libavfilter: Add asettb filter for setting timebase for audio

Ported asettb (including the sr option for audio sample rate) from FFmpeg, and copied/modified the existing settb documentation for asettb. Signed-off-by: Katerina Barone-Adesi <[email protected]> Signed-off-by: Anton Khirnov <[email protected]>
zhengxj91 · Apr 10, 2014 · ad8159e · ad8159e
1 parent f6774f9
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Showing 6 changed files with 90 additions and 3 deletions.
diff --git a/Changelog b/Changelog
@@ -18,6 +18,7 @@ version <next>:
 - LucasArts SMUSH VIMA audio decoder (ADPCM)
 - LucasArts SMUSH demuxer
 - MP2 encoding via TwoLAME
+- asettb filter
 
 
 version 10:

diff --git a/doc/filters.texi b/doc/filters.texi
@@ -260,6 +260,47 @@ asetpts=expr=N/SR/TB
 asetpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
 @end example
 
+@section asettb
+
+Set the timebase to use for the output frames timestamps.
+It is mainly useful for testing timebase configuration.
+
+This filter accepts the following parameters:
+
+@table @option
+
+@item expr
+The expression which is evaluated into the output timebase.
+
+@end table
+
+The expression can contain the constants @var{PI}, @var{E}, @var{PHI}, @var{AVTB} (the
+default timebase), @var{intb} (the input timebase), and @var{sr} (the sample rate,
+audio only).
+
+The default value for the input is @var{intb}.
+
+Some examples:
+
+@example
+# Set the timebase to 1/25:
+settb=1/25
+
+# Set the timebase to 1/10:
+settb=0.1
+
+# Set the timebase to 1001/1000:
+settb=1+0.001
+
+# Set the timebase to 2*intb:
+settb=2*intb
+
+# Set the default timebase value:
+settb=AVTB
+
+# Set the timebase to twice the sample rate:
+asettb=sr*2
+@end example
 
 @section ashowinfo
 

diff --git a/libavfilter/Makefile b/libavfilter/Makefile
@@ -28,6 +28,7 @@ OBJS-$(CONFIG_AFORMAT_FILTER) += af_aformat.o
 OBJS-$(CONFIG_AMIX_FILTER) += af_amix.o
 OBJS-$(CONFIG_ANULL_FILTER) += af_anull.o
 OBJS-$(CONFIG_ASETPTS_FILTER) += setpts.o
+OBJS-$(CONFIG_ASETTB_FILTER) += settb.o
 OBJS-$(CONFIG_ASHOWINFO_FILTER) += af_ashowinfo.o
 OBJS-$(CONFIG_ASPLIT_FILTER) += split.o
 OBJS-$(CONFIG_ASYNCTS_FILTER) += af_asyncts.o

diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
@@ -48,6 +48,7 @@ void avfilter_register_all(void)
  REGISTER_FILTER(AMIX, amix, af);
  REGISTER_FILTER(ANULL, anull, af);
  REGISTER_FILTER(ASETPTS, asetpts, af);
+ REGISTER_FILTER(ASETTB, asettb, af);
  REGISTER_FILTER(ASHOWINFO, ashowinfo, af);
  REGISTER_FILTER(ASPLIT, asplit, af);
  REGISTER_FILTER(ASYNCTS, asyncts, af);

diff --git a/libavfilter/settb.c b/libavfilter/settb.c
@@ -32,6 +32,7 @@
 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"
 #include "libavutil/rational.h"
+#include "audio.h"
 #include "avfilter.h"
 #include "internal.h"
 #include "video.h"
@@ -42,6 +43,7 @@ static const char *const var_names[] = {
  "PI",
  "AVTB", /* default timebase 1/AV_TIME_BASE */
  "intb", /* input timebase */
+ "sr", /* sample rate */
  NULL
 };
 
@@ -51,6 +53,7 @@ enum var_name {
  VAR_PI,
  VAR_AVTB,
  VAR_INTB,
+ VAR_SR,
  VAR_VARS_NB
 };
 
@@ -74,6 +77,7 @@ static int config_output_props(AVFilterLink *outlink)
  settb->var_values[VAR_PI] = M_PI;
  settb->var_values[VAR_AVTB] = av_q2d(AV_TIME_BASE_Q);
  settb->var_values[VAR_INTB] = av_q2d(inlink->time_base);
+ settb->var_values[VAR_SR] = inlink->sample_rate;
 
  outlink->w = inlink->w;
  outlink->h = inlink->h;
@@ -116,12 +120,13 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
 }
 
 #define OFFSET(x) offsetof(SetTBContext, x)
-#define FLAGS AV_OPT_FLAG_VIDEO_PARAM
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_AUDIO_PARAM
 static const AVOption options[] = {
  { "expr", "Expression determining the output timebase", OFFSET(tb_expr), AV_OPT_TYPE_STRING, { .str = "intb" }, .flags = FLAGS },
  { NULL },
 };
 
+#if CONFIG_SETTB_FILTER
 static const AVClass settb_class = {
  .class_name = "settb",
  .item_name = av_default_item_name,
@@ -150,7 +155,7 @@ static const AVFilterPad avfilter_vf_settb_outputs[] = {
 
 AVFilter ff_vf_settb = {
  .name = "settb",
- .description = NULL_IF_CONFIG_SMALL("Set timebase for the output link."),
+ .description = NULL_IF_CONFIG_SMALL("Set timebase for the video output link."),
 
  .priv_size = sizeof(SetTBContext),
  .priv_class = &settb_class,
@@ -159,3 +164,41 @@ AVFilter ff_vf_settb = {
 
  .outputs = avfilter_vf_settb_outputs,
 };
+#endif /* CONFIG_SETTB_FILTER */
+
+#if CONFIG_ASETTB_FILTER
+static const AVClass asettb_class = {
+ .class_name = "asettb",
+ .item_name = av_default_item_name,
+ .option = options,
+ .version = LIBAVUTIL_VERSION_INT,
+};
+
+static const AVFilterPad avfilter_af_asettb_inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO,
+ .get_audio_buffer = ff_null_get_audio_buffer,
+ .filter_frame = filter_frame,
+ },
+ { NULL }
+};
+
+static const AVFilterPad avfilter_af_asettb_outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_AUDIO,
+ .config_props = config_output_props,
+ },
+ { NULL }
+};
+
+AVFilter ff_af_asettb = {
+ .name = "asettb",
+ .description = NULL_IF_CONFIG_SMALL("Set timebase for the audio output link."),
+ .priv_size = sizeof(SetTBContext),
+ .inputs = avfilter_af_asettb_inputs,
+ .outputs = avfilter_af_asettb_outputs,
+ .priv_class = &asettb_class,
+};
+#endif /* CONFIG_ASETTB_FILTER */
diff --git a/libavfilter/version.h b/libavfilter/version.h
@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR 4
-#define LIBAVFILTER_VERSION_MINOR 3
+#define LIBAVFILTER_VERSION_MINOR 4
 #define LIBAVFILTER_VERSION_MICRO 0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \