From 2f2d4a829d30a8dfc6084b347bb597ac994d6dda Mon Sep 17 00:00:00 2001
From: Philippe Symons <philippe.symons@gmail.com>
Date: Thu, 15 Nov 2018 00:20:17 +0100
Subject: [PATCH] [HLS] Add LANGUAGE attribute to #EXT-X-MEDIA tag for 
 audio-only variant streams.

Signed-off-by: Philippe Symons <philippe.symons@gmail.com>
---
 libavformat/dashenc.c     |  2 +-
 libavformat/hlsenc.c      | 21 +++++++++++++++++++--
 libavformat/hlsplaylist.c |  6 +++++-
 libavformat/hlsplaylist.h |  2 +-
 4 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index d151921175..17465c1917 100644
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -898,7 +898,7 @@ static int write_manifest(AVFormatContext *s, int final)
             if (st->codecpar->codec_type != AVMEDIA_TYPE_AUDIO)
                 continue;
             get_hls_playlist_name(playlist_file, sizeof(playlist_file), NULL, i);
-            ff_hls_write_audio_rendition(c->m3u8_out, (char *)audio_group,
+            ff_hls_write_audio_rendition(c->m3u8_out, (char *)audio_group, NULL, 
                                          playlist_file, i, is_default);
             max_audio_bitrate = FFMAX(st->codecpar->bit_rate +
                                       os->muxer_overhead, max_audio_bitrate);
diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
index e0048aa9d8..fb77aa9ba8 100644
--- a/libavformat/hlsenc.c
+++ b/libavformat/hlsenc.c
@@ -1205,7 +1205,6 @@ static int create_master_playlist(AVFormatContext *s,
     }
 
     set_http_options(s, &options, hls);
-
     ret = hlsenc_io_open(s, &hls->m3u8_out, hls->master_m3u8_url, &options);
     av_dict_free(&options);
     if (ret < 0) {
@@ -1228,12 +1227,30 @@ static int create_master_playlist(AVFormatContext *s,
 
     /* For audio only variant streams add #EXT-X-MEDIA tag with attributes*/
     for (i = 0; i < hls->nb_varstreams; i++) {
+        AVFormatContext* var_context;
+        char* language = NULL;
+
         vs = &(hls->var_streams[i]);
+        var_context = vs->avf;
 
         if (vs->has_video || vs->has_subtitle || !vs->agroup)
             continue;
 
         m3u8_name_size = strlen(vs->m3u8_name) + 1;
+        
+        /*
+         * Try to obtain the language code of the audio stream.
+         * -if available- it will be used to write the LANGUAGE
+         * attribute in the #EXT-X-MEDIA tag
+         */
+        if(var_context && var_context->nb_streams > 0) {
+            AVDictionary* meta_dict = vs->streams[0]->metadata;
+            AVDictionaryEntry *langEntry = av_dict_get(meta_dict, "language", NULL, 0);
+            if(langEntry) {
+                language = langEntry->value;
+            }
+        }
+
         m3u8_rel_name = av_malloc(m3u8_name_size);
         if (!m3u8_rel_name) {
             ret = AVERROR(ENOMEM);
@@ -1247,7 +1264,7 @@ static int create_master_playlist(AVFormatContext *s,
             goto fail;
         }
 
-        ff_hls_write_audio_rendition(hls->m3u8_out, vs->agroup, m3u8_rel_name, 0, 1);
+        ff_hls_write_audio_rendition(hls->m3u8_out, vs->agroup, language, m3u8_rel_name, 0, 1);
 
         av_freep(&m3u8_rel_name);
     }
diff --git a/libavformat/hlsplaylist.c b/libavformat/hlsplaylist.c
index efcbff0009..42c7cf5727 100644
--- a/libavformat/hlsplaylist.c
+++ b/libavformat/hlsplaylist.c
@@ -35,12 +35,16 @@ void ff_hls_write_playlist_version(AVIOContext *out, int version) {
     avio_printf(out, "#EXT-X-VERSION:%d\n", version);
 }
 
-void ff_hls_write_audio_rendition(AVIOContext *out, char *agroup,
+void ff_hls_write_audio_rendition(AVIOContext *out, char *agroup, char* language, 
                                   char *filename, int name_id, int is_default) {
     if (!out || !agroup || !filename)
         return;
 
     avio_printf(out, "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"group_%s\"", agroup);
+
+    if(language)
+        avio_printf(out, ",LANGUAGE=\"%s\"", language);
+
     avio_printf(out, ",NAME=\"audio_%d\",DEFAULT=%s,URI=\"%s\"\n", name_id,
                      is_default ? "YES" : "NO", filename);
 }
diff --git a/libavformat/hlsplaylist.h b/libavformat/hlsplaylist.h
index 5054b01c8f..faf1ccdd02 100644
--- a/libavformat/hlsplaylist.h
+++ b/libavformat/hlsplaylist.h
@@ -37,7 +37,7 @@ typedef enum {
 } PlaylistType;
 
 void ff_hls_write_playlist_version(AVIOContext *out, int version);
-void ff_hls_write_audio_rendition(AVIOContext *out, char *agroup,
+void ff_hls_write_audio_rendition(AVIOContext *out, char *agroup, char* language, 
                                   char *filename, int name_id, int is_default);
 void ff_hls_write_stream_info(AVStream *st, AVIOContext *out,
                               int bandwidth, char *filename, char *agroup,
-- 
2.17.1

