| # Copyright 2021-2022 Google LLC |
| # |
| # 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 |
| # |
| # https://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. |
| |
| # ----------------------------------------------------------------------------- |
| # Imports |
| # ----------------------------------------------------------------------------- |
| import struct |
| import logging |
| from collections import namedtuple |
| import bitstruct |
| |
| from .company_ids import COMPANY_IDENTIFIERS |
| from .sdp import ( |
| DataElement, |
| ServiceAttribute, |
| SDP_PUBLIC_BROWSE_ROOT, |
| SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID, |
| SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID, |
| SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID, |
| SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID, |
| SDP_BLUETOOTH_PROFILE_DESCRIPTOR_LIST_ATTRIBUTE_ID, |
| ) |
| from .core import ( |
| BT_L2CAP_PROTOCOL_ID, |
| BT_AUDIO_SOURCE_SERVICE, |
| BT_AUDIO_SINK_SERVICE, |
| BT_AVDTP_PROTOCOL_ID, |
| BT_ADVANCED_AUDIO_DISTRIBUTION_SERVICE, |
| name_or_number, |
| ) |
| |
| |
| # ----------------------------------------------------------------------------- |
| # Logging |
| # ----------------------------------------------------------------------------- |
| logger = logging.getLogger(__name__) |
| |
| |
| # ----------------------------------------------------------------------------- |
| # Constants |
| # ----------------------------------------------------------------------------- |
| # fmt: off |
| |
| A2DP_SBC_CODEC_TYPE = 0x00 |
| A2DP_MPEG_1_2_AUDIO_CODEC_TYPE = 0x01 |
| A2DP_MPEG_2_4_AAC_CODEC_TYPE = 0x02 |
| A2DP_ATRAC_FAMILY_CODEC_TYPE = 0x03 |
| A2DP_NON_A2DP_CODEC_TYPE = 0xFF |
| |
| A2DP_CODEC_TYPE_NAMES = { |
| A2DP_SBC_CODEC_TYPE: 'A2DP_SBC_CODEC_TYPE', |
| A2DP_MPEG_1_2_AUDIO_CODEC_TYPE: 'A2DP_MPEG_1_2_AUDIO_CODEC_TYPE', |
| A2DP_MPEG_2_4_AAC_CODEC_TYPE: 'A2DP_MPEG_2_4_AAC_CODEC_TYPE', |
| A2DP_ATRAC_FAMILY_CODEC_TYPE: 'A2DP_ATRAC_FAMILY_CODEC_TYPE', |
| A2DP_NON_A2DP_CODEC_TYPE: 'A2DP_NON_A2DP_CODEC_TYPE' |
| } |
| |
| |
| SBC_SYNC_WORD = 0x9C |
| |
| SBC_SAMPLING_FREQUENCIES = [ |
| 16000, |
| 22050, |
| 44100, |
| 48000 |
| ] |
| |
| SBC_MONO_CHANNEL_MODE = 0x00 |
| SBC_DUAL_CHANNEL_MODE = 0x01 |
| SBC_STEREO_CHANNEL_MODE = 0x02 |
| SBC_JOINT_STEREO_CHANNEL_MODE = 0x03 |
| |
| SBC_CHANNEL_MODE_NAMES = { |
| SBC_MONO_CHANNEL_MODE: 'SBC_MONO_CHANNEL_MODE', |
| SBC_DUAL_CHANNEL_MODE: 'SBC_DUAL_CHANNEL_MODE', |
| SBC_STEREO_CHANNEL_MODE: 'SBC_STEREO_CHANNEL_MODE', |
| SBC_JOINT_STEREO_CHANNEL_MODE: 'SBC_JOINT_STEREO_CHANNEL_MODE' |
| } |
| |
| SBC_BLOCK_LENGTHS = [4, 8, 12, 16] |
| |
| SBC_SUBBANDS = [4, 8] |
| |
| SBC_SNR_ALLOCATION_METHOD = 0x00 |
| SBC_LOUDNESS_ALLOCATION_METHOD = 0x01 |
| |
| SBC_ALLOCATION_METHOD_NAMES = { |
| SBC_SNR_ALLOCATION_METHOD: 'SBC_SNR_ALLOCATION_METHOD', |
| SBC_LOUDNESS_ALLOCATION_METHOD: 'SBC_LOUDNESS_ALLOCATION_METHOD' |
