[FFmpeg-devel] [PATCH] Add asetpts audio filter

Andrey Utkin andrey.krieger.utkin at gmail.com
Wed Feb 29 13:00:01 CET 2012


---
 libavfilter/Makefile     |    1 +
 libavfilter/af_asetpts.c |  145 ++++++++++++++++++++++++++++++++++++++++++++++
 libavfilter/allfilters.c |    1 +
 3 files changed, 147 insertions(+), 0 deletions(-)
 create mode 100644 libavfilter/af_asetpts.c

diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index db7397b..37e006e 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -31,6 +31,7 @@ OBJS-$(CONFIG_AFORMAT_FILTER)                += af_aformat.o
 OBJS-$(CONFIG_AMERGE_FILTER)                 += af_amerge.o
 OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
 OBJS-$(CONFIG_ARESAMPLE_FILTER)              += af_aresample.o
+OBJS-$(CONFIG_ASETPTS_FILTER)                += af_asetpts.o
 OBJS-$(CONFIG_ASHOWINFO_FILTER)              += af_ashowinfo.o
 OBJS-$(CONFIG_ASPLIT_FILTER)                 += af_asplit.o
 OBJS-$(CONFIG_ASTREAMSYNC_FILTER)            += af_astreamsync.o
diff --git a/libavfilter/af_asetpts.c b/libavfilter/af_asetpts.c
new file mode 100644
index 0000000..ed15f9b
--- /dev/null
+++ b/libavfilter/af_asetpts.c
@@ -0,0 +1,145 @@
+/*
+ * Copyright (c) 2012 Andrey Utkin
+ * Copyright (c) 2010 Stefano Sabatini
+ * Copyright (c) 2008 Victor Paesa
+ *
+ * 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 presentation timestamp (PTS) modification filter
+ */
+
+/* #define DEBUG */
+
+#include "libavutil/eval.h"
+#include "libavutil/mathematics.h"
+#include "avfilter.h"
+
+static const char *const var_names[] = {
+    "N",           ///< frame number (starting at zero)
+    "POS",         ///< original position in the file of the frame
+    "PREV_INPTS",  ///< previous  input PTS
+    "PREV_OUTPTS", ///< previous output PTS
+    "PTS",         ///< original pts in the file of the frame
+    "STARTPTS",   ///< PTS at start of movie
+    "TB",          ///< timebase
+    NULL
+};
+
+enum var_name {
+    VAR_N,
+    VAR_POS,
+    VAR_PREV_INPTS,
+    VAR_PREV_OUTPTS,
+    VAR_PTS,
+    VAR_STARTPTS,
+    VAR_TB,
+    VAR_VARS_NB
+};
+
+typedef struct {
+    AVExpr *expr;
+    double var_values[VAR_VARS_NB];
+} SetPTSContext;
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    SetPTSContext *setpts = ctx->priv;
+    int ret;
+
+    if ((ret = av_expr_parse(&setpts->expr, args ? args : "PTS",
+                             var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
+        av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);
+        return ret;
+    }
+
+    setpts->var_values[VAR_N          ] = 0.0;
+    setpts->var_values[VAR_PREV_INPTS ] = NAN;
+    setpts->var_values[VAR_PREV_OUTPTS] = NAN;
+    setpts->var_values[VAR_STARTPTS   ] = NAN;
+    return 0;
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    SetPTSContext *setpts = inlink->dst->priv;
+
+    setpts->var_values[VAR_TB] = av_q2d(inlink->time_base);
+
+    av_log(inlink->src, AV_LOG_INFO, "TB:%f\n", setpts->var_values[VAR_TB]);
+    return 0;
+}
+
+#define D2TS(d)  (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
+#define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
+
+static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
+{
+    SetPTSContext *setpts = inlink->dst->priv;
+    double d;
+    AVFilterBufferRef *outpicref = avfilter_ref_buffer(inpicref, ~0);
+
+    if (isnan(setpts->var_values[VAR_STARTPTS]))
+        setpts->var_values[VAR_STARTPTS] = TS2D(inpicref->pts);
+
+    setpts->var_values[VAR_PTS] = TS2D(inpicref->pts);
+    setpts->var_values[VAR_POS] = inpicref->pos == -1 ? NAN : inpicref->pos;
+
+    d = av_expr_eval(setpts->expr, setpts->var_values, NULL);
+    outpicref->pts = D2TS(d);
+
+#ifdef DEBUG
+    av_log(inlink->dst, AV_LOG_DEBUG,
+           "n:%"PRId64" pos:%"PRId64" pts:%"PRId64" t:%f -> pts:%"PRId64" t:%f\n",
+           (int64_t)setpts->var_values[VAR_N],
+           inpicref ->pos,
+           inpicref ->pts, inpicref ->pts * av_q2d(inlink->time_base),
+           outpicref->pts, outpicref->pts * av_q2d(inlink->time_base));
+#endif
+
+    setpts->var_values[VAR_N] += 1.0;
+    setpts->var_values[VAR_PREV_INPTS ] = TS2D(inpicref ->pts);
+    setpts->var_values[VAR_PREV_OUTPTS] = TS2D(outpicref->pts);
+    avfilter_filter_samples(inlink->dst->outputs[0], outpicref);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    SetPTSContext *setpts = ctx->priv;
+    av_expr_free(setpts->expr);
+    setpts->expr = 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),
+
+    .inputs    = (const AVFilterPad[]) {{ .name       = "default",
+                                    .type             = AVMEDIA_TYPE_AUDIO,
+                                    .config_props     = config_input,
+                                    .filter_samples   = filter_samples, },
+                                  { .name = NULL }},
+    .outputs   = (const AVFilterPad[]) {{ .name       = "default",
+                                    .type             = AVMEDIA_TYPE_AUDIO, },
+                                  { .name = NULL}},
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 339ef8d..b7dd730 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -39,6 +39,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (AMERGE,      amerge,      af);
     REGISTER_FILTER (ANULL,       anull,       af);
     REGISTER_FILTER (ARESAMPLE,   aresample,   af);
+    REGISTER_FILTER (ASETPTS,     asetpts,     af);
     REGISTER_FILTER (ASHOWINFO,   ashowinfo,   af);
     REGISTER_FILTER (ASPLIT,      asplit,      af);
     REGISTER_FILTER (ASTREAMSYNC, astreamsync, af);
-- 
1.7.7



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