bluetooth: Add aptX support via GStreamer

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/440>

meson.build

@@ -748,6 +748,7 @@ have_bluez5_gstreamer = false
 if bluez5_gst_dep.found() and bluez5_gstapp_dep.found()
   have_bluez5_gstreamer = true
   cdata.set('HAVE_GSTLDAC', 1)
+  cdata.set('HAVE_GSTAPTX', 1)
 endif
 
 # These are required for the CMake file generation

src/modules/bluetooth/a2dp-codec-aptx-gst.c

@@ -0,0 +1,395 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2020 Sanchayan Maity <sanchayan@asymptotic.io>
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <pulsecore/log.h>
+#include <pulsecore/macro.h>
+#include <pulsecore/once.h>
+#include <pulse/sample.h>
+
+#include <arpa/inet.h>
+
+#include "a2dp-codecs.h"
+#include "a2dp-codec-api.h"
+#include "a2dp-codec-gst.h"
+#include "rtp.h"
+
+static bool can_accept_capabilities_common(const a2dp_aptx_t *capabilities, uint32_t vendor_id, uint16_t codec_id) {
+    if (A2DP_GET_VENDOR_ID(capabilities->info) != vendor_id || A2DP_GET_CODEC_ID(capabilities->info) != codec_id)
+        return false;
+
+    if (!(capabilities->frequency & (APTX_SAMPLING_FREQ_16000 | APTX_SAMPLING_FREQ_32000 |
+                                     APTX_SAMPLING_FREQ_44100 | APTX_SAMPLING_FREQ_48000)))
+        return false;
+
+    if (!(capabilities->channel_mode & APTX_CHANNEL_MODE_STEREO))
+        return false;
+
+    return true;
+}
+
+static bool can_accept_capabilities(const uint8_t *capabilities_buffer, uint8_t capabilities_size, bool for_encoding) {
+    const a2dp_aptx_t *capabilities = (const a2dp_aptx_t *) capabilities_buffer;
+
+    if (capabilities_size != sizeof(*capabilities))
+        return false;
+
+    return can_accept_capabilities_common(capabilities, APTX_VENDOR_ID, APTX_CODEC_ID);
+}
+
+static bool can_accept_capabilities_hd(const uint8_t *capabilities_buffer, uint8_t capabilities_size, bool for_encoding) {
+    const a2dp_aptx_hd_t *capabilities = (const a2dp_aptx_hd_t *) capabilities_buffer;
+
+    if (capabilities_size != sizeof(*capabilities))
+        return false;
+
+    return can_accept_capabilities_common(&capabilities->aptx, APTX_HD_VENDOR_ID, APTX_HD_CODEC_ID);
+}
+
+static const char *choose_remote_endpoint(const pa_hashmap *capabilities_hashmap, const pa_sample_spec *default_sample_spec, bool for_encoding) {
+    const pa_a2dp_codec_capabilities *a2dp_capabilities;
+    const char *key;
+    void *state;
+
+    /* There is no preference, just choose random valid entry */
+    PA_HASHMAP_FOREACH_KV(key, a2dp_capabilities, capabilities_hashmap, state) {
+        if (can_accept_capabilities(a2dp_capabilities->buffer, a2dp_capabilities->size, for_encoding))
+            return key;
+    }
+
+    return NULL;
+}
+
+static const char *choose_remote_endpoint_hd(const pa_hashmap *capabilities_hashmap, const pa_sample_spec *default_sample_spec, bool for_encoding) {
+    const pa_a2dp_codec_capabilities *a2dp_capabilities;
+    const char *key;
+    void *state;
+
+    /* There is no preference, just choose random valid entry */
+    PA_HASHMAP_FOREACH_KV(key, a2dp_capabilities, capabilities_hashmap, state) {
+        if (can_accept_capabilities_hd(a2dp_capabilities->buffer, a2dp_capabilities->size, for_encoding))
+            return key;
+    }
+
+    return NULL;
+}
+
+static void fill_capabilities_common(a2dp_aptx_t *capabilities, uint32_t vendor_id, uint16_t codec_id) {
+    capabilities->info = A2DP_SET_VENDOR_ID_CODEC_ID(vendor_id, codec_id);
+    capabilities->channel_mode = APTX_CHANNEL_MODE_STEREO;
+    capabilities->frequency = APTX_SAMPLING_FREQ_16000 | APTX_SAMPLING_FREQ_32000 |
+                              APTX_SAMPLING_FREQ_44100 | APTX_SAMPLING_FREQ_48000;
+}
+