| } |
| |
| MPEG_2_4_AAC_SAMPLING_FREQUENCIES = [ |
| 8000, |
| 11025, |
| 12000, |
| 16000, |
| 22050, |
| 24000, |
| 32000, |
| 44100, |
| 48000, |
| 64000, |
| 88200, |
| 96000 |
| ] |
| |
| MPEG_2_AAC_LC_OBJECT_TYPE = 0x00 |
| MPEG_4_AAC_LC_OBJECT_TYPE = 0x01 |
| MPEG_4_AAC_LTP_OBJECT_TYPE = 0x02 |
| MPEG_4_AAC_SCALABLE_OBJECT_TYPE = 0x03 |
| |
| MPEG_2_4_OBJECT_TYPE_NAMES = { |
| MPEG_2_AAC_LC_OBJECT_TYPE: 'MPEG_2_AAC_LC_OBJECT_TYPE', |
| MPEG_4_AAC_LC_OBJECT_TYPE: 'MPEG_4_AAC_LC_OBJECT_TYPE', |
| MPEG_4_AAC_LTP_OBJECT_TYPE: 'MPEG_4_AAC_LTP_OBJECT_TYPE', |
| MPEG_4_AAC_SCALABLE_OBJECT_TYPE: 'MPEG_4_AAC_SCALABLE_OBJECT_TYPE' |
| } |
| |
| # fmt: on |
| |
| |
| # ----------------------------------------------------------------------------- |
| def flags_to_list(flags, values): |
| result = [] |
| for i, value in enumerate(values): |
| if flags & (1 << (len(values) - i - 1)): |
| result.append(value) |
| return result |
| |
| |
| # ----------------------------------------------------------------------------- |
| def make_audio_source_service_sdp_records(service_record_handle, version=(1, 3)): |
| # pylint: disable=import-outside-toplevel |
| from .avdtp import AVDTP_PSM |
| |
| version_int = version[0] << 8 | version[1] |
| return [ |
| ServiceAttribute( |
| SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID, |
| DataElement.unsigned_integer_32(service_record_handle), |
| ), |
| ServiceAttribute( |
| SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID, |
| DataElement.sequence([DataElement.uuid(SDP_PUBLIC_BROWSE_ROOT)]), |
| ), |
| ServiceAttribute( |
| SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID, |
| DataElement.sequence([DataElement.uuid(BT_AUDIO_SOURCE_SERVICE)]), |
| ), |
| ServiceAttribute( |
| SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID, |
| DataElement.sequence( |
| [ |
| DataElement.sequence( |
| [ |
| DataElement.uuid(BT_L2CAP_PROTOCOL_ID), |
| DataElement.unsigned_integer_16(AVDTP_PSM), |
| ] |
| ), |
| DataElement.sequence( |
| [ |
| DataElement.uuid(BT_AVDTP_PROTOCOL_ID), |
| DataElement.unsigned_integer_16(version_int), |
| ] |
| ), |
| ] |
| ), |
| ), |
| ServiceAttribute( |
| SDP_BLUETOOTH_PROFILE_DESCRIPTOR_LIST_ATTRIBUTE_ID, |
| DataElement.sequence( |
| [ |
| DataElement.uuid(BT_ADVANCED_AUDIO_DISTRIBUTION_SERVICE), |
| DataElement.unsigned_integer_16(version_int), |
| ] |
| ), |
| ), |
| ] |
| |
| |
| # ----------------------------------------------------------------------------- |
| def make_audio_sink_service_sdp_records(service_record_handle, version=(1, 3)): |
| # pylint: disable=import-outside-toplevel |
| from .avdtp import AVDTP_PSM |
| |
| version_int = version[0] << 8 | version[1] |
| return [ |
| ServiceAttribute( |
| SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID, |
| DataElement.unsigned_integer_32(service_record_handle), |
| ), |
| ServiceAttribute( |
| SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID, |
