Codec Extensibility A2DP HAL Reference Implementation
Test: m
Bug: 297037759
Change-Id: I84b32c2ef22da8c3e920e497501b9f16feaf803c
diff --git a/bluetooth/audio/aidl/default/A2dpOffloadCodecSbc.cpp b/bluetooth/audio/aidl/default/A2dpOffloadCodecSbc.cpp
new file mode 100644
index 0000000..36d8f72
--- /dev/null
+++ b/bluetooth/audio/aidl/default/A2dpOffloadCodecSbc.cpp
@@ -0,0 +1,510 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed 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 "A2dpOffloadCodecSbc.h"
+
+#include <algorithm>
+
+#include "A2dpBits.h"
+
+namespace aidl::android::hardware::bluetooth::audio {
+
+/**
+ * SBC Local Capabilities
+ */
+
+enum : bool {
+ kEnableSamplingFrequency44100 = true,
+ kEnableSamplingFrequency48000 = true,
+};
+
+enum : bool {
+ kEnableChannelModeMono = true,
+ kEnableChannelModeDualChannel = true,
+ kEnableChannelModeStereo = true,
+ kEnableChannelModeJointStereo = true,
+};
+
+enum : bool {
+ kEnableBlockLength4 = true,
+ kEnableBlockLength8 = true,
+ kEnableBlockLength12 = true,
+ kEnableBlockLength16 = true,
+};
+
+enum : bool {
+ kEnableSubbands4 = true,
+ kEnableSubbands8 = true,
+};
+
+enum : bool {
+ kEnableAllocationMethodSnr = true,
+ kEnableAllocationMethodLoudness = true,
+};
+
+enum : uint8_t {
+ kDefaultMinimumBitpool = 2,
+ kDefaultMaximumBitpool = 250,
+};
+
+enum : int {
+ kBitdepth = 16,
+};
+
+/**
+ * SBC Signaling format [A2DP - 4.3]
+ */
+
+// clang-format off
+
+constexpr A2dpBits::Range kSamplingFrequency ( 0, 3 );
+constexpr A2dpBits::Range kChannelMode ( 4, 7 );
+constexpr A2dpBits::Range kBlockLength ( 8, 11 );
+constexpr A2dpBits::Range kSubbands ( 12, 13 );
+constexpr A2dpBits::Range kAllocationMethod ( 14, 15 );
+constexpr A2dpBits::Range kMinimumBitpool ( 16, 23 );
+constexpr A2dpBits::Range kMaximumBitpool ( 24, 31 );
+constexpr size_t kCapabilitiesSize = 32/8;
+
+// clang-format on
+
+enum {
+ kSamplingFrequency16000 = kSamplingFrequency.first,
+ kSamplingFrequency32000,
+ kSamplingFrequency44100,
+ kSamplingFrequency48000
+};
+
+enum {
+ kChannelModeMono = kChannelMode.first,
+ kChannelModeDualChannel,
+ kChannelModeStereo,
+ kChannelModeJointStereo
+};
+
+enum {
+ kBlockLength4 = kBlockLength.first,
+ kBlockLength8,
+ kBlockLength12,
+ kBlockLength16
+};
+
+enum { kSubbands8 = kSubbands.first, kSubbands4 };
+
+enum {
+ kAllocationMethodSnr = kAllocationMethod.first,
+ kAllocationMethodLoudness
+};
+
+/**
+ * SBC Conversion functions
+ */
+
+static int GetSamplingFrequencyBit(int32_t sampling_frequency) {
+ switch (sampling_frequency) {
+ case 16000:
+ return kSamplingFrequency16000;
+ case 32000:
+ return kSamplingFrequency32000;
+ case 44100:
+ return kSamplingFrequency44100;
+ case 48000:
+ return kSamplingFrequency48000;
+ default:
+ return -1;
+ }
+}
+
+static int32_t GetSamplingFrequencyValue(int sampling_frequency) {
+ switch (sampling_frequency) {
+ case kSamplingFrequency16000:
+ return 16000;
+ case kSamplingFrequency32000:
+ return 32000;
