applications: nrf5340_audio: Integrate sample rate converter

- Have fixed system sample rate
- Convert frames based on config from LE Audio

Signed-off-by: Andreas Vibeto <andreas.vibeto@nordicsemi.no>
Signed-off-by: Alexander Svensen <alexander.svensen@nordicsemi.no>

Author: andvib

applications/nrf5340_audio/broadcast_sink/main.c

@@ -222,7 +222,7 @@ static void le_audio_msg_sub_thread(void)
 			break;
 
 		case LE_AUDIO_EVT_CONFIG_RECEIVED:
-			LOG_DBG("Config received");
+			LOG_DBG("LE audio config received");
 
 			ret = broadcast_sink_config_get(&bitrate_bps, &sampling_rate_hz,
 							&pres_delay_us);
@@ -231,8 +231,12 @@ static void le_audio_msg_sub_thread(void)
 				break;
 			}
 
-			LOG_DBG("Sampling rate: %d Hz", sampling_rate_hz);
-			LOG_DBG("Bitrate: %d bps", bitrate_bps);
+			LOG_DBG("\tSampling rate: %d Hz", sampling_rate_hz);
+			LOG_DBG("\tBitrate (compressed): %d bps", bitrate_bps);
+
+			ret = audio_system_config_set(VALUE_NOT_SET, VALUE_NOT_SET,
+						      sampling_rate_hz);
+			ERR_CHK(ret);
 
 			ret = audio_datapath_pres_delay_us_set(pres_delay_us);
 			if (ret) {

applications/nrf5340_audio/broadcast_source/main.c

@@ -6,6 +6,7 @@
 
 #include "streamctrl.h"
 
+#include <zephyr/bluetooth/audio/audio.h>
 #include <zephyr/kernel.h>
 #include <zephyr/zbus/zbus.h>
 
@@ -337,6 +338,11 @@ int main(void)
 	ret = broadcast_source_enable();
 	ERR_CHK_MSG(ret, "Failed to enable broadcaster");
 
+	ret = audio_system_config_set(
+		bt_audio_codec_cfg_freq_to_freq_hz(CONFIG_BT_AUDIO_PREF_SAMPLE_RATE_VALUE),
+		CONFIG_BT_AUDIO_BITRATE_BROADCAST_SRC, VALUE_NOT_SET);
+	ERR_CHK_MSG(ret, "Failed to set sample- and bitrate");
+
 	broadcast_source_adv_get(&ext_adv, &ext_adv_size, &per_adv, &per_adv_size);
 
 	ret = bt_mgmt_adv_start(ext_adv, ext_adv_size, per_adv, per_adv_size, false);

applications/nrf5340_audio/prj.conf

@@ -7,6 +7,9 @@
 # nRF5340 Audio
 CONFIG_NRF5340_AUDIO=y
 
+CONFIG_SAMPLE_RATE_CONVERTER=y
+CONFIG_SAMPLE_RATE_CONVERTER_FILTER_SIMPLE=y
+
 # General
 CONFIG_DEBUG=y
 CONFIG_DEBUG_INFO=y

applications/nrf5340_audio/prj_release.conf

@@ -7,6 +7,9 @@
 # nRF5340 Audio
 CONFIG_NRF5340_AUDIO=y
 
+CONFIG_SAMPLE_RATE_CONVERTER=y
+CONFIG_SAMPLE_RATE_CONVERTER_FILTER_SIMPLE=y
+
 # General
 CONFIG_DEBUG=n
 CONFIG_ASSERT=n

applications/nrf5340_audio/src/audio/Kconfig

@@ -43,13 +43,12 @@ config AUDIO_MAX_PRES_DLY_US
 	help
 	  The maximum presentation delay in micro seconds.
 
-choice AUDIO_SAMPLE_RATE
-	prompt "Audio sample rate"
-	default AUDIO_SAMPLE_RATE_16000_HZ if BT_BAP_BROADCAST_16_2_1 || BT_BAP_BROADCAST_16_2_2 || BT_BAP_UNICAST_16_2_1
-	default AUDIO_SAMPLE_RATE_24000_HZ if BT_BAP_BROADCAST_24_2_1 || BT_BAP_BROADCAST_24_2_2 || BT_BAP_UNICAST_24_2_1
+choice AUDIO_SYSTEM_SAMPLE_RATE
+	prompt "System audio sample rate"
 	default AUDIO_SAMPLE_RATE_48000_HZ
 	help
-	  This will be selected based on the BAP settings.
+	  This configuration reflects the system sample rate, but the audio data may be resampled to
+	  another sample rate before encoding, and after decoding.
 
 config AUDIO_SAMPLE_RATE_16000_HZ
 	bool "16 kHz"
@@ -213,7 +212,7 @@ visible if SW_CODEC_LC3
 
 config LC3_BITRATE_MAX
 	int "Max bitrate for LC3"
-	default 124000
+	default 96000
 
 config LC3_BITRATE_MIN
 	int "Min bitrate for LC3"
@@ -343,13 +342,13 @@ menu "Stack sizes"
 
 config ENCODER_STACK_SIZE
 	int "Stack size for encoder thread"
-	default 7500 if AUDIO_BIT_DEPTH_16
-	default 11264 if AUDIO_BIT_DEPTH_32
+	default 11000 if AUDIO_BIT_DEPTH_16
+	default 21400 if AUDIO_BIT_DEPTH_32
 
 config AUDIO_DATAPATH_STACK_SIZE
 	int "Stack size for audio datapath thread"
-	default 4096 if AUDIO_BIT_DEPTH_16
-	default 8192 if AUDIO_BIT_DEPTH_32
+	default 7600 if AUDIO_BIT_DEPTH_16
+	default 14700 if AUDIO_BIT_DEPTH_32
 