+static uint8_t fill_capabilities(uint8_t capabilities_buffer[MAX_A2DP_CAPS_SIZE]) {
+    a2dp_aptx_t *capabilities = (a2dp_aptx_t *) capabilities_buffer;
+
+    pa_zero(*capabilities);
+    fill_capabilities_common(capabilities, APTX_VENDOR_ID, APTX_CODEC_ID);
+    return sizeof(*capabilities);
+}
+
+static uint8_t fill_capabilities_hd(uint8_t capabilities_buffer[MAX_A2DP_CAPS_SIZE]) {
+    a2dp_aptx_hd_t *capabilities = (a2dp_aptx_hd_t *) capabilities_buffer;
+
+    pa_zero(*capabilities);
+    fill_capabilities_common(&capabilities->aptx, APTX_HD_VENDOR_ID, APTX_HD_CODEC_ID);
+    return sizeof(*capabilities);
+}
+
+static bool is_configuration_valid_common(const a2dp_aptx_t *config, uint32_t vendor_id, uint16_t codec_id) {
+    if (A2DP_GET_VENDOR_ID(config->info) != vendor_id || A2DP_GET_CODEC_ID(config->info) != codec_id) {
+        pa_log_error("Invalid vendor codec information in configuration");
+        return false;
+    }
+
+    if (config->frequency != APTX_SAMPLING_FREQ_16000 && config->frequency != APTX_SAMPLING_FREQ_32000 &&
+        config->frequency != APTX_SAMPLING_FREQ_44100 && config->frequency != APTX_SAMPLING_FREQ_48000) {
+        pa_log_error("Invalid sampling frequency in configuration");
+        return false;
+    }
+
+    if (config->channel_mode != APTX_CHANNEL_MODE_STEREO) {
+        pa_log_error("Invalid channel mode in configuration");
+        return false;
+    }
+
+    return true;
+}
+
+static bool is_configuration_valid(const uint8_t *config_buffer, uint8_t config_size) {
+    const a2dp_aptx_t *config = (const a2dp_aptx_t *) config_buffer;
+
+    if (config_size != sizeof(*config)) {
+        pa_log_error("Invalid size of config buffer");
+        return false;
+    }
+
+    return is_configuration_valid_common(config, APTX_VENDOR_ID, APTX_CODEC_ID);
+}
+
+static bool is_configuration_valid_hd(const uint8_t *config_buffer, uint8_t config_size) {
+    const a2dp_aptx_hd_t *config = (const a2dp_aptx_hd_t *) config_buffer;
+
+    if (config_size != sizeof(*config)) {
+        pa_log_error("Invalid size of config buffer");
+        return false;
+    }
+
+    return is_configuration_valid_common(&config->aptx, APTX_HD_VENDOR_ID, APTX_HD_CODEC_ID);
+}
+
+static int fill_preferred_configuration_common(const pa_sample_spec *default_sample_spec, const a2dp_aptx_t *capabilities, a2dp_aptx_t *config, uint32_t vendor_id, uint16_t codec_id) {
+    int i;
+
+    static const struct {
+        uint32_t rate;
+        uint8_t cap;
+    } freq_table[] = {
+        { 16000U, APTX_SAMPLING_FREQ_16000 },
+        { 32000U, APTX_SAMPLING_FREQ_32000 },
+        { 44100U, APTX_SAMPLING_FREQ_44100 },
+        { 48000U, APTX_SAMPLING_FREQ_48000 }
+    };
+
+    if (A2DP_GET_VENDOR_ID(capabilities->info) != vendor_id || A2DP_GET_CODEC_ID(capabilities->info) != codec_id) {
+        pa_log_error("No supported vendor codec information");
+        return -1;
+    }
+
+    config->info = A2DP_SET_VENDOR_ID_CODEC_ID(vendor_id, codec_id);
+
+    if (!(capabilities->channel_mode & APTX_CHANNEL_MODE_STEREO)) {
+        pa_log_error("No supported channel modes");
+        return -1;
+    }
+
+    config->channel_mode = APTX_CHANNEL_MODE_STEREO;
+
+    /* Find the lowest freq that is at least as high as the requested sampling rate */
+    for (i = 0; (unsigned) i < PA_ELEMENTSOF(freq_table); i++) {
+        if (freq_table[i].rate >= default_sample_spec->rate && (capabilities->frequency & freq_table[i].cap)) {
+            config->frequency = freq_table[i].cap;
+            break;
+        }
+    }
+
+    if ((unsigned) i == PA_ELEMENTSOF(freq_table)) {
+        for (--i; i >= 0; i--) {
+            if (capabilities->frequency & freq_table[i].cap) {
+                config->frequency = freq_table[i].cap;
