ANullContext;
static int init(AVFilterContext *ctx, const char *args, void *opaque)
{
ANullContext *priv = ctx->priv;
char channel_layout_str[128] = "";
priv->sample_rate = 44100;
priv->channel_layout = CH_LAYOUT_STEREO;
if (args)
sscanf(args, "%"PRId64":%s", &priv->sample_rate, channel_layout_str);
if (priv->sample_rate < 0) {
av_log(ctx, AV_LOG_ERROR, "Invalid negative sample rate: %"PRId64"\n", priv->sample_rate);
return AVERROR(EINVAL);
}
if (*channel_layout_str)
if (!(priv->channel_layout = avcodec_get_channel_layout(channel_layout_str))
&& sscanf(channel_layout_str, "%"PRId64, &priv->channel_layout) != 1) {
av_log(ctx, AV_LOG_ERROR, "Invalid value '%s' for channel layout\n",
channel_layout_str);
return AVERROR(EINVAL);
}
return 0;
}
static int config_props(AVFilterLink *outlink)
{
ANullContext *priv = outlink->src->priv;
char buf[128];
int chans_nb;
outlink->sample_rate = priv->sample_rate;
outlink->channel_layout = priv->channel_layout;
chans_nb = avcodec_channel_layout_num_channels(priv->channel_layout);
avcodec_get_channel_layout_string(buf, sizeof(buf), chans_nb, priv->channel_layout);
av_log(outlink->src, AV_LOG_INFO,
"sample_rate:%"PRId64 " channel_layout:%"PRId64 " channel_layout_description:'%s'\n",
priv->sample_rate, priv->channel_layout, buf);
return 0;
}
static int request_frame(AVFilterLink *link)
{
return -1;
}
AVFilter avfilter_asrc_anullsrc = {
.name = "anullsrc",
.description = NULL_IF_CONFIG_SMALL("Null audio source, never return audio frames."),
.init = init,
.priv_size = sizeof(ANullContext),
.inputs = (AVFilterPad[]) {{ .name = NULL}},
.outputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.config_props = config_props,
.request_frame = request_frame, },
{ .name = NULL}},
};
......@@ -25,7 +25,7 @@
#include "libavutil/avutil.h"
#define LIBAVFILTER_VERSION_MAJOR 1
#define LIBAVFILTER_VERSION_MINOR 42
#define LIBAVFILTER_VERSION_MINOR 43
#define LIBAVFILTER_VERSION_MICRO 0
#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
......
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