+ case kSamplingFrequency44100:
+ return 44100;
+ case kSamplingFrequency48000:
+ return 48000;
+ default:
+ return 0;
+ }
+}
+
+static int GetChannelModeBit(ChannelMode channel_mode) {
+ switch (channel_mode) {
+ case ChannelMode::STEREO:
+ return kChannelModeJointStereo | kChannelModeStereo;
+ case ChannelMode::DUALMONO:
+ return kChannelModeDualChannel;
+ case ChannelMode::MONO:
+ return kChannelModeMono;
+ default:
+ return -1;
+ }
+}
+
+static ChannelMode GetChannelModeEnum(int channel_mode) {
+ switch (channel_mode) {
+ case kChannelModeMono:
+ return ChannelMode::MONO;
+ case kChannelModeDualChannel:
+ return ChannelMode::DUALMONO;
+ case kChannelModeStereo:
+ case kChannelModeJointStereo:
+ return ChannelMode::STEREO;
+ default:
+ return ChannelMode::UNKNOWN;
+ }
+}
+
+static int32_t GetBlockLengthValue(int block_length) {
+ switch (block_length) {
+ case kBlockLength4:
+ return 4;
+ case kBlockLength8:
+ return 8;
+ case kBlockLength12:
+ return 12;
+ case kBlockLength16:
+ return 16;
+ default:
+ return 0;
+ }
+}
+
+static int32_t GetSubbandsValue(int subbands) {
+ switch (subbands) {
+ case kSubbands4:
+ return 4;
+ case kSubbands8:
+ return 8;
+ default:
+ return 0;
+ }
+}
+
+static SbcParameters::AllocationMethod GetAllocationMethodEnum(
+ int allocation_method) {
+ switch (allocation_method) {
+ case kAllocationMethodSnr:
+ return SbcParameters::AllocationMethod::SNR;
+ case kAllocationMethodLoudness:
+ default:
+ return SbcParameters::AllocationMethod::LOUDNESS;
+ }
+}
+
+static int32_t GetSamplingFrequencyValue(const A2dpBits& configuration) {
+ return GetSamplingFrequencyValue(
+ configuration.find_active_bit(kSamplingFrequency));
+}
+
+static int32_t GetBlockLengthValue(const A2dpBits& configuration) {
+ return GetBlockLengthValue(configuration.find_active_bit(kBlockLength));
+}
+
+static int32_t GetSubbandsValue(const A2dpBits& configuration) {
+ return GetSubbandsValue(configuration.find_active_bit(kSubbands));
+}
+
+static int GetFrameSize(const A2dpBits& configuration, int bitpool) {
+ const int kSbcHeaderSize = 4;
+ int subbands = GetSubbandsValue(configuration);
+ int blocks = GetBlockLengthValue(configuration);
+
+ unsigned bits =
+ ((4 * subbands) << !configuration.get(kChannelModeMono)) +
+ ((blocks * bitpool) << configuration.get(kChannelModeDualChannel)) +
+ ((configuration.get(kChannelModeJointStereo) ? subbands : 0));
+
+ return kSbcHeaderSize + ((bits + 7) >> 3);
+}
+
+static int GetBitrate(const A2dpBits& configuration, int bitpool) {
+ int sampling_frequency = GetSamplingFrequencyValue(configuration);
+ int subbands = GetSubbandsValue(configuration);
+ int blocks = GetBlockLengthValue(configuration);
+ int bits = 8 * GetFrameSize(configuration, bitpool);
+
+ return (bits * sampling_frequency) / (blocks * subbands);
+}
+
+static uint8_t GetBitpool(const A2dpBits& configuration, int bitrate) {
+ int bitpool = 0;
+
+ for (int i = 128; i; i >>= 1)
+ if (bitrate > GetBitrate(configuration, bitpool + i)) {
+ bitpool += i;