+                break;
+            }
+        }
+
+        if (i < 0) {
+            pa_log_error("Not suitable sample rate");
+            return false;
+        }
+    }
+
+    return 0;
+}
+
+static uint8_t fill_preferred_configuration(const pa_sample_spec *default_sample_spec, const uint8_t *capabilities_buffer, uint8_t capabilities_size, uint8_t config_buffer[MAX_A2DP_CAPS_SIZE]) {
+    a2dp_aptx_t *config = (a2dp_aptx_t *) config_buffer;
+    const a2dp_aptx_t *capabilities = (const a2dp_aptx_t *) capabilities_buffer;
+
+    if (capabilities_size != sizeof(*capabilities)) {
+        pa_log_error("Invalid size of capabilities buffer");
+        return 0;
+    }
+
+    pa_zero(*config);
+
+    if (fill_preferred_configuration_common(default_sample_spec, capabilities, config, APTX_VENDOR_ID, APTX_CODEC_ID) < 0)
+        return 0;
+
+    return sizeof(*config);
+}
+
+static uint8_t fill_preferred_configuration_hd(const pa_sample_spec *default_sample_spec, const uint8_t *capabilities_buffer, uint8_t capabilities_size, uint8_t config_buffer[MAX_A2DP_CAPS_SIZE]) {
+    a2dp_aptx_hd_t *config = (a2dp_aptx_hd_t *) config_buffer;
+    const a2dp_aptx_hd_t *capabilities = (const a2dp_aptx_hd_t *) capabilities_buffer;
+
+    if (capabilities_size != sizeof(*capabilities)) {
+        pa_log_error("Invalid size of capabilities buffer");
+        return 0;
+    }
+
+    pa_zero(*config);
+
+    if (fill_preferred_configuration_common(default_sample_spec, &capabilities->aptx, &config->aptx, APTX_HD_VENDOR_ID, APTX_HD_CODEC_ID) < 0)
+        return 0;
+
+    return sizeof(*config);
+}
+
+static void *init(bool for_encoding, bool for_backchannel, const uint8_t *config_buffer, uint8_t config_size, pa_sample_spec *sample_spec) {
+    return gst_codec_init(APTX, config_buffer, config_size, sample_spec);
+}
+
+static void *init_hd(bool for_encoding, bool for_backchannel, const uint8_t *config_buffer, uint8_t config_size, pa_sample_spec *sample_spec) {
+    return gst_codec_init(APTX_HD, config_buffer, config_size, sample_spec);
+}
+
+static void deinit(void *codec_info) {
+    return gst_codec_deinit(codec_info);
+}
+
+static int reset(void *codec_info) {
+    return 0;
+}
+
+static int reset_hd(void *codec_info) {
+    struct gst_info *info = (struct gst_info *) codec_info;
+
+    info->seq_num = 0;
+
+    return 0;
+}
+
+static size_t get_block_size(void *codec_info, size_t link_mtu) {
+    /* aptX compression ratio is 6:1 and we need to process one aptX frame (4 bytes) at once */
+    size_t frame_count = (link_mtu / 4);
+
+    return frame_count * 4 * 6;
+}
+
+static size_t get_block_size_hd(void *codec_info, size_t link_mtu) {
+    /* aptX HD compression ratio is 4:1 and we need to process one aptX HD frame (6 bytes) at once, plus aptX HD frames are encapsulated in RTP */
+    size_t rtp_size = sizeof(struct rtp_header);
+    size_t frame_count = (link_mtu - rtp_size) / 6;
+
+    return frame_count * 6 * 4;
+}
+
+static size_t reduce_encoder_bitrate(void *codec_info, size_t write_link_mtu) {
+    return 0;
+}
+
+static size_t encode_buffer(void *codec_info, uint32_t timestamp, const uint8_t *input_buffer, size_t input_size, uint8_t *output_buffer, size_t output_size, size_t *processed) {
+    size_t written;
+
+    written = gst_encode_buffer(codec_info, timestamp, input_buffer, input_size, output_buffer, output_size, processed);
+    if (PA_UNLIKELY(*processed == 0 || *processed != input_size))
+        pa_log_error("aptX encoding error");
+
+    return written;
+}
+
+static size_t encode_buffer_hd(void *codec_info, uint32_t timestamp, const uint8_t *input_buffer, size_t input_size, uint8_t *output_buffer, size_t output_size, size_t *processed) {
