Parse the audio_type field of the iso639_language_descriptor - this indicates if the audio stream contains audio description for the hard of hearing. Use this value when regenerating the PMT for the passthrough muxer, and also include it in the HTSP stream description messages.

src/htsp_server.c

@@ -2421,6 +2421,7 @@ htsp_subscription_start(htsp_subscription_t *hs, const streaming_start_t *ss)
 
     if (SCT_ISAUDIO(ssc->ssc_type))
     {
+      htsmsg_add_u32(c, "audio_type", ssc->ssc_audio_type);
       if (ssc->ssc_channels)
         htsmsg_add_u32(c, "channels", ssc->ssc_channels);
       if (ssc->ssc_sri)

src/psi.c

@@ -172,16 +172,17 @@ psi_build_pat(service_t *t, uint8_t *buf, int maxlen, int pmtpid)
 #define PMT_UPDATE_PCR                0x1
 #define PMT_UPDATE_NEW_STREAM         0x2
 #define PMT_UPDATE_LANGUAGE           0x4
-#define PMT_UPDATE_FRAME_DURATION     0x8
-#define PMT_UPDATE_COMPOSITION_ID     0x10
-#define PMT_UPDATE_ANCILLARY_ID       0x20
-#define PMT_UPDATE_STREAM_DELETED     0x40
-#define PMT_UPDATE_NEW_CA_STREAM      0x80
-#define PMT_UPDATE_NEW_CAID           0x100
-#define PMT_UPDATE_CA_PROVIDER_CHANGE 0x200
-#define PMT_UPDATE_PARENT_PID         0x400
-#define PMT_UPDATE_CAID_DELETED       0x800
-#define PMT_REORDERED                 0x1000
+#define PMT_UPDATE_AUDIO_TYPE         0x8
+#define PMT_UPDATE_FRAME_DURATION     0x10
+#define PMT_UPDATE_COMPOSITION_ID     0x20
+#define PMT_UPDATE_ANCILLARY_ID       0x40
+#define PMT_UPDATE_STREAM_DELETED     0x80
+#define PMT_UPDATE_NEW_CA_STREAM      0x100
+#define PMT_UPDATE_NEW_CAID           0x200
+#define PMT_UPDATE_CA_PROVIDER_CHANGE 0x400
+#define PMT_UPDATE_PARENT_PID         0x800
+#define PMT_UPDATE_CAID_DELETED       0x1000
+#define PMT_REORDERED                 0x2000
 
 /**
  * Add a CA descriptor
@@ -397,6 +398,7 @@ psi_parse_pmt(service_t *t, const uint8_t *ptr, int len, int chksvcid,
   int position = 0;
   int tt_position = 1000;
   const char *lang = NULL;
+  uint8_t audio_type = 0;
 
   caid_t *c, *cn;
 
@@ -529,6 +531,7 @@ psi_parse_pmt(service_t *t, const uint8_t *ptr, int len, int chksvcid,
 
       case DVB_DESC_LANGUAGE:
         lang = lang_code_get2((const char*)ptr, 3);
+        audio_type = ptr[3];
 	      break;
 
       case DVB_DESC_TELETEXT:
@@ -601,6 +604,11 @@ psi_parse_pmt(service_t *t, const uint8_t *ptr, int len, int chksvcid,
         memcpy(st->es_lang, lang, 4);
       }
 
+      if(st->es_audio_type != audio_type) {
+        update |= PMT_UPDATE_AUDIO_TYPE;
+        st->es_audio_type = audio_type;
+      }
+
       if(composition_id != -1 && st->es_composition_id != composition_id) {
 	st->es_composition_id = composition_id;
 	update |= PMT_UPDATE_COMPOSITION_ID;
@@ -756,7 +764,7 @@ psi_build_pmt(const streaming_start_t *ss, uint8_t *buf0, int maxlen,
       buf[0] = DVB_DESC_LANGUAGE;
       buf[1] = 4;
       memcpy(&buf[2],ssc->ssc_lang,3);
-      buf[5] = 0; /* Main audio */
+      buf[5] = ssc->ssc_audio_type;
       dlen = 6;
       break;
     case SCT_DVBSUB:

src/service.c

@@ -908,6 +908,7 @@ service_build_stream_start(service_t *t)
     ssc->ssc_type  = st->es_type;
 
     memcpy(ssc->ssc_lang, st->es_lang, 4);
+    ssc->ssc_audio_type = st->es_audio_type;
     ssc->ssc_composition_id = st->es_composition_id;
     ssc->ssc_ancillary_id = st->es_ancillary_id;
     ssc->ssc_pid = st->es_pid;

src/service.h

@@ -82,6 +82,8 @@ typedef struct elementary_stream {
   uint16_t es_aspect_den;
 
   char es_lang[4];           /* ISO 639 2B 3-letter language code */
+  uint8_t es_audio_type;     /* Audio type */
+
   uint16_t es_composition_id;
   uint16_t es_ancillary_id;
 

src/streaming.h

@@ -27,6 +27,7 @@ typedef struct streaming_start_component {
   int ssc_index;
   int ssc_type;
   char ssc_lang[4];
+  uint8_t ssc_audio_type;
   uint16_t ssc_composition_id;
   uint16_t ssc_ancillary_id;
   uint16_t ssc_pid;