| DataElement.sequence([DataElement.uuid(SDP_PUBLIC_BROWSE_ROOT)]), |
| ), |
| ServiceAttribute( |
| SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID, |
| DataElement.sequence([DataElement.uuid(BT_AUDIO_SINK_SERVICE)]), |
| ), |
| ServiceAttribute( |
| SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID, |
| DataElement.sequence( |
| [ |
| DataElement.sequence( |
| [ |
| DataElement.uuid(BT_L2CAP_PROTOCOL_ID), |
| DataElement.unsigned_integer_16(AVDTP_PSM), |
| ] |
| ), |
| DataElement.sequence( |
| [ |
| DataElement.uuid(BT_AVDTP_PROTOCOL_ID), |
| DataElement.unsigned_integer_16(version_int), |
| ] |
| ), |
| ] |
| ), |
| ), |
| ServiceAttribute( |
| SDP_BLUETOOTH_PROFILE_DESCRIPTOR_LIST_ATTRIBUTE_ID, |
| DataElement.sequence( |
| [ |
| DataElement.uuid(BT_ADVANCED_AUDIO_DISTRIBUTION_SERVICE), |
| DataElement.unsigned_integer_16(version_int), |
| ] |
| ), |
| ), |
| ] |
| |
| |
| # ----------------------------------------------------------------------------- |
| class SbcMediaCodecInformation( |
| namedtuple( |
| 'SbcMediaCodecInformation', |
| [ |
| 'sampling_frequency', |
| 'channel_mode', |
| 'block_length', |
| 'subbands', |
| 'allocation_method', |
| 'minimum_bitpool_value', |
| 'maximum_bitpool_value', |
| ], |
| ) |
| ): |
| ''' |
| A2DP spec - 4.3.2 Codec Specific Information Elements |
| ''' |
| |
| BIT_FIELDS = 'u4u4u4u2u2u8u8' |
| SAMPLING_FREQUENCY_BITS = {16000: 1 << 3, 32000: 1 << 2, 44100: 1 << 1, 48000: 1} |
| CHANNEL_MODE_BITS = { |
| SBC_MONO_CHANNEL_MODE: 1 << 3, |
| SBC_DUAL_CHANNEL_MODE: 1 << 2, |
| SBC_STEREO_CHANNEL_MODE: 1 << 1, |
| SBC_JOINT_STEREO_CHANNEL_MODE: 1, |
| } |
| BLOCK_LENGTH_BITS = {4: 1 << 3, 8: 1 << 2, 12: 1 << 1, 16: 1} |
| SUBBANDS_BITS = {4: 1 << 1, 8: 1} |
| ALLOCATION_METHOD_BITS = { |
| SBC_SNR_ALLOCATION_METHOD: 1 << 1, |
| SBC_LOUDNESS_ALLOCATION_METHOD: 1, |
| } |
| |
| @staticmethod |
| def from_bytes(data): |
| return SbcMediaCodecInformation( |
| *bitstruct.unpack(SbcMediaCodecInformation.BIT_FIELDS, data) |
| ) |
| |
| @classmethod |
| def from_discrete_values( |
| cls, |
| sampling_frequency, |
| channel_mode, |
| block_length, |
| subbands, |
| allocation_method, |
| minimum_bitpool_value, |
| maximum_bitpool_value, |
| ): |
| return SbcMediaCodecInformation( |
| sampling_frequency=cls.SAMPLING_FREQUENCY_BITS[sampling_frequency], |
| channel_mode=cls.CHANNEL_MODE_BITS[channel_mode], |
| block_length=cls.BLOCK_LENGTH_BITS[block_length], |
| subbands=cls.SUBBANDS_BITS[subbands], |
| allocation_method=cls.ALLOCATION_METHOD_BITS[allocation_method], |
| minimum_bitpool_value=minimum_bitpool_value, |
| maximum_bitpool_value=maximum_bitpool_value, |
| ) |
| |
| @classmethod |
| def from_lists( |
| cls, |
| sampling_frequencies, |
| channel_modes, |
| block_lengths, |
| subbands, |
| allocation_methods, |
| minimum_bitpool_value, |
| maximum_bitpool_value, |
| ): |
| return SbcMediaCodecInformation( |
| sampling_frequency=sum( |
