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}.
+It accepts an optional sequence of @var{key}=@var{value} pairs,
+separated by ":".
+
+The description of the accepted options follows.
-@var{sample_rate} specify the sample rate, and defaults to 44100.
+@table @option
+
+@item sample_rate, s
+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.
+@item channel_layout, cl
+
+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 "stereo".
Check the channel_layout_map definition in
@file{libavcodec/audioconvert.c} for the mapping between strings and
channel layout values.
+@end table
Follow some examples:
@example
-# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
-anullsrc=48000:4
+# set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
+anullsrc=r=48000:cl=4
# same as
-anullsrc=48000:mono
+anullsrc=r=48000:cl=mono
@end example
@c man end AUDIO SOURCES
* null audio source
*/
-#include "avfilter.h"
#include "libavutil/audioconvert.h"
+#include "libavutil/opt.h"
+
+#include "avfilter.h"
+#include "internal.h"
typedef struct {
+ const AVClass *class;
+ char *channel_layout_str;
int64_t channel_layout;
- int64_t sample_rate;
+ char *sample_rate_str;
+ int sample_rate;
} ANullContext;
+#define OFFSET(x) offsetof(ANullContext, x)
+
+static const AVOption anullsrc_options[]= {
+ { "channel_layout", "set channel_layout", OFFSET(channel_layout_str), FF_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0 },
+ { "cl", "set channel_layout", OFFSET(channel_layout_str), FF_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0 },
+ { "sample_rate", "set sample rate", OFFSET(sample_rate_str) , FF_OPT_TYPE_STRING, {.str = "44100"}, 0, 0 },
+ { "r", "set sample rate", OFFSET(sample_rate_str) , FF_OPT_TYPE_STRING, {.str = "44100"}, 0, 0 },
+ { NULL },
+};
+
+static const char *anullsrc_get_name(void *ctx)
+{
+ return "anullsrc";
+}
+
+static const AVClass anullsrc_class = {
+ "ANullSrcContext",
+ anullsrc_get_name,
+ anullsrc_options
+};
+
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 = AV_CH_LAYOUT_STEREO;
+ int ret;
- if (args)
- sscanf(args, "%"PRId64":%s", &priv->sample_rate, channel_layout_str);
+ priv->class = &anullsrc_class;
+ av_opt_set_defaults(priv);
- if (priv->sample_rate < 0) {
- av_log(ctx, AV_LOG_ERROR, "Invalid negative sample rate: %"PRId64"\n", priv->sample_rate);
- return AVERROR(EINVAL);
+ if ((ret = (av_set_options_string(priv, args, "=", ":"))) < 0) {
+ av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
+ return ret;
}
- if (*channel_layout_str)
- if (!(priv->channel_layout = av_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);
- }
+ if ((ret = ff_parse_sample_rate(&priv->sample_rate,
+ priv->sample_rate_str, ctx)) < 0)
+ return ret;
+
+ if ((ret = ff_parse_channel_layout(&priv->channel_layout,
+ priv->channel_layout_str, ctx)) < 0)
+ return ret;
return 0;
}
chans_nb = av_get_channel_layout_nb_channels(priv->channel_layout);
av_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",
+ "sample_rate:%d channel_layout:%"PRId64 " channel_layout_description:'%s'\n",
priv->sample_rate, priv->channel_layout, buf);
return 0;