ffmpeg: add sdp_file option

Allow printing of sdp information to a file specified by -sdp_file
This allows users to print sdp information when at least one of the
outputs isn't an rtp stream.
Signed-off-by: Simon Thelen <ffmpeg-dev@c-14.de>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffmpeg.c

@@ -2270,16 +2270,34 @@ static void print_sdp(void)
 {
     char sdp[16384];
     int i;
+    int j;
+    AVIOContext *sdp_pb;
     AVFormatContext **avc = av_malloc_array(nb_output_files, sizeof(*avc));
 
     if (!avc)
         exit_program(1);
-    for (i = 0; i < nb_output_files; i++)
-        avc[i] = output_files[i]->ctx;
+    for (i = 0, j = 0; i < nb_output_files; i++) {
+        if (!strcmp(output_files[i]->ctx->oformat->name, "rtp")) {
+            avc[j] = output_files[i]->ctx;
+            j++;
+        }
+    }
+
+    av_sdp_create(avc, j, sdp, sizeof(sdp));
+
+    if (!sdp_filename) {
+        printf("SDP:\n%s\n", sdp);
+        fflush(stdout);
+    } else {
+        if (avio_open2(&sdp_pb, sdp_filename, AVIO_FLAG_WRITE, &int_cb, NULL) < 0) {
+            av_log(NULL, AV_LOG_ERROR, "Failed to open sdp file '%s'\n", sdp_filename);
+        } else {
+            avio_printf(sdp_pb, "SDP:\n%s", sdp);
+            avio_close(sdp_pb);
+            av_free(sdp_filename);
+        }
+    }
 
-    av_sdp_create(avc, nb_output_files, sdp, sizeof(sdp));
-    printf("SDP:\n%s\n", sdp);
-    fflush(stdout);
     av_freep(&avc);
 }
 
@@ -3122,7 +3140,7 @@ static int transcode_init(void)
         return ret;
     }
 
-    if (want_sdp) {
+    if (sdp_filename || want_sdp) {
         print_sdp();
     }
 

ffmpeg.h

@@ -470,6 +470,7 @@ extern FilterGraph **filtergraphs;
 extern int        nb_filtergraphs;
 
 extern char *vstats_filename;
+extern char *sdp_filename;
 
 extern float audio_drift_threshold;
 extern float dts_delta_threshold;

ffmpeg_opt.c

@@ -77,6 +77,7 @@ const HWAccel hwaccels[] = {
 };
 
 char *vstats_filename;
+char *sdp_filename;
 
 float audio_drift_threshold = 0.1;
 float dts_delta_threshold   = 10;
@@ -381,6 +382,13 @@ static int opt_map_channel(void *optctx, const char *opt, const char *arg)
     return 0;
 }
 
+static int opt_sdp_file(void *optctx, const char *opt, const char *arg)
+{
+    av_free(sdp_filename);
+    sdp_filename = av_strdup(arg);
+    return 0;
+}
+
 /**
  * Parse a metadata specifier passed as 'arg' parameter.
  * @param arg  metadata string to parse
@@ -3070,6 +3078,8 @@ const OptionDef options[] = {
         "set the initial demux-decode delay", "seconds" },
     { "override_ffserver", OPT_BOOL | OPT_EXPERT | OPT_OUTPUT, { &override_ffserver },
         "override the options from ffserver", "" },
+    { "sdp_file", HAS_ARG | OPT_EXPERT | OPT_OUTPUT, { opt_sdp_file },
+        "specify a file in which to print sdp information", "file" },
 
     { "bsf", HAS_ARG | OPT_STRING | OPT_SPEC | OPT_EXPERT | OPT_OUTPUT, { .off = OFFSET(bitstream_filters) },
         "A comma-separated list of bitstream filters", "bitstream_filters" },