+    struct gst_info *info = (struct gst_info *) codec_info;
+    struct rtp_header *header;
+    size_t written;
+
+    if (PA_UNLIKELY(output_size < sizeof(*header))) {
+        *processed = 0;
+        return 0;
+    }
+
+    written = gst_encode_buffer(codec_info, timestamp, input_buffer, input_size, output_buffer + sizeof(*header), output_size - sizeof(*header), processed);
+
+    if (PA_LIKELY(written > 0)) {
+        header = (struct rtp_header *) output_buffer;
+        pa_zero(*header);
+        header->v = 2;
+        header->pt = 96;
+        header->sequence_number = htons(info->seq_num++);
+        header->timestamp = htonl(timestamp);
+        header->ssrc = htonl(1);
+        written += sizeof(*header);
+    }
+
+    return written;
+}
+
+static size_t decode_buffer(void *codec_info, const uint8_t *input_buffer, size_t input_size, uint8_t *output_buffer, size_t output_size, size_t *processed) {
+    size_t written;
+
+    written = gst_decode_buffer(codec_info, input_buffer, input_size, output_buffer, output_size, processed);
+
+    /* Due to aptX latency, aptx_decode starts filling output buffer after 90 input samples.
+     * If input buffer contains less than 90 samples, aptx_decode returns zero (=no output)
+     * but set *processed to non zero as input samples were processed. So do not check for
+     * return value of aptx_decode, zero is valid. Decoding error is indicating by fact that
+     * not all input samples were processed. */
+    if (PA_UNLIKELY(*processed != input_size))
+        pa_log_error("aptX decoding error");
+
+    return written;
+}
+
+static size_t decode_buffer_hd(void *codec_info, const uint8_t *input_buffer, size_t input_size, uint8_t *output_buffer, size_t output_size, size_t *processed) {
+    struct rtp_header *header;
+    size_t written;
+
+    if (PA_UNLIKELY(input_size < sizeof(*header))) {
+        *processed = 0;
+        return 0;
+    }
+
+    header = (struct rtp_header *) input_buffer;
+    written = decode_buffer(codec_info, input_buffer + sizeof(*header), input_size - sizeof(*header), output_buffer, output_size, processed);
+    *processed += sizeof(*header);
+    return written;
+}
+
+const pa_a2dp_codec pa_a2dp_codec_aptx = {
+    .name = "aptx",
+    .description = "aptX",
+    .id = { A2DP_CODEC_VENDOR, APTX_VENDOR_ID, APTX_CODEC_ID },
+    .support_backchannel = false,
+    .can_accept_capabilities = can_accept_capabilities,
+    .choose_remote_endpoint = choose_remote_endpoint,
+    .fill_capabilities = fill_capabilities,
+    .is_configuration_valid = is_configuration_valid,
+    .fill_preferred_configuration = fill_preferred_configuration,
+    .init = init,
+    .deinit = deinit,
+    .reset = reset,
+    .get_read_block_size = get_block_size,
+    .get_write_block_size = get_block_size,
+    .reduce_encoder_bitrate = reduce_encoder_bitrate,
+    .encode_buffer = encode_buffer,
+    .decode_buffer = decode_buffer,
+};
+
+const pa_a2dp_codec pa_a2dp_codec_aptx_hd = {
+    .name = "aptx_hd",
+    .description = "aptX HD",
+    .id = { A2DP_CODEC_VENDOR, APTX_HD_VENDOR_ID, APTX_HD_CODEC_ID },
+    .support_backchannel = false,
+    .can_accept_capabilities = can_accept_capabilities_hd,
+    .choose_remote_endpoint = choose_remote_endpoint_hd,
+    .fill_capabilities = fill_capabilities_hd,
+    .is_configuration_valid = is_configuration_valid_hd,
+    .fill_preferred_configuration = fill_preferred_configuration_hd,
+    .init = init_hd,
+    .deinit = deinit,
+    .reset = reset_hd,
+    .get_read_block_size = get_block_size_hd,
+    .get_write_block_size = get_block_size_hd,
+    .reduce_encoder_bitrate = reduce_encoder_bitrate,
+    .encode_buffer = encode_buffer_hd,
+    .decode_buffer = decode_buffer_hd,
+};

