apps: add Auracast USB sample with LC3 codec

This adds sample that acts as USB sound device. Audio signal is coded
using LC3 and broadacasted using Auracast package.

apps/auracast_usb/include/usb_audio.h

@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef H_USB_AUDIO_
+#define H_USB_AUDIO_
+
+#include <stdint.h>
+
+typedef void (* usb_audio_sample_rate_cb_t)(uint32_t);
+
+/* Set default sample rate, should only be used before USB is initialized */
+void usb_desc_sample_rate_set(uint32_t sample_rate);
+
+/* Set callback to receive sample rate set by USB host */
+void usb_audio_sample_rate_cb_set(usb_audio_sample_rate_cb_t cb);
+
+/* Get current sample rate */
+uint32_t usb_audio_sample_rate_get(void);
+
+#endif /* H_USB_AUDIO_ */

apps/auracast_usb/pkg.yml

@@ -0,0 +1,45 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+pkg.name: apps/auracast_usb
+pkg.type: app
+pkg.description: Auracast sample application.
+
+pkg.author: "Krzysztof Kopyściński"
+pkg.email: "krzysztof.kopyscinski@codecoup.pl"
+pkg.homepage: "http://mynewt.apache.org/"
+pkg.keywords:
+
+pkg.deps:
+    - "@apache-mynewt-core/sys/config"
+    - nimble/host
+    - nimble/host/util
+    - nimble/host/services/gap
+    - nimble/host/store/config
+    - "@apache-mynewt-core/kernel/os"
+    - "@apache-mynewt-core/sys/console"
+    - "@apache-mynewt-core/sys/log"
+    - "@apache-mynewt-core/sys/stats"
+    - "@apache-mynewt-core/sys/sysinit"
+    - "@apache-mynewt-core/sys/id"
+    - "@apache-mynewt-core/hw/usb/tinyusb"
+    - "@apache-mynewt-nimble/nimble/host/services/auracast"
+    - "@apache-mynewt-nimble/ext/liblc3"
+
+pkg.init:
+    audio_usb_init: 402

apps/auracast_usb/src/app_priv.h

@@ -0,0 +1,44 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef H_APP_PRIV_
+#define H_APP_PRIV_
+
+#include <syscfg/syscfg.h>
+
+#ifndef MIN
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+#define AUDIO_CHANNELS          MYNEWT_VAL(AURACAST_CHAN_NUM)
+#define AUDIO_SAMPLE_SIZE       sizeof(int16_t)
+
+#define LC3_FRAME_DURATION      (MYNEWT_VAL(LC3_FRAME_DURATION))
+#define LC3_SAMPLING_FREQ       (MYNEWT_VAL(LC3_SAMPLING_FREQ))
+#define LC3_BITRATE             (MYNEWT_VAL(LC3_BITRATE))
+#define LC3_FPDT                (LC3_SAMPLING_FREQ * LC3_FRAME_DURATION / 1000000)
+#define BIG_NUM_BIS             (MIN(AUDIO_CHANNELS, MYNEWT_VAL(BIG_NUM_BIS)))
+
+struct chan {
+    void *encoder;
+    uint16_t handle;
+};
+
+extern struct chan chans[AUDIO_CHANNELS];
+#endif /* H_APP_PRIV_ */

