ast_format: Adds an identifier for interleaved audio formats to the ast_format

Adds an identifier (with a getter and setter) to detect channels with
interleaved audio.
This is needed by the binaural bridge_softmix patch (ASTERISK-26292) and
was already discussed here:
http://lists.digium.com/pipermail/asterisk-dev/2016-October/075900.html
The identifier can be set during fmtp parsing (to be seen in the
res_format_attr_opus.c change).

ASTERISK-26292

Change-Id: I359801cc5f98c35671c48dabc81a7f4ee1183d63

include/asterisk/format.h

@@ -298,6 +298,24 @@ void ast_format_set_attribute_data(struct ast_format *format, void *attribute_da
  */
 const char *ast_format_get_name(const struct ast_format *format);
 
+/*!
+ * \brief Get the channel count on a format
+ *
+ * \param The media format
+ *
+ * \return Currently set channel count
+ */
+unsigned int ast_format_get_channel_count(const struct ast_format *format);
+
+/*!
+ * \brief Set the channel count on a format
+ *
+ * \param format The media format
+ * \param channel_count The number of audio channels used
+ *
+ */
+void ast_format_set_channel_count(struct ast_format *format, unsigned int channel_count);
+
 /*!
  * \brief Get the codec associated with a format
  *

main/format.c

@@ -49,6 +49,8 @@ struct ast_format {
 	void *attribute_data;
 	/*! \brief Pointer to the optional format interface */
 	const struct ast_format_interface *interface;
+	/*! \brief The number if audio channels used, if more than one an interleaved format is required */
+	unsigned int channel_count;
 };
 
 /*! \brief Structure used when registering a format interface */
@@ -175,6 +177,16 @@ void ast_format_set_attribute_data(struct ast_format *format, void *attribute_da
 	format->attribute_data = attribute_data;
 }
 
+unsigned int ast_format_get_channel_count(const struct ast_format *format)
+{
+	return format->channel_count;
+}
+
+void ast_format_set_channel_count(struct ast_format *format, unsigned int channel_count)
+{
+	format->channel_count = channel_count;
+}
+
 /*! \brief Destructor for media formats */
 static void format_destroy(void *obj)
 {
@@ -199,6 +211,7 @@ struct ast_format *ast_format_create_named(const char *format_name, struct ast_c
 	}
 	format->name = format_name;
 	format->codec = ao2_bump(codec);
+	format->channel_count = 1;
 
 	format_interface = ao2_find(interfaces, codec->name, OBJ_SEARCH_KEY);
 	if (format_interface) {

res/res_format_attr_opus.c

@@ -94,6 +94,7 @@ static int opus_clone(const struct ast_format *src, struct ast_format *dst)
 	ao2_bump(attr->data);
 
 	ast_format_set_attribute_data(dst, attr);
+	ast_format_set_channel_count(dst, ast_format_get_channel_count(src));
 
 	return 0;
 }
@@ -145,6 +146,9 @@ static struct ast_format *opus_parse_sdp_fmtp(const struct ast_format *format, c
 	sdp_fmtp_get(attributes, CODEC_OPUS_ATTR_PTIME, &attr->ptime);
 	sdp_fmtp_get(attributes, CODEC_OPUS_ATTR_MAX_AVERAGE_BITRATE, &attr->maxbitrate);
 	sdp_fmtp_get(attributes, CODEC_OPUS_ATTR_STEREO, &attr->stereo);
+	if (attr->stereo) {
+		ast_format_set_channel_count(cloned, 2);
+	}
 	sdp_fmtp_get(attributes, CODEC_OPUS_ATTR_SPROP_STEREO, &attr->spropstereo);
 	sdp_fmtp_get(attributes, CODEC_OPUS_ATTR_CBR, &attr->cbr);
 	sdp_fmtp_get(attributes, CODEC_OPUS_ATTR_FEC, &attr->fec);
@@ -236,6 +240,10 @@ static struct ast_format *opus_getjoint(const struct ast_format *format1, const
 	if (!jointformat) {
 		return NULL;
 	}
+
+	if (ast_format_get_channel_count(format1) == 2 || ast_format_get_channel_count(format2) == 2) {
+		ast_format_set_channel_count(jointformat, 2);
+	}
 	attr_res = ast_format_get_attribute_data(jointformat);
 
 	attr_res->dtx = attr1->dtx || attr2->dtx ? 1 : 0;