+ }
+
+ return std::clamp(bitpool, 2, 250);
+}
+
+/**
+ * SBC Class implementation
+ */
+
+const A2dpOffloadCodecSbc* A2dpOffloadCodecSbc::GetInstance() {
+ static A2dpOffloadCodecSbc instance;
+ return &instance;
+}
+
+A2dpOffloadCodecSbc::A2dpOffloadCodecSbc()
+ : A2dpOffloadCodec(info_),
+ info_({.id = CodecId(CodecId::A2dp::SBC), .name = "SBC"}) {
+ info_.transport.set<CodecInfo::Transport::Tag::a2dp>();
+ auto& a2dp_info = info_.transport.get<CodecInfo::Transport::Tag::a2dp>();
+
+ /* --- Setup Capabilities --- */
+
+ a2dp_info.capabilities.resize(kCapabilitiesSize);
+ std::fill(begin(a2dp_info.capabilities), end(a2dp_info.capabilities), 0);
+
+ auto capabilities = A2dpBits(a2dp_info.capabilities);
+
+ capabilities.set(kSamplingFrequency44100, kEnableSamplingFrequency44100);
+ capabilities.set(kSamplingFrequency48000, kEnableSamplingFrequency48000);
+
+ capabilities.set(kChannelModeMono, kEnableChannelModeMono);
+ capabilities.set(kChannelModeDualChannel, kEnableChannelModeDualChannel);
+ capabilities.set(kChannelModeStereo, kEnableChannelModeStereo);
+ capabilities.set(kChannelModeJointStereo, kEnableChannelModeJointStereo);
+
+ capabilities.set(kBlockLength4, kEnableBlockLength4);
+ capabilities.set(kBlockLength8, kEnableBlockLength8);
+ capabilities.set(kBlockLength12, kEnableBlockLength12);
+ capabilities.set(kBlockLength16, kEnableBlockLength16);
+
+ capabilities.set(kSubbands4, kEnableSubbands4);
+ capabilities.set(kSubbands8, kEnableSubbands8);
+
+ capabilities.set(kSubbands4, kEnableSubbands4);
+ capabilities.set(kSubbands8, kEnableSubbands8);
+
+ capabilities.set(kAllocationMethodSnr, kEnableAllocationMethodSnr);
+ capabilities.set(kAllocationMethodLoudness, kEnableAllocationMethodLoudness);
+
+ capabilities.set(kMinimumBitpool, kDefaultMinimumBitpool);
+ capabilities.set(kMaximumBitpool, kDefaultMaximumBitpool);
+
+ /* --- Setup Sampling Frequencies --- */
+
+ auto& sampling_frequency = a2dp_info.samplingFrequencyHz;
+
+ for (auto v : {16000, 32000, 44100, 48000})
+ if (capabilities.get(GetSamplingFrequencyBit(int32_t(v))))
+ sampling_frequency.push_back(v);
+
+ /* --- Setup Channel Modes --- */
+
+ auto& channel_modes = a2dp_info.channelMode;
+
+ for (auto v : {ChannelMode::MONO, ChannelMode::DUALMONO, ChannelMode::STEREO})
+ if (capabilities.get(GetChannelModeBit(v))) channel_modes.push_back(v);
+
+ /* --- Setup Bitdepth --- */
+
+ a2dp_info.bitdepth.push_back(kBitdepth);
+}
+
+A2dpStatus A2dpOffloadCodecSbc::ParseConfiguration(
+ const std::vector<uint8_t>& configuration,
+ CodecParameters* codec_parameters, SbcParameters* sbc_parameters) const {
+ auto& a2dp_info = info.transport.get<CodecInfo::Transport::Tag::a2dp>();
+
+ if (configuration.size() != a2dp_info.capabilities.size())
+ return A2dpStatus::BAD_LENGTH;
+
+ auto config = A2dpBits(configuration);
+ auto lcaps = A2dpBits(a2dp_info.capabilities);
+
+ /* --- Check Sampling Frequency --- */
+
+ int sampling_frequency = config.find_active_bit(kSamplingFrequency);
