[FFmpeg-devel] [PATCH] avfilter/WIP: add streamselect filter

Clément Bœsch u at pkh.me
Thu Nov 19 18:00:05 CET 2015


From: Clément Bœsch <clement at stupeflix.com>

---
No documentation so the concept is simply to map N streams to M other
streams, with the possibility to live configure the filter
(process_command).

For example, let's say you have 2 a/v inputs and you want to live
switch between the two, you will do something like:

  ffmpeg -i ... -i ... -lavfi "[0:0][0:1][1:0][1:1]streamselect=in=vava:out=va:map=0 1"

then send commands such as "map 0 1" or "map 2 3" to select one or
another source.

This is a WIP because I have a few issues right now (and also because
mostly untested):

- I always receive frames from the first input link... I suppose I need
  to write a "smart" request_frame callback, but things changed recently
  so maybe there are new guidelines for this? Nicolas, can I call for
  your help again?

- the command input in ffmpeg cli doesn't work anymore here (reproduce
  with: `ffmpeg -f lavfi -i testsrc -f null -` and press 'c': can't type
  anything then). I hacked something around to be able to send commands.

- sendcmd/zmq filters seem to need to be in the filtergraph itself to
  allow forwarding commands, and it doesn't seem possible to fit well
  with "multimedia" filters (we have sendcmd/asendcmd zmq/azmq)
---
 libavfilter/Makefile           |   1 +
 libavfilter/allfilters.c       |   1 +
 libavfilter/avf_streamselect.c | 215 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 217 insertions(+)
 create mode 100644 libavfilter/avf_streamselect.c

diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 1f4abeb..f2e6b0d 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -281,6 +281,7 @@ OBJS-$(CONFIG_SHOWSPECTRUM_FILTER)           += avf_showspectrum.o
 OBJS-$(CONFIG_SHOWVOLUME_FILTER)             += avf_showvolume.o
 OBJS-$(CONFIG_SHOWWAVES_FILTER)              += avf_showwaves.o
 OBJS-$(CONFIG_SHOWWAVESPIC_FILTER)           += avf_showwaves.o
+OBJS-$(CONFIG_STREAMSELECT_FILTER)           += avf_streamselect.o
 
 # multimedia sources
 OBJS-$(CONFIG_AMOVIE_FILTER)                 += src_movie.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 63b8fdb..cf805df 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -302,6 +302,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(SHOWVOLUME,     showvolume,     avf);
     REGISTER_FILTER(SHOWWAVES,      showwaves,      avf);
     REGISTER_FILTER(SHOWWAVESPIC,   showwavespic,   avf);
+    REGISTER_FILTER(STREAMSELECT,   streamselect,   avf);
 
