lavfi: add an asetpts filter

Changelog

@@ -12,6 +12,7 @@ version 10:
 - uniform options syntax across all filters
 - new interlace filter
 - JPEG 2000 decoder
+- new asetpts filter (same as setpts, but for audio)
 
 
 version 9:

doc/filters.texi

@@ -192,6 +192,75 @@ stream ends. The default value is 2 seconds.
 
 Pass the audio source unchanged to the output.
 
+@section asetpts
+
+Change the PTS (presentation timestamp) of the input audio frames.
+
+This filter accepts the following options:
+
+@table @option
+
+@item expr
+The expression which is evaluated for each frame to construct its timestamp.
+
+@end table
+
+The expression is evaluated through the eval API and can contain the following
+constants:
+
+@table @option
+@item PTS
+the presentation timestamp in input
+
+@item PI
+Greek PI
+
+@item PHI
+golden ratio
+
+@item E
+Euler number
+
+@item N
+Number of the audio samples pass through the filter so far, starting at 0.
+
+@item S
+Number of the audio samples in the current frame.
+
+@item SR
+Audio sample rate.
+
+@item STARTPTS
+the PTS of the first frame
+
+@item PREV_INPTS
+previous input PTS
+
+@item PREV_OUTPTS
+previous output PTS
+
+@item RTCTIME
+wallclock (RTC) time in microseconds
+
+@item RTCSTART
+wallclock (RTC) time at the start of the movie in microseconds
+
+@end table
+
+Some examples follow:
+
+@example
+# start counting PTS from zero
+asetpts=expr=PTS-STARTPTS
+
+#generate timestamps by counting samples
+asetpts=expr=N/SR/TB
+
+# generate timestamps from a "live source" and rebase onto the current timebase
+asetpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
+@end example
+
+
 @section ashowinfo
 
 Show a line containing various information for each input audio frame.

libavfilter/Makefile

@@ -27,6 +27,7 @@ OBJS = allfilters.o                                                     \
 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-$(CONFIG_ASHOWINFO_FILTER)              += af_ashowinfo.o
 OBJS-$(CONFIG_ASPLIT_FILTER)                 += split.o
 OBJS-$(CONFIG_ASYNCTS_FILTER)                += af_asyncts.o
@@ -70,7 +71,7 @@ OBJS-$(CONFIG_PIXDESCTEST_FILTER)            += vf_pixdesctest.o
 OBJS-$(CONFIG_SCALE_FILTER)                  += vf_scale.o
 OBJS-$(CONFIG_SELECT_FILTER)                 += vf_select.o
 OBJS-$(CONFIG_SETDAR_FILTER)                 += vf_aspect.o
-OBJS-$(CONFIG_SETPTS_FILTER)                 += vf_setpts.o
+OBJS-$(CONFIG_SETPTS_FILTER)                 += setpts.o
 OBJS-$(CONFIG_SETSAR_FILTER)                 += vf_aspect.o
 OBJS-$(CONFIG_SETTB_FILTER)                  += vf_settb.o
 OBJS-$(CONFIG_SHOWINFO_FILTER)               += vf_showinfo.o

libavfilter/allfilters.c

@@ -47,6 +47,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(AFORMAT,        aformat,        af);
     REGISTER_FILTER(AMIX,           amix,           af);
     REGISTER_FILTER(ANULL,          anull,          af);
+    REGISTER_FILTER(ASETPTS,        asetpts,        af);
     REGISTER_FILTER(ASHOWINFO,      ashowinfo,      af);
     REGISTER_FILTER(ASPLIT,         asplit,         af);
     REGISTER_FILTER(ASYNCTS,        asyncts,        af);

libavfilter/setpts.c

@@ -31,14 +31,18 @@
 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"
 #include "libavutil/time.h"
+
+#include "audio.h"
 #include "avfilter.h"
 #include "internal.h"
 #include "video.h"
 
+#include "config.h"
+
 static const char *const var_names[] = {
     "E",           ///< Euler number
     "INTERLACED",  ///< tell if the current frame is interlaced
-    "N",           ///< frame number (starting at zero)
+    "N",           ///< frame / sample number (starting at zero)
     "PHI",         ///< golden ratio
     "PI",          ///< greek pi
     "PREV_INPTS",  ///< previous  input PTS
@@ -48,6 +52,8 @@ static const char *const var_names[] = {
     "TB",          ///< timebase
     "RTCTIME",     ///< wallclock (RTC) time in micro seconds
     "RTCSTART",    ///< wallclock (RTC) time at the start of the movie in micro seconds
+    "S",           //   Number of samples in the current frame
+    "SR",          //   Audio sample rate
     NULL
 };
 