+ if (sampling_frequency < 0) return A2dpStatus::INVALID_SAMPLING_FREQUENCY;
+ if (!lcaps.get(sampling_frequency))
+ return A2dpStatus::NOT_SUPPORTED_SAMPLING_FREQUENCY;
+
+ /* --- Check Channel Mode --- */
+
+ int channel_mode = config.find_active_bit(kChannelMode);
+ if (channel_mode < 0) return A2dpStatus::INVALID_CHANNEL_MODE;
+ if (!lcaps.get(channel_mode)) return A2dpStatus::NOT_SUPPORTED_CHANNEL_MODE;
+
+ /* --- Check Block Length --- */
+
+ int block_length = config.find_active_bit(kBlockLength);
+ if (block_length < 0) return A2dpStatus::INVALID_BLOCK_LENGTH;
+
+ /* --- Check Subbands --- */
+
+ int subbands = config.find_active_bit(kSubbands);
+ if (subbands < 0) return A2dpStatus::INVALID_SUBBANDS;
+ if (!lcaps.get(subbands)) return A2dpStatus::NOT_SUPPORTED_SUBBANDS;
+
+ /* --- Check Allocation Method --- */
+
+ int allocation_method = config.find_active_bit(kAllocationMethod);
+ if (allocation_method < 0) return A2dpStatus::INVALID_ALLOCATION_METHOD;
+ if (!lcaps.get(allocation_method))
+ return A2dpStatus::NOT_SUPPORTED_ALLOCATION_METHOD;
+
+ /* --- Check Bitpool --- */
+
+ uint8_t min_bitpool = config.get(kMinimumBitpool);
+ if (min_bitpool < 2 || min_bitpool > 250)
+ return A2dpStatus::INVALID_MINIMUM_BITPOOL_VALUE;
+ if (min_bitpool < lcaps.get(kMinimumBitpool))
+ return A2dpStatus::NOT_SUPPORTED_MINIMUM_BITPOOL_VALUE;
+
+ uint8_t max_bitpool = config.get(kMaximumBitpool);
+ if (max_bitpool < 2 || max_bitpool > 250)
+ return A2dpStatus::INVALID_MAXIMUM_BITPOOL_VALUE;
+ if (max_bitpool > lcaps.get(kMaximumBitpool))
+ return A2dpStatus::NOT_SUPPORTED_MAXIMUM_BITPOOL_VALUE;
+
+ /* --- Return --- */
+
+ codec_parameters->channelMode = GetChannelModeEnum(channel_mode);
+ codec_parameters->samplingFrequencyHz =
+ GetSamplingFrequencyValue(sampling_frequency);
+ codec_parameters->bitdepth = kBitdepth;
+
+ codec_parameters->minBitrate = GetBitrate(config, min_bitpool);
+ codec_parameters->maxBitrate = GetBitrate(config, max_bitpool);
+
+ if (sbc_parameters) {
+ sbc_parameters->block_length = GetBlockLengthValue(block_length);
+ sbc_parameters->subbands = GetSubbandsValue(subbands);
+ sbc_parameters->allocation_method =
+ GetAllocationMethodEnum(allocation_method);
+ sbc_parameters->min_bitpool = min_bitpool;
+ sbc_parameters->max_bitpool = max_bitpool;
+ }
+
+ return A2dpStatus::OK;
+}
+
+bool A2dpOffloadCodecSbc::BuildConfiguration(
+ const std::vector<uint8_t>& remote_capabilities,
+ const std::optional<CodecParameters>& hint,
+ std::vector<uint8_t>* configuration) const {
+ auto& a2dp_info = info.transport.get<CodecInfo::Transport::Tag::a2dp>();
+
+ if (remote_capabilities.size() != a2dp_info.capabilities.size()) return false;
+
+ auto lcaps = A2dpBits(a2dp_info.capabilities);
+ auto rcaps = A2dpBits(remote_capabilities);
+
+ configuration->resize(a2dp_info.capabilities.size());
+ std::fill(begin(*configuration), end(*configuration), 0);
+ auto config = A2dpBits(*configuration);
+
+ /* --- Select Sampling Frequency --- */
