lavf/tee: allow multiple stream specifiers in select.

It makes possible to put multiple stream specifier into the select
option separated by comma.
eg. select=\'a:0,v\'

Signed-off-by: Bela Bodecs <bodecsb@vivanet.hu>
Signed-off-by: Nicolas George <george@nsup.org>

doc/muxers.texi

@@ -1272,7 +1272,8 @@ Several bitstream filters can be specified, separated by ",".
 @item select
 Select the streams that should be mapped to the slave output,
 specified by a stream specifier. If not specified, this defaults to
-all the input streams.
+all the input streams. You may use multiple stream specifiers
+separated by commas (@code{,}) e.g.: @code{a:0,v}
 @end table
 
 @subsection Examples

libavformat/tee.c

@@ -47,6 +47,7 @@ static const char *const slave_opt_open  = "[";
 static const char *const slave_opt_close = "]";
 static const char *const slave_opt_delim = ":]"; /* must have the close too */
 static const char *const slave_bsfs_spec_sep = "/";
+static const char *const slave_select_sep = ",";
 
 static const AVClass tee_muxer_class = {
     .class_name = "Tee muxer",
@@ -142,6 +143,8 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
     AVFormatContext *avf2 = NULL;
     AVStream *st, *st2;
     int stream_count;
+    int fullret;
+    char *subselect = NULL, *next_subselect = NULL, *first_subselect = NULL, *tmp_select = NULL;
 
     if ((ret = parse_slave_options(avf, slave, &options, &filename)) < 0)
         return ret;
@@ -172,15 +175,32 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
     for (i = 0; i < avf->nb_streams; i++) {
         st = avf->streams[i];
         if (select) {
-            ret = avformat_match_stream_specifier(avf, avf->streams[i], select);
+            tmp_select = av_strdup(select);  // av_strtok is destructive so we regenerate it in each loop
+            if (!tmp_select) {
+                ret = AVERROR(ENOMEM);
+                goto end;
+            }
+            fullret = 0;
+            first_subselect = tmp_select;
+            next_subselect = NULL;
+            while (subselect = av_strtok(first_subselect, slave_select_sep, &next_subselect)) {
+                first_subselect = NULL;
+
+                ret = avformat_match_stream_specifier(avf, avf->streams[i], subselect);
                 if (ret < 0) {
                     av_log(avf, AV_LOG_ERROR,
                            "Invalid stream specifier '%s' for output '%s'\n",
-                       select, slave);
+                           subselect, slave);
                     goto end;
                 }
+                if (ret != 0) {
+                    fullret = 1; // match
+                    break;
+                }
+            }
+            av_freep(&tmp_select);
 
-            if (ret == 0) { /* no match */
+            if (fullret == 0) { /* no match */
                 tee_slave->stream_map[i] = -1;
                 continue;
             }
@@ -282,6 +302,7 @@ end:
     av_free(format);
     av_free(select);
     av_dict_free(&options);
+    av_freep(&tmp_select);
     return ret;
 }