| cls.SAMPLING_FREQUENCY_BITS[x] for x in sampling_frequencies |
| ), |
| channel_mode=sum(cls.CHANNEL_MODE_BITS[x] for x in channel_modes), |
| block_length=sum(cls.BLOCK_LENGTH_BITS[x] for x in block_lengths), |
| subbands=sum(cls.SUBBANDS_BITS[x] for x in subbands), |
| allocation_method=sum( |
| cls.ALLOCATION_METHOD_BITS[x] for x in allocation_methods |
| ), |
| minimum_bitpool_value=minimum_bitpool_value, |
| maximum_bitpool_value=maximum_bitpool_value, |
| ) |
| |
| def __bytes__(self): |
| return bitstruct.pack(self.BIT_FIELDS, *self) |
| |
| def __str__(self): |
| channel_modes = ['MONO', 'DUAL_CHANNEL', 'STEREO', 'JOINT_STEREO'] |
| allocation_methods = ['SNR', 'Loudness'] |
| return '\n'.join( |
| # pylint: disable=line-too-long |
| [ |
| 'SbcMediaCodecInformation(', |
| f' sampling_frequency: {",".join([str(x) for x in flags_to_list(self.sampling_frequency, SBC_SAMPLING_FREQUENCIES)])}', |
| f' channel_mode: {",".join([str(x) for x in flags_to_list(self.channel_mode, channel_modes)])}', |
| f' block_length: {",".join([str(x) for x in flags_to_list(self.block_length, SBC_BLOCK_LENGTHS)])}', |
| f' subbands: {",".join([str(x) for x in flags_to_list(self.subbands, SBC_SUBBANDS)])}', |
| f' allocation_method: {",".join([str(x) for x in flags_to_list(self.allocation_method, allocation_methods)])}', |
| f' minimum_bitpool_value: {self.minimum_bitpool_value}', |
| f' maximum_bitpool_value: {self.maximum_bitpool_value}' ')', |
| ] |
| ) |
| |
| |
| # ----------------------------------------------------------------------------- |
| class AacMediaCodecInformation( |
| namedtuple( |
| 'AacMediaCodecInformation', |
| ['object_type', 'sampling_frequency', 'channels', 'vbr', 'bitrate'], |
| ) |
| ): |
| ''' |
| A2DP spec - 4.5.2 Codec Specific Information Elements |
| ''' |
| |
| BIT_FIELDS = 'u8u12u2p2u1u23' |
| OBJECT_TYPE_BITS = { |
| MPEG_2_AAC_LC_OBJECT_TYPE: 1 << 7, |
| MPEG_4_AAC_LC_OBJECT_TYPE: 1 << 6, |
| MPEG_4_AAC_LTP_OBJECT_TYPE: 1 << 5, |
| MPEG_4_AAC_SCALABLE_OBJECT_TYPE: 1 << 4, |
| } |
| SAMPLING_FREQUENCY_BITS = { |
| 8000: 1 << 11, |
| 11025: 1 << 10, |
| 12000: 1 << 9, |
| 16000: 1 << 8, |
| 22050: 1 << 7, |
| 24000: 1 << 6, |
| 32000: 1 << 5, |
| 44100: 1 << 4, |
| 48000: 1 << 3, |
| 64000: 1 << 2, |
| 88200: 1 << 1, |
| 96000: 1, |
| } |
| CHANNELS_BITS = {1: 1 << 1, 2: 1} |
| |
| @staticmethod |
| def from_bytes(data): |
| return AacMediaCodecInformation( |
| *bitstruct.unpack(AacMediaCodecInformation.BIT_FIELDS, data) |
| ) |
| |
| @classmethod |
| def from_discrete_values( |
| cls, object_type, sampling_frequency, channels, vbr, bitrate |
| ): |
| return AacMediaCodecInformation( |
| object_type=cls.OBJECT_TYPE_BITS[object_type], |
| sampling_frequency=cls.SAMPLING_FREQUENCY_BITS[sampling_frequency], |
| channels=cls.CHANNELS_BITS[channels], |
| vbr=vbr, |
| bitrate=bitrate, |
| ) |
| |
| @classmethod |
| def from_lists(cls, object_types, sampling_frequencies, channels, vbr, bitrate): |