+
+ auto sf_hint = hint ? GetSamplingFrequencyBit(hint->samplingFrequencyHz) : -1;
+
+ if (sf_hint >= 0 && lcaps.get(sf_hint) && rcaps.get(sf_hint))
+ config.set(sf_hint);
+ else if (lcaps.get(kSamplingFrequency44100) &&
+ rcaps.get(kSamplingFrequency44100))
+ config.set(kSamplingFrequency44100);
+ else if (lcaps.get(kSamplingFrequency48000) &&
+ rcaps.get(kSamplingFrequency48000))
+ config.set(kSamplingFrequency48000);
+ else
+ return false;
+
+ /* --- Select Channel Mode --- */
+
+ auto cm_hint = hint ? GetChannelModeBit(hint->channelMode) : -1;
+
+ if (cm_hint >= 0 && lcaps.get(cm_hint) && rcaps.get(cm_hint))
+ config.set(cm_hint);
+ else if (lcaps.get(kChannelModeJointStereo) &&
+ rcaps.get(kChannelModeJointStereo))
+ config.set(kChannelModeJointStereo);
+ else if (lcaps.get(kChannelModeStereo) && rcaps.get(kChannelModeStereo))
+ config.set(kChannelModeStereo);
+ else if (lcaps.get(kChannelModeDualChannel) &&
+ rcaps.get(kChannelModeDualChannel))
+ config.set(kChannelModeDualChannel);
+ else if (lcaps.get(kChannelModeMono) && rcaps.get(kChannelModeMono))
+ config.set(kChannelModeMono);
+ else
+ return false;
+
+ /* --- Select Block Length --- */
+
+ if (lcaps.get(kBlockLength16) && rcaps.get(kBlockLength16))
+ config.set(kBlockLength16);
+ else if (lcaps.get(kBlockLength12) && rcaps.get(kBlockLength12))
+ config.set(kBlockLength12);
+ else if (lcaps.get(kBlockLength8) && rcaps.get(kBlockLength8))
+ config.set(kBlockLength8);
+ else if (lcaps.get(kBlockLength4) && rcaps.get(kBlockLength4))
+ config.set(kBlockLength4);
+ else
+ return false;
+
+ /* --- Select Subbands --- */
+
+ if (lcaps.get(kSubbands8) && rcaps.get(kSubbands8))
+ config.set(kSubbands8);
+ else if (lcaps.get(kSubbands4) && rcaps.get(kSubbands4))
+ config.set(kSubbands4);
+ else
+ return false;
+
+ /* --- Select Allocation method --- */
+
+ if (lcaps.get(kAllocationMethodLoudness) &&
+ rcaps.get(kAllocationMethodLoudness))
+ config.set(kAllocationMethodLoudness);
+ else if (lcaps.get(kAllocationMethodSnr) && rcaps.get(kAllocationMethodSnr))
+ config.set(kAllocationMethodSnr);
+ else
+ return false;
+
+ /* --- Select Bitpool --- */
+
+ uint8_t min_bitpool = rcaps.get(kMinimumBitpool);
+ uint8_t max_bitpool = rcaps.get(kMaximumBitpool);
+
+ if (min_bitpool < 2 || min_bitpool > 250 || max_bitpool < 2 ||
+ max_bitpool > 250 || min_bitpool > max_bitpool) {
+ min_bitpool = 2;
+ max_bitpool = 250;
+ }
+
+ min_bitpool = std::max(min_bitpool, uint8_t(lcaps.get(kMinimumBitpool)));
+ max_bitpool = std::max(max_bitpool, uint8_t(lcaps.get(kMaximumBitpool)));
+
+ if (hint) {
+ min_bitpool =
+ std::max(min_bitpool, GetBitpool(*configuration, hint->minBitrate));
+ if (hint->maxBitrate && hint->maxBitrate >= hint->minBitrate)
+ max_bitpool =
+ std::min(max_bitpool, GetBitpool(*configuration, hint->maxBitrate));
+ }
+
+ config.set(kMinimumBitpool, min_bitpool);
+ config.set(kMaximumBitpool, max_bitpool);
+
+ return true;
+}
+
+} // namespace aidl::android::hardware::bluetooth::audio