src/modules/bluetooth/a2dp-codec-util.c

@@ -27,6 +27,10 @@
 #include "a2dp-codec-util.h"
 
 extern const pa_a2dp_codec pa_a2dp_codec_sbc;
+#ifdef HAVE_GSTAPTX
+extern const pa_a2dp_codec pa_a2dp_codec_aptx;
+extern const pa_a2dp_codec pa_a2dp_codec_aptx_hd;
+#endif
 #ifdef HAVE_GSTLDAC
 extern const pa_a2dp_codec pa_a2dp_codec_ldac_eqmid_hq;
 extern const pa_a2dp_codec pa_a2dp_codec_ldac_eqmid_sq;
@@ -40,6 +44,10 @@ static const pa_a2dp_codec *pa_a2dp_codecs[] = {
     &pa_a2dp_codec_ldac_eqmid_hq,
     &pa_a2dp_codec_ldac_eqmid_sq,
     &pa_a2dp_codec_ldac_eqmid_mq,
+#endif
+#ifdef HAVE_GSTAPTX
+    &pa_a2dp_codec_aptx_hd,
+    &pa_a2dp_codec_aptx,
 #endif
     &pa_a2dp_codec_sbc,
 };

src/modules/bluetooth/meson.build

@@ -24,6 +24,7 @@ if have_bluez5_gstreamer
   libbluez5_util_headers += [ 'a2dp-codec-gst.h' ]
   libbluez5_util_sources += [ 'a2dp-codec-gst.c' ]
   libbluez5_util_sources += [ 'a2dp-codec-ldac-gst.c' ]
+  libbluez5_util_sources += [ 'a2dp-codec-aptx-gst.c' ]
 endif
 
 libbluez5_util = shared_library('bluez5-util',