| return AacMediaCodecInformation( |
| object_type=sum(cls.OBJECT_TYPE_BITS[x] for x in object_types), |
| sampling_frequency=sum( |
| cls.SAMPLING_FREQUENCY_BITS[x] for x in sampling_frequencies |
| ), |
| channels=sum(cls.CHANNELS_BITS[x] for x in channels), |
| vbr=vbr, |
| bitrate=bitrate, |
| ) |
| |
| def __bytes__(self): |
| return bitstruct.pack(self.BIT_FIELDS, *self) |
| |
| def __str__(self): |
| object_types = [ |
| 'MPEG_2_AAC_LC', |
| 'MPEG_4_AAC_LC', |
| 'MPEG_4_AAC_LTP', |
| 'MPEG_4_AAC_SCALABLE', |
| '[4]', |
| '[5]', |
| '[6]', |
| '[7]', |
| ] |
| channels = [1, 2] |
| # pylint: disable=line-too-long |
| return '\n'.join( |
| [ |
| 'AacMediaCodecInformation(', |
| f' object_type: {",".join([str(x) for x in flags_to_list(self.object_type, object_types)])}', |
| f' sampling_frequency: {",".join([str(x) for x in flags_to_list(self.sampling_frequency, MPEG_2_4_AAC_SAMPLING_FREQUENCIES)])}', |
| f' channels: {",".join([str(x) for x in flags_to_list(self.channels, channels)])}', |
| f' vbr: {self.vbr}', |
| f' bitrate: {self.bitrate}' ')', |
| ] |
| ) |
| |
| |
| # ----------------------------------------------------------------------------- |
| class VendorSpecificMediaCodecInformation: |
| ''' |
| A2DP spec - 4.7.2 Codec Specific Information Elements |
| ''' |
| |
| @staticmethod |
| def from_bytes(data): |
| (vendor_id, codec_id) = struct.unpack_from('<IH', data, 0) |
| return VendorSpecificMediaCodecInformation(vendor_id, codec_id, data[6:]) |
| |
| def __init__(self, vendor_id, codec_id, value): |
| self.vendor_id = vendor_id |
| self.codec_id = codec_id |
| self.value = value |
| |
| def __bytes__(self): |
| return struct.pack('<IH', self.vendor_id, self.codec_id, self.value) |
| |
| def __str__(self): |
| # pylint: disable=line-too-long |
| return '\n'.join( |
| [ |
| 'VendorSpecificMediaCodecInformation(', |
| f' vendor_id: {self.vendor_id:08X} ({name_or_number(COMPANY_IDENTIFIERS, self.vendor_id & 0xFFFF)})', |
| f' codec_id: {self.codec_id:04X}', |
| f' value: {self.value.hex()}' ')', |
| ] |
| ) |
| |
| |
| # ----------------------------------------------------------------------------- |
| class SbcFrame: |
| def __init__( |
| self, sampling_frequency, block_count, channel_mode, subband_count, payload |
| ): |
| self.sampling_frequency = sampling_frequency |
| self.block_count = block_count |
| self.channel_mode = channel_mode |
| self.subband_count = subband_count |
| self.payload = payload |
| |
| @property |
| def sample_count(self): |
| return self.subband_count * self.block_count |
| |
| @property |
| def bitrate(self): |
| return 8 * ((len(self.payload) * self.sampling_frequency) // self.sample_count) |
| |
| @property |
| def duration(self): |
| return self.sample_count / self.sampling_frequency |
| |
| def __str__(self): |
| return ( |
| f'SBC(sf={self.sampling_frequency},' |
| f'cm={self.channel_mode},' |
| f'br={self.bitrate},' |
| f'sc={self.sample_count},' |