     /* multimedia sources */
     REGISTER_FILTER(AMOVIE,         amovie,         avsrc);
diff --git a/libavfilter/avf_streamselect.c b/libavfilter/avf_streamselect.c
new file mode 100644
index 0000000..4a424ed
--- /dev/null
+++ b/libavfilter/avf_streamselect.c
@@ -0,0 +1,215 @@
+/*
+ * 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
+ */
+
+#include "libavutil/avstring.h"
+#include "libavutil/internal.h"
+#include "libavutil/opt.h"
+#include "avfilter.h"
+#include "audio.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+typedef struct StreamSelectContext {
+    const AVClass *class;
+    char *in_str;
+    char *out_str;
+    char *map_str;
+    int *map;
+    int nb_map;
+} StreamSelectContext;
+
+#define OFFSET(x) offsetof(StreamSelectContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM
+static const AVOption streamselect_options[] = {
+    { "in",  "input streams definition",          OFFSET(in_str),  AV_OPT_TYPE_STRING, {.str=NULL}, .flags=FLAGS },
+    { "out", "output streams definition",         OFFSET(out_str), AV_OPT_TYPE_STRING, {.str=NULL}, .flags=FLAGS },
+    { "map", "input indexes to remap to outputs", OFFSET(map_str), AV_OPT_TYPE_STRING, {.str=NULL}, .flags=FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(streamselect);
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
+{
+    int i;
+    AVFilterContext *ctx = inlink->dst;
+    StreamSelectContext *s = ctx->priv;
+    const int inlink_idx = FF_INLINK_IDX(inlink);
+
+    //av_log(0,0,"inlink %d %p\n", inlink_idx, inlink);
+
+    for (i = 0; i < s->nb_map; i++)
+        if (s->map[i] == inlink_idx)
+            return ff_filter_frame(ctx->outputs[i], frame);
+    av_frame_free(&frame);
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    StreamSelectContext *s = ctx->priv;
+    const int outlink_idx = FF_OUTLINK_IDX(outlink);
+    const int inlink_idx  = s->map[outlink_idx];
+    AVFilterLink *inlink = ctx->inputs[inlink_idx];
+
+    av_log(ctx, AV_LOG_DEBUG, "config output link %d "
+           "with settings from input link %d\n",
+           outlink_idx, inlink_idx);
+
+    outlink->w = inlink->w;
+    outlink->h = inlink->h;
+    outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;
+    return 0;
+}
+
+static int parse_definition(AVFilterContext *ctx, const char *def, void *filter_frame)
+{
+    const int is_input = !!filter_frame;
+    const char *padtype = is_input ? "in" : "out";
+    int i, ret = 0;
+
+    if (!def || !def[i]) {
+        av_log(ctx, AV_LOG_ERROR, "%sput streams definition is not set\n", padtype);
+        return AVERROR(EINVAL);
+    }
+
+    for (i = 0; def[i]; i++) {
+        AVFilterPad pad = { 0 };
+
+        switch (def[i]) {
+        case 'v':
+            pad.type = AVMEDIA_TYPE_VIDEO;
+            break;
+        case 'a':
+            pad.type = AVMEDIA_TYPE_AUDIO;
+            break;
+        default:
+            av_log(ctx, AV_LOG_ERROR, "Unknown/unsupported '%c' stream type\n", def[i]);
+            return AVERROR(EINVAL);
+        }
+
+        pad.name = av_asprintf("%sput%d", padtype, i);
+        if (!pad.name)
+            return AVERROR(ENOMEM);
+
+        av_log(ctx, AV_LOG_DEBUG, "Add %s pad %s\n", padtype, pad.name);
+
+        if (is_input) {
+            pad.filter_frame = filter_frame;
+            ret = ff_insert_inpad(ctx, i, &pad);
+        } else {
+            pad.config_props = config_output;
+            ret = ff_insert_outpad(ctx, i, &pad);
+        }
+
+        if (ret < 0) {
+            av_freep(&pad.name);
+            return ret;
+        }
+    }
+
+    return 0;
+}
+
+static int parse_mapping(AVFilterContext *ctx, const char *map)
+{
+    StreamSelectContext *s = ctx->priv;
+
+    av_freep(&s->map);
+    s->nb_map = 0;
+    s->map = av_malloc_array(ctx->nb_outputs, sizeof(*s->map));
+    if (!s->map)
+        return AVERROR(ENOMEM);
+
+    for (;;) {
+        char *p;
+        const int n = strtol(map, &p, 0);
+
+        av_log(0,0,"n=%d map=%p p=%p\n", n, map, p);
+
+        if (map == p)
+            break;
+        map = p;
+
+        if (s->nb_map >= ctx->nb_outputs) {
+            av_log(ctx, AV_LOG_ERROR, "Unable to map more than the %d "
+                   "output pads available\n", ctx->nb_outputs);
+            return AVERROR(EINVAL);
+        }
+
+        if (n < 0 || n >= ctx->nb_inputs) {
+            av_log(ctx, AV_LOG_ERROR, "Input stream index %d doesn't exist "
+                   "(there is only %d input streams defined)\n",
+                   n, ctx->nb_outputs);
+            return AVERROR(EINVAL);
+        }
+
+        av_log(ctx, AV_LOG_VERBOSE, "Map input stream %d to output stream %d\n", n, s->nb_map);
+        s->map[s->nb_map++] = n;
+    }
+
+    av_log(ctx, AV_LOG_VERBOSE, "%d map set\n", s->nb_map);
+
+    return 0;
+}
+
+static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
+                           char *res, int res_len, int flags)
+{
+    if (!strcmp(cmd, "map")) {
+        int ret = parse_mapping(ctx, args);
+        if (ret < 0)
+            return ret;
+        return avfilter_config_links(ctx);
+    }
+    return AVERROR(ENOSYS);
+}
+
+static av_cold int streamselect_init(AVFilterContext *ctx)
+{
+    int ret;
+    StreamSelectContext *s = ctx->priv;
+
+    if ((ret = parse_definition(ctx, s->in_str, filter_frame)) < 0 ||
+        (ret = parse_definition(ctx, s->out_str, NULL)) < 0)
+        return ret;
+
+    av_log(ctx, AV_LOG_DEBUG, "Configured with %d inpad and %d outpad\n",
+           ctx->nb_inputs, ctx->nb_outputs);
+
+    return parse_mapping(ctx, s->map_str);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    StreamSelectContext *s = ctx->priv;
+    av_freep(&s->map);
+}
+
+AVFilter ff_avf_streamselect = {
+    .name            = "streamselect",
+    .description     = NULL_IF_CONFIG_SMALL("Select streams"),
+    .init            = streamselect_init,
+    .process_command = process_command,
+    .uninit          = uninit,
+    .priv_size       = sizeof(StreamSelectContext),
+    .priv_class      = &streamselect_class,
+    .flags           = AVFILTER_FLAG_DYNAMIC_INPUTS | AVFILTER_FLAG_DYNAMIC_OUTPUTS,
+};
-- 
2.6.2



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