 config BUTTON_MSG_SUB_STACK_SIZE
 	int "Stack size for button subscriber"

applications/nrf5340_audio/src/audio/audio_datapath.c

@@ -980,7 +980,8 @@ void audio_datapath_stream_out(const uint8_t *buf, size_t size, uint32_t sdu_ref
 	}
 
 	if (pcm_size != (BLK_STEREO_SIZE_OCTETS * NUM_BLKS_IN_FRAME)) {
-		LOG_WRN("Decoded audio has wrong size");
+		LOG_WRN("Decoded audio has wrong size: %d. Expected: %d", pcm_size,
+			(BLK_STEREO_SIZE_OCTETS * NUM_BLKS_IN_FRAME));
 		/* Discard frame */
 		return;
 	}

applications/nrf5340_audio/src/audio/audio_system.c

@@ -50,6 +50,15 @@ static struct sw_codec_config sw_codec_cfg;
 static int16_t test_tone_buf[CONFIG_AUDIO_SAMPLE_RATE_HZ / 1000];
 static size_t test_tone_size;
 
+static bool sample_rate_valid(uint32_t sample_rate_hz)
+{
+	if (sample_rate_hz == 16000 || sample_rate_hz == 24000 || sample_rate_hz == 48000) {
+		return true;
+	}
+
+	return false;
+}
+
 static void audio_gateway_configure(void)
 {
 	if (IS_ENABLED(CONFIG_SW_CODEC_LC3)) {
@@ -64,12 +73,6 @@ static void audio_gateway_configure(void)
 	sw_codec_cfg.decoder.channel_mode = SW_CODEC_MONO;
 #endif /* (CONFIG_STREAM_BIDIRECTIONAL) */
 
-	if (IS_ENABLED(CONFIG_SW_CODEC_LC3)) {
-		sw_codec_cfg.encoder.bitrate = CONFIG_LC3_BITRATE;
-	} else {
-		ERR_CHK_MSG(-EINVAL, "No codec selected");
-	}
-
 	if (IS_ENABLED(CONFIG_MONO_TO_ALL_RECEIVERS)) {
 		sw_codec_cfg.encoder.num_ch = 1;
 	} else {
@@ -93,12 +96,6 @@ static void audio_headset_configure(void)
 	sw_codec_cfg.encoder.enabled = true;
 	sw_codec_cfg.encoder.num_ch = 1;
 	sw_codec_cfg.encoder.channel_mode = SW_CODEC_MONO;
-
-	if (IS_ENABLED(CONFIG_SW_CODEC_LC3)) {
-		sw_codec_cfg.encoder.bitrate = CONFIG_LC3_BITRATE;
-	} else {
-		ERR_CHK_MSG(-EINVAL, "No codec selected");
-	}
 #endif /* (CONFIG_STREAM_BIDIRECTIONAL) */
 
 	sw_codec_cfg.decoder.num_ch = 1;
@@ -259,6 +256,30 @@ int audio_system_encode_test_tone_step(void)
 	return 0;
 }
 
+int audio_system_config_set(uint32_t encoder_sample_rate_hz, uint32_t encoder_bitrate,
+			    uint32_t decoder_sample_rate_hz)
+{
+	if (sample_rate_valid(encoder_sample_rate_hz)) {
+		sw_codec_cfg.encoder.sample_rate_hz = encoder_sample_rate_hz;
+	} else if (encoder_sample_rate_hz) {
+		LOG_ERR("%d is not a valid sample rate", encoder_sample_rate_hz);
+		return -EINVAL;
+	}
+
+	if (sample_rate_valid(decoder_sample_rate_hz)) {
+		sw_codec_cfg.decoder.sample_rate_hz = decoder_sample_rate_hz;
+	} else if (decoder_sample_rate_hz) {
+		LOG_ERR("%d is not a valid sample rate", decoder_sample_rate_hz);
+		return -EINVAL;
+	}
+
+	if (encoder_bitrate) {
+		sw_codec_cfg.encoder.bitrate = encoder_bitrate;
+	}
+
+	return 0;
+}
+
 /* This function is only used on gateway using USB as audio source and bidirectional stream */
 int audio_system_decode(void const *const encoded_data, size_t encoded_data_size, bool bad_frame)
 {

applications/nrf5340_audio/src/audio/audio_system.h

@@ -11,6 +11,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#define VALUE_NOT_SET 0
+
 /**
  * @brief	Start the execution of the encoder thread.
  */
@@ -46,6 +48,21 @@ int audio_system_encode_test_tone_set(uint32_t freq);
  */
 int audio_system_encode_test_tone_step(void);
 
+/**
+ * @brief	Set the sample rates for the encoder and the decoder, and the bit rate for encoder.
+ *
+ * @note	If any of the values are 0, the corresponding configuration will not be set.
+ *
+ * @param[in]	encoder_sample_rate_hz	Sample rate to be used by the encoder; can be 0.
+ * @param[in]	encoder_bitrate		Bit rate to be used by the encoder (bps); can be 0.
+ * @param[in]	decoder_sample_rate_hz	Sample rate to be used by the decoder; can be 0.
+ *
+ * @retval	-EINVAL	Invalid sample rate given.
+ * @retval	0	On success.
+ */
+int audio_system_config_set(uint32_t encoder_sample_rate_hz, uint32_t encoder_bitrate,
+			    uint32_t decoder_sample_rate_hz);
+
 /**
  * @brief	Decode data and then add it to TX FIFO buffer.
  *