[nrf fromtree] Bluetooth: BAP: Add support for transparent coding format

Add support for controlling whether the local controller
should transcode, or whether it will be done by another
module (e.g. the host).

By default when using the macros,
controller transcoding will be disabled.

Signed-off-by: Emil Gydesen <[email protected]>
(cherry picked from commit 1faa5a2)
Signed-off-by: Jui-Chou Chung <[email protected]>

Author: Thalley

Diff for: include/zephyr/bluetooth/audio/audio.h

@@ -209,6 +209,7 @@ enum bt_audio_metadata_type {
 	((struct bt_audio_codec_cfg){                                                              \
 		/* Use HCI data path as default, can be overwritten by application */              \
 		.path_id = BT_ISO_DATA_PATH_HCI,                                                   \
+		.ctlr_transcode = false,                                                           \
 		.id = _id,                                                                         \
 		.cid = _cid,                                                                       \
 		.vid = _vid,                                                                       \
@@ -231,6 +232,7 @@ enum bt_audio_metadata_type {
 	((struct bt_audio_codec_cap){                                                              \
 		/* Use HCI data path as default, can be overwritten by application */              \
 		.path_id = BT_ISO_DATA_PATH_HCI,                                                   \
+		.ctlr_transcode = false,                                                           \
 		.id = (_id),                                                                       \
 		.cid = (_cid),                                                                     \
 		.vid = (_vid),                                                                     \
@@ -316,6 +318,12 @@ struct bt_audio_codec_cap {
 	 * vendor specific ID.
 	 */
 	uint8_t path_id;
+	/** Whether or not the local controller should transcode
+	 *
+	 * This effectively sets the coding format for the ISO data path to @ref
+	 * BT_HCI_CODING_FORMAT_TRANSPARENT if false, else uses the @ref bt_audio_codec_cfg.id.
+	 */
+	bool ctlr_transcode;
 	/** Codec ID */
 	uint8_t id;
 	/** Codec Company ID */
@@ -344,6 +352,12 @@ struct bt_audio_codec_cfg {
 	 * vendor specific ID.
 	 */
 	uint8_t path_id;
+	/** Whether or not the local controller should transcode
+	 *
+	 * This effectively sets the coding format for the ISO data path to @ref
+	 * BT_HCI_CODING_FORMAT_TRANSPARENT if false, else uses the @ref bt_audio_codec_cfg.id.
+	 */
+	bool ctlr_transcode;
 	/** Codec ID */
 	uint8_t  id;
 	/** Codec Company ID */

Diff for: subsys/bluetooth/audio/bap_stream.c

@@ -35,12 +35,22 @@ void bt_audio_codec_cfg_to_iso_path(struct bt_iso_chan_path *path,
 				    struct bt_audio_codec_cfg *codec_cfg)
 {
 	path->pid = codec_cfg->path_id;
-	path->format = codec_cfg->id;
-	path->cid = codec_cfg->cid;
-	path->vid = codec_cfg->vid;
-	path->delay = 0; /* TODO: Add to bt_audio_codec_cfg? Use presentation delay? */
-	path->cc_len = codec_cfg->data_len;
-	path->cc = codec_cfg->data;
+
+	if (codec_cfg->ctlr_transcode) {
+		path->format = codec_cfg->id;
+		path->cid = codec_cfg->cid;
+		path->vid = codec_cfg->vid;
+		path->delay = 0;
+		path->cc_len = codec_cfg->data_len;
+		path->cc = codec_cfg->data;
+	} else {
+		path->format = BT_HCI_CODING_FORMAT_TRANSPARENT;
+		path->cid = 0;
+		path->vid = 0;
+		path->delay = 0;
+		path->cc_len = 0;
+		path->cc = NULL;
+	}
 }
 
 #if defined(CONFIG_BT_BAP_UNICAST_CLIENT) || defined(CONFIG_BT_BAP_BROADCAST_SOURCE) ||            \