| f'size={len(self.payload)})' |
| ) |
| |
| |
| # ----------------------------------------------------------------------------- |
| class SbcParser: |
| def __init__(self, read): |
| self.read = read |
| |
| @property |
| def frames(self): |
| async def generate_frames(): |
| while True: |
| # Read 4 bytes of header |
| header = await self.read(4) |
| if len(header) != 4: |
| return |
| |
| # Check the sync word |
| if header[0] != SBC_SYNC_WORD: |
| logger.debug('invalid sync word') |
| return |
| |
| # Extract some of the header fields |
| sampling_frequency = SBC_SAMPLING_FREQUENCIES[(header[1] >> 6) & 3] |
| blocks = 4 * (1 + ((header[1] >> 4) & 3)) |
| channel_mode = (header[1] >> 2) & 3 |
| channels = 1 if channel_mode == SBC_MONO_CHANNEL_MODE else 2 |
| subbands = 8 if ((header[1]) & 1) else 4 |
| bitpool = header[2] |
| |
| # Compute the frame length |
| frame_length = 4 + (4 * subbands * channels) // 8 |
| if channel_mode in (SBC_MONO_CHANNEL_MODE, SBC_DUAL_CHANNEL_MODE): |
| frame_length += (blocks * channels * bitpool) // 8 |
| else: |
| frame_length += ( |
| (1 if channel_mode == SBC_JOINT_STEREO_CHANNEL_MODE else 0) |
| * subbands |
| + blocks * bitpool |
| ) // 8 |
| |
| # Read the rest of the frame |
| payload = header + await self.read(frame_length - 4) |
| |
| # Emit the next frame |
| yield SbcFrame( |
| sampling_frequency, blocks, channel_mode, subbands, payload |
| ) |
| |
| return generate_frames() |
| |
| |
| # ----------------------------------------------------------------------------- |
| class SbcPacketSource: |
| def __init__(self, read, mtu, codec_capabilities): |
| self.read = read |
| self.mtu = mtu |
| self.codec_capabilities = codec_capabilities |
| |
| @property |
| def packets(self): |
| async def generate_packets(): |
| # pylint: disable=import-outside-toplevel |
| from .avdtp import MediaPacket # Import here to avoid a circular reference |
| |
| sequence_number = 0 |
| timestamp = 0 |
| frames = [] |
| frames_size = 0 |
| max_rtp_payload = self.mtu - 12 - 1 |
| |
| # NOTE: this doesn't support frame fragments |
| sbc_parser = SbcParser(self.read) |
| async for frame in sbc_parser.frames: |
| print(frame) |
| |
| if ( |
| frames_size + len(frame.payload) > max_rtp_payload |
| or len(frames) == 16 |
| ): |
| # Need to flush what has been accumulated so far |
| |
| # Emit a packet |
| sbc_payload = bytes([len(frames)]) + b''.join( |
| [frame.payload for frame in frames] |
| ) |
| packet = MediaPacket( |
| 2, 0, 0, 0, sequence_number, timestamp, 0, [], 96, sbc_payload |
| ) |
| packet.timestamp_seconds = timestamp / frame.sampling_frequency |
| yield packet |
| |
| # Prepare for next packets |
| sequence_number += 1 |
| timestamp += sum((frame.sample_count for frame in frames)) |
| frames = [frame] |
| frames_size = len(frame.payload) |
| else: |
| # Accumulate |
| frames.append(frame) |
| frames_size += len(frame.payload) |
| |
| return generate_packets() |
