avformat/hlsenc: closed caption tags in the master playlist

doc/muxers.texi

@@ -901,6 +901,43 @@ and they are mapped to the two video only variant streams with audio group names
 
 By default, a single hls variant containing all the encoded streams is created.
 
+@item cc_stream_map
+Map string which specifies different closed captions groups and their
+attributes. The closed captions stream groups are separated by space.
+Expected string format is like this
+"ccgroup:<group name>,instreamid:<INSTREAM-ID>,language:<language code> ....".
+'ccgroup' and 'instreamid' are mandatory attributes. 'language' is an optional
+attribute.
+The closed captions groups configured using this option are mapped to different
+variant streams by providing the same 'ccgroup' name in the
+@code{var_stream_map} string. If @code{var_stream_map} is not set, then the
+first available ccgroup in @code{cc_stream_map} is mapped to the output variant
+stream. The examples for these two use cases are given below.
+
+@example
+ffmpeg -re -i in.ts -b:v 1000k -b:a 64k -a53cc 1 -f hls \
+  -cc_stream_map "ccgroup:cc,instreamid:CC1,language:en" \
+  -master_pl_name master.m3u8 \
+  http://example.com/live/out.m3u8
+@end example
+This example adds @code{#EXT-X-MEDIA} tag with @code{TYPE=CLOSED-CAPTIONS} in
+the master playlist with group name 'cc', langauge 'en' (english) and
+INSTREAM-ID 'CC1'. Also, it adds @code{CLOSED-CAPTIONS} attribute with group
+name 'cc' for the output variant stream.
+@example
+ffmpeg -re -i in.ts -b:v:0 1000k -b:v:1 256k -b:a:0 64k -b:a:1 32k \
+  -a53cc:0 1 -a53cc:1 1\
+  -map 0:v -map 0:a -map 0:v -map 0:a -f hls \
+  -cc_stream_map "ccgroup:cc,instreamid:CC1,language:en ccgroup:cc,instreamid:CC2,language:sp" \
+  -var_stream_map "v:0,a:0,ccgroup:cc v:1,a:1,ccgroup:cc" \
+  -master_pl_name master.m3u8 \
+  http://example.com/live/out_%v.m3u8
+@end example
+This example adds two @code{#EXT-X-MEDIA} tags with @code{TYPE=CLOSED-CAPTIONS} in
+the master playlist for the INSTREAM-IDs 'CC1' and 'CC2'. Also, it adds
+@code{CLOSED-CAPTIONS} attribute with group name 'cc' for the two output variant
+streams.
+
 @item master_pl_name
 Create HLS master playlist with the given name.
 

libavformat/dashenc.c

@@ -820,7 +820,7 @@ static int write_manifest(AVFormatContext *s, int final)
                 stream_bitrate += max_audio_bitrate;
             }
             get_hls_playlist_name(playlist_file, sizeof(playlist_file), NULL, i);
-            ff_hls_write_stream_info(st, out, stream_bitrate, playlist_file, agroup, NULL);
+            ff_hls_write_stream_info(st, out, stream_bitrate, playlist_file, agroup, NULL, NULL);
         }
         avio_close(out);
         if (use_rename)

libavformat/hlsplaylist.c

@@ -47,7 +47,8 @@ void ff_hls_write_audio_rendition(AVIOContext *out, char *agroup,
 
 void ff_hls_write_stream_info(AVStream *st, AVIOContext *out,
                               int bandwidth, char *filename, char *agroup,
-                              char *codecs) {
+                              char *codecs, char *ccgroup) {
+
     if (!out || !filename)
         return;
 
@@ -65,6 +66,8 @@ void ff_hls_write_stream_info(AVStream *st, AVIOContext *out,
         avio_printf(out, ",CODECS=\"%s\"", codecs);
     if (agroup && strlen(agroup) > 0)
         avio_printf(out, ",AUDIO=\"group_%s\"", agroup);
+    if (ccgroup && strlen(ccgroup) > 0)
+        avio_printf(out, ",CLOSED-CAPTIONS=\"%s\"", ccgroup);
     avio_printf(out, "\n%s\n\n", filename);
 }
 

libavformat/hlsplaylist.h

@@ -41,7 +41,7 @@ void ff_hls_write_audio_rendition(AVIOContext *out, char *agroup,
                                   char *filename, int name_id, int is_default);
 void ff_hls_write_stream_info(AVStream *st, AVIOContext *out,
                               int bandwidth, char *filename, char *agroup,
-                              char *codecs);
+                              char *codecs, char *ccgroup);
 void ff_hls_write_playlist_header(AVIOContext *out, int version, int allowcache,
                                   int target_duration, int64_t sequence,
                                   uint32_t playlist_type);