@@ -64,6 +70,8 @@ enum var_name {
     VAR_TB,
     VAR_RTCTIME,
     VAR_RTCSTART,
+    VAR_S,
+    VAR_SR,
     VAR_VARS_NB
 };
 
@@ -87,6 +95,7 @@ static av_cold int init(AVFilterContext *ctx)
 
     setpts->var_values[VAR_E]           = M_E;
     setpts->var_values[VAR_N]           = 0.0;
+    setpts->var_values[VAR_S]           = 0.0;
     setpts->var_values[VAR_PHI]         = M_PHI;
     setpts->var_values[VAR_PI]          = M_PI;
     setpts->var_values[VAR_PREV_INPTS]  = NAN;
@@ -102,6 +111,10 @@ static int config_input(AVFilterLink *inlink)
     setpts->var_values[VAR_TB] = av_q2d(inlink->time_base);
     setpts->var_values[VAR_RTCSTART] = av_gettime();
 
+    if (inlink->type == AVMEDIA_TYPE_AUDIO) {
+        setpts->var_values[VAR_SR] = inlink->sample_rate;
+    }
+
     av_log(inlink->src, AV_LOG_VERBOSE, "TB:%f\n", setpts->var_values[VAR_TB]);
     return 0;
 }
@@ -118,10 +131,15 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
     if (isnan(setpts->var_values[VAR_STARTPTS]))
         setpts->var_values[VAR_STARTPTS] = TS2D(frame->pts);
 
-    setpts->var_values[VAR_INTERLACED] = frame->interlaced_frame;
     setpts->var_values[VAR_PTS       ] = TS2D(frame->pts);
     setpts->var_values[VAR_RTCTIME   ] = av_gettime();
 
+    if (inlink->type == AVMEDIA_TYPE_VIDEO) {
+        setpts->var_values[VAR_INTERLACED] = frame->interlaced_frame;
+    } else {
+        setpts->var_values[VAR_S] = frame->nb_samples;
+    }
+
     d = av_expr_eval(setpts->expr, setpts->var_values, NULL);
     frame->pts = D2TS(d);
 
@@ -135,7 +153,12 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
 #endif
 
 
+    if (inlink->type == AVMEDIA_TYPE_VIDEO) {
         setpts->var_values[VAR_N] += 1.0;
+    } else {
+        setpts->var_values[VAR_N] += frame->nb_samples;
+    }
+
     setpts->var_values[VAR_PREV_INPTS ] = TS2D(in_pts);
     setpts->var_values[VAR_PREV_OUTPTS] = TS2D(frame->pts);
     return ff_filter_frame(inlink->dst->outputs[0], frame);
@@ -149,12 +172,13 @@ static av_cold void uninit(AVFilterContext *ctx)
 }
 
 #define OFFSET(x) offsetof(SetPTSContext, 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 frame timestamp", OFFSET(expr_str), AV_OPT_TYPE_STRING, { .str = "PTS" }, .flags = FLAGS },
     { NULL },
 };
 
+#if CONFIG_SETPTS_FILTER
 static const AVClass setpts_class = {
     .class_name = "setpts",
     .item_name  = av_default_item_name,
@@ -193,3 +217,45 @@ AVFilter avfilter_vf_setpts = {
     .inputs    = avfilter_vf_setpts_inputs,
     .outputs   = avfilter_vf_setpts_outputs,
 };
+#endif
+
+#if CONFIG_ASETPTS_FILTER
+static const AVClass asetpts_class = {
+    .class_name = "asetpts",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static const AVFilterPad asetpts_inputs[] = {
+    {
+        .name             = "default",
+        .type             = AVMEDIA_TYPE_AUDIO,
+        .get_audio_buffer = ff_null_get_audio_buffer,
+        .config_props     = config_input,
+        .filter_frame     = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad asetpts_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_AUDIO,
+    },
+    { NULL }
+};
+
+AVFilter avfilter_af_asetpts = {
+    .name        = "asetpts",
+    .description = NULL_IF_CONFIG_SMALL("Set PTS for the output audio frame."),
+    .init        = init,
+    .uninit      = uninit,
+
+    .priv_size  = sizeof(SetPTSContext),
+    .priv_class = &asetpts_class,
+
+    .inputs    = asetpts_inputs,
+    .outputs   = asetpts_outputs,
+};
+#endif

libavfilter/version.h

@@ -29,7 +29,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  8
+#define LIBAVFILTER_VERSION_MINOR  9
 #define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \