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samples: Bluetooth: Broadcast sink: Add proper parsing decoding of LC3 data

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The sample assumed that the broadcast audio was always a single
frame per block. This commit improves the validation of the
codec configuration from the broadcast source, and properly
decodes the SDU using the configuration values.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>
This commit is contained in:
Emil Gydesen 2024-02-21 12:59:06 +01:00 • committed by Henrik Brix Andersen
commit 53cca3ea4e
1 changed files with 90 additions and 22 deletions
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90
samples/bluetooth/broadcast_audio_sink/src/main.c
View file

@ -93,6 +93,12 @@ static struct broadcast_sink_stream {
#if defined(CONFIG_LIBLC3)
struct net_buf *in_buf;
struct k_work_delayable lc3_decode_work;
/* LC3 config values */
enum bt_audio_location chan_allocation;
uint16_t lc3_octets_per_frame;
uint8_t lc3_frames_blocks_per_sdu;
/* Internal lock for protecting net_buf from multiple access */
struct k_mutex lc3_decoder_mutex;
lc3_decoder_t lc3_decoder;
@ -131,7 +137,6 @@ static void add_to_usb_ring_buf(const int16_t audio_buf[LC3_MAX_NUM_SAMPLES_STER
#endif /* defined(CONFIG_USB_DEVICE_AUDIO) */
#if defined(CONFIG_LIBLC3)
static int frames_per_sdu;
static K_SEM_DEFINE(lc3_decoder_sem, 0, 1);
static bool do_lc3_decode(struct broadcast_sink_stream *sink_stream,
@ -174,11 +179,29 @@ static void lc3_decoder_thread(void *arg1, void *arg2, void *arg3)
}
}
static size_t get_chan_cnt(enum bt_audio_location chan_allocation)
{
size_t cnt = 0U;
if (chan_allocation == BT_AUDIO_LOCATION_MONO_AUDIO) {
return 1;
}
while (chan_allocation != 0) {
cnt += chan_allocation & 1U;
chan_allocation >>= 1;
}
return cnt;
}
/** Decode LC3 data on a stream and returns true if successful */
static bool do_lc3_decode(struct broadcast_sink_stream *sink_stream,
int16_t audio_buf[LC3_MAX_NUM_SAMPLES_STEREO])
{
uint16_t octets_per_frame;
const uint8_t frames_blocks_per_sdu = sink_stream->lc3_frames_blocks_per_sdu;
const uint16_t octets_per_frame = sink_stream->lc3_octets_per_frame;
uint16_t frames_per_block;
struct net_buf *buf;
k_mutex_lock(&sink_stream->lc3_decoder_mutex, K_FOREVER);
@ -194,17 +217,18 @@ static bool do_lc3_decode(struct broadcast_sink_stream *sink_stream,
sink_stream->in_buf = NULL;
k_mutex_unlock(&sink_stream->lc3_decoder_mutex);
octets_per_frame = buf->len / frames_per_sdu;
if (buf->len != (octets_per_frame * frames_per_sdu)) {
printk("Expected %u frames of size %u, but length is %u\n", frames_per_sdu,
octets_per_frame, buf->len);
frames_per_block = get_chan_cnt(sink_stream->chan_allocation);
if (buf->len != (frames_per_block * octets_per_frame * frames_blocks_per_sdu)) {
printk("Expected %u frame blocks with %u frames of size %u, but length is %u\n",
frames_blocks_per_sdu, frames_per_block, octets_per_frame, buf->len);
net_buf_unref(buf);
return false;
}
for (int i = 0; i < frames_per_sdu; i++) {
for (uint8_t i = 0U; i < frames_blocks_per_sdu; i++) {
for (uint16_t j = 0U; j < frames_per_block; j++) {
const void *data = net_buf_pull_mem(buf, octets_per_frame);
int err;
@ -221,6 +245,7 @@ static bool do_lc3_decode(struct broadcast_sink_stream *sink_stream,
return false;
}
}
}
net_buf_unref(buf);
@ -229,9 +254,11 @@ static bool do_lc3_decode(struct broadcast_sink_stream *sink_stream,
static int lc3_enable(struct broadcast_sink_stream *sink_stream)
{
int ret;
int freq_hz;
size_t chan_alloc_bit_cnt;
size_t sdu_size_required;
int frame_duration_us;
int freq_hz;
int ret;
printk("Enable: stream with codec %p\n", sink_stream->stream.codec_cfg);
@ -251,8 +278,49 @@ static int lc3_enable(struct broadcast_sink_stream *sink_stream)
return ret;
}
frames_per_sdu = bt_audio_codec_cfg_get_frame_blocks_per_sdu(sink_stream->stream.codec_cfg,
true);
ret = bt_audio_codec_cfg_get_chan_allocation(sink_stream->stream.codec_cfg,
&sink_stream->chan_allocation);
if (ret != 0) {
printk("Error: Channel allocation not set, invalid configuration for LC3");
return ret;
}
ret = bt_audio_codec_cfg_get_octets_per_frame(sink_stream->stream.codec_cfg);
if (ret > 0) {
sink_stream->lc3_octets_per_frame = (uint16_t)ret;
} else {
printk("Error: Octets per frame not set, invalid configuration for LC3");
return ret;
}
ret = bt_audio_codec_cfg_get_frame_blocks_per_sdu(sink_stream->stream.codec_cfg, true);
if (ret > 0) {
sink_stream->lc3_frames_blocks_per_sdu = (uint8_t)ret;
} else {
printk("Error: Frame blocks per SDU not set, invalid configuration for LC3");
return ret;
}
/* An SDU can consist of X frame blocks, each with Y frames (one per channel) of size Z in
* them. The minimum SDU size required for this is X * Y * Z.
*/
chan_alloc_bit_cnt = get_chan_cnt(sink_stream->chan_allocation);
sdu_size_required = chan_alloc_bit_cnt * sink_stream->lc3_octets_per_frame *
sink_stream->lc3_frames_blocks_per_sdu;
if (sdu_size_required < sink_stream->stream.qos->sdu) {
printk("With %zu channels and %u octets per frame and %u frames per block, SDUs "
"shall be at minimum %zu, but the stream has been configured for %u",
chan_alloc_bit_cnt, sink_stream->lc3_octets_per_frame,
sink_stream->lc3_frames_blocks_per_sdu, sdu_size_required,
sink_stream->stream.qos->sdu);
return -EINVAL;
}
printk("Enabling LC3 decoder with frame duration %uus, frequency %uHz and with channel "
"allocation 0x%08X, %u octets per frame and %u frame blocks per SDU\n",
frame_duration_us, freq_hz, sink_stream->chan_allocation,
sink_stream->lc3_octets_per_frame, sink_stream->lc3_frames_blocks_per_sdu);
#if defined(CONFIG_USB_DEVICE_AUDIO)
sink_stream->lc3_decoder = lc3_setup_decoder(frame_duration_us, freq_hz, USB_SAMPLE_RATE,