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bumble_fork/bumble/a2dp.py
Gilles Boccon-Gibod 7aba36302a use isort when formatting
2025-08-21 16:38:58 -07:00

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# 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
# -----------------------------------------------------------------------------
from __future__ import annotations
import dataclasses
import enum
import logging
import struct
from collections.abc import AsyncGenerator
from typing import Awaitable, Callable
from typing_extensions import ClassVar, Self
from bumble.codecs import AacAudioRtpPacket
from bumble.company_ids import COMPANY_IDENTIFIERS
from bumble.core import (
BT_ADVANCED_AUDIO_DISTRIBUTION_SERVICE,
BT_AUDIO_SINK_SERVICE,
BT_AUDIO_SOURCE_SERVICE,
BT_AVDTP_PROTOCOL_ID,
BT_L2CAP_PROTOCOL_ID,
name_or_number,
)
from bumble.rtp import MediaPacket
from bumble.sdp import (
SDP_BLUETOOTH_PROFILE_DESCRIPTOR_LIST_ATTRIBUTE_ID,
SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID,
SDP_PROTOCOL_DESCRIPTOR_LIST_ATTRIBUTE_ID,
SDP_PUBLIC_BROWSE_ROOT,
SDP_SERVICE_CLASS_ID_LIST_ATTRIBUTE_ID,
SDP_SERVICE_RECORD_HANDLE_ATTRIBUTE_ID,
DataElement,
ServiceAttribute,
)
# -----------------------------------------------------------------------------
# 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'
}
SBC_MAX_FRAMES_IN_RTP_PAYLOAD = 15
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'
}
OPUS_MAX_FRAMES_IN_RTP_PAYLOAD = 15
# 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 bumble.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.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 bumble.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.sequence(
[
DataElement.uuid(BT_ADVANCED_AUDIO_DISTRIBUTION_SERVICE),
DataElement.unsigned_integer_16(version_int),
]
)
]
),
),
]
# -----------------------------------------------------------------------------
@dataclasses.dataclass
class SbcMediaCodecInformation:
'''
A2DP spec - 4.3.2 Codec Specific Information Elements
'''
sampling_frequency: SamplingFrequency
channel_mode: ChannelMode
block_length: BlockLength
subbands: Subbands
allocation_method: AllocationMethod
minimum_bitpool_value: int
maximum_bitpool_value: int
class SamplingFrequency(enum.IntFlag):
SF_16000 = 1 << 3
SF_32000 = 1 << 2
SF_44100 = 1 << 1
SF_48000 = 1 << 0
@classmethod
def from_int(cls, sampling_frequency: int) -> Self:
sampling_frequencies = [
16000,
32000,
44100,
48000,
]
index = sampling_frequencies.index(sampling_frequency)
return cls(1 << (len(sampling_frequencies) - index - 1))
class ChannelMode(enum.IntFlag):
MONO = 1 << 3
DUAL_CHANNEL = 1 << 2
STEREO = 1 << 1
JOINT_STEREO = 1 << 0
class BlockLength(enum.IntFlag):
BL_4 = 1 << 3
BL_8 = 1 << 2
BL_12 = 1 << 1
BL_16 = 1 << 0
class Subbands(enum.IntFlag):
S_4 = 1 << 1
S_8 = 1 << 0
class AllocationMethod(enum.IntFlag):
SNR = 1 << 1
LOUDNESS = 1 << 0
@classmethod
def from_bytes(cls, data: bytes) -> Self:
sampling_frequency = cls.SamplingFrequency((data[0] >> 4) & 0x0F)
channel_mode = cls.ChannelMode((data[0] >> 0) & 0x0F)
block_length = cls.BlockLength((data[1] >> 4) & 0x0F)
subbands = cls.Subbands((data[1] >> 2) & 0x03)
allocation_method = cls.AllocationMethod((data[1] >> 0) & 0x03)
minimum_bitpool_value = (data[2] >> 0) & 0xFF
maximum_bitpool_value = (data[3] >> 0) & 0xFF
return cls(
sampling_frequency,
channel_mode,
block_length,
subbands,
allocation_method,
minimum_bitpool_value,
maximum_bitpool_value,
)
def __bytes__(self) -> bytes:
return bytes(
[
(self.sampling_frequency << 4) | self.channel_mode,
(self.block_length << 4)
| (self.subbands << 2)
| self.allocation_method,
self.minimum_bitpool_value,
self.maximum_bitpool_value,
]
)
# -----------------------------------------------------------