apps/auracast_usb/src/audio_usb.c

@@ -0,0 +1,187 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include <assert.h>
+#include <string.h>
+#include <syscfg/syscfg.h>
+#include <os/os.h>
+#include <common/tusb_fifo.h>
+#include <class/audio/audio_device.h>
+#include <usb_audio.h>
+
+#include <lc3.h>
+#include <nrf_clock.h>
+
+#include "host/ble_gap.h"
+
+#include "app_priv.h"
+
+static uint8_t g_usb_enabled;
+
+static void usb_data_func(struct os_event *ev);
+
+struct chan chans[AUDIO_CHANNELS];
+
+static struct os_event usb_data_ev = {
+    .ev_cb = usb_data_func,
+};
+
+static uint32_t frame_bytes_lc3;
+static uint16_t big_sdu;
+
+static int16_t samples[96000 / 100 * 2 * 2];
+static uint8_t samples_out[96000 / 100 * 2];
+static int samples_idx = 0;
+
+static uint32_t pkt_counter = 0;
+
+static void
+usb_data_func(struct os_event *ev)
+{
+    int ch_idx;
+    unsigned int num_bytes;
+    unsigned int num_samples;
+    unsigned int num_frames;
+    unsigned int frames_count;
+    int read;
+    int skip;
+
+    if (!g_usb_enabled) {
+        tud_audio_clear_ep_out_ff();
+        return;
+    }
+
+    while ((num_bytes = tud_audio_available()) > 0) {
+        num_samples = num_bytes / AUDIO_SAMPLE_SIZE;
+        num_frames = num_samples / MYNEWT_VAL(AURACAST_CHAN_NUM);
+        num_bytes = num_frames * AUDIO_SAMPLE_SIZE * MYNEWT_VAL(AURACAST_CHAN_NUM);
+
+        assert(samples_idx + num_samples < ARRAY_SIZE(samples));
+
+        read = tud_audio_read(&samples[samples_idx], num_bytes);
+
+        assert(read == num_bytes);
+        assert(samples[ARRAY_SIZE(samples) - 1] = 0xaaaa);
+
+        samples_idx += num_samples;
+        assert((samples_idx & 0x80000000) == 0);
+        frames_count = samples_idx / MYNEWT_VAL(AURACAST_CHAN_NUM);
+
+        if (frames_count >= LC3_FPDT) {
+            pkt_counter++;
+            skip = 0;
+
+            for (ch_idx = 0; ch_idx < MYNEWT_VAL(AURACAST_CHAN_NUM); ch_idx++) {
+                if (chans[ch_idx].handle == 0) {
+                    skip = 1;
+                    continue;
+                }
+            }
+
+            if (!skip) {
+                memset(samples_out, 0, sizeof(samples_out));
+                lc3_encode(chans[0].encoder, LC3_PCM_FORMAT_S16,
+                           samples + 0, AUDIO_CHANNELS,
+                           (int)frame_bytes_lc3, samples_out);
+
+                if (AUDIO_CHANNELS == 2) {
+                    ble_iso_tx(chans[0].handle, samples_out, big_sdu);
+
+                    memset(samples_out, 0, sizeof(samples_out));
+                    lc3_encode(chans[1].encoder, LC3_PCM_FORMAT_S16,
+                               samples + 1, AUDIO_CHANNELS,
+                               (int)frame_bytes_lc3, samples_out);
+                    ble_iso_tx(chans[1].handle, samples_out, big_sdu);
+                } else {
+                    ble_iso_tx(chans[0].handle, samples_out, big_sdu);
+                    if (BIG_NUM_BIS == 1) {
+                        memset(samples_out, 0, sizeof(samples_out));
+                        lc3_encode(chans[1].encoder, LC3_PCM_FORMAT_S16,
+                                   samples + 1, AUDIO_CHANNELS,
+                                   (int)frame_bytes_lc3, samples_out);
+                    }
+                    ble_iso_tx(chans[0].handle, samples_out, big_sdu);
+                }
+
+            }
+
+            if (frames_count > LC3_FPDT) {
+                int old_samples_idx = samples_idx;
+                samples_idx -= LC3_FPDT * AUDIO_CHANNELS;
+                memmove(samples, &samples[old_samples_idx],
+                        (old_samples_idx - samples_idx) * AUDIO_SAMPLE_SIZE);
+            } else {
+                samples_idx = 0;
+            }
+        }
+    }
+
+}
+
+bool
+tud_audio_rx_done_post_read_cb(uint8_t rhport, uint16_t n_bytes_received,
+                               uint8_t func_id, uint8_t ep_out,
+                               uint8_t cur_alt_setting)
+{
+    (void)rhport;
+    (void)n_bytes_received;
+    (void)func_id;
+    (void)ep_out;
+    (void)cur_alt_setting;
+
+    if (!usb_data_ev.ev_queued) {
+        os_eventq_put(os_eventq_dflt_get(), &usb_data_ev);
+    }
+
+    return true;
+}
+
+void
+audio_usb_init(void)
+{
+    /* Need to reference those explicitly, so they are always pulled by linker
+     * instead of weak symbols in tinyusb.
+     */
+    (void)tud_audio_rx_done_post_read_cb;
+
+    usb_desc_sample_rate_set(LC3_SAMPLING_FREQ);
+
+    assert(LC3_FPDT == lc3_frame_samples(LC3_FRAME_DURATION,
+                                         LC3_SAMPLING_FREQ));
+
+    memset(samples, 0xaa, sizeof(samples));
+
+    unsigned esize = lc3_encoder_size(LC3_FRAME_DURATION,
+                                      LC3_SAMPLING_FREQ);
+    for (int i = 0; i < AUDIO_CHANNELS; i++) {
+        chans[i].encoder = calloc(1, esize);
+        lc3_setup_encoder(LC3_FRAME_DURATION, LC3_SAMPLING_FREQ,
+                          0, chans[i].encoder);
+    }
+
+#ifdef NRF53_SERIES
+    nrf_clock_hfclk_div_set(NRF_CLOCK, NRF_CLOCK_HFCLK_DIV_1);
+#endif
+
+    g_usb_enabled = 1;
+
+    frame_bytes_lc3 = lc3_frame_bytes(LC3_FRAME_DURATION, LC3_BITRATE);
+    big_sdu = frame_bytes_lc3 *
+              (1 + ((AUDIO_CHANNELS == 2) && (BIG_NUM_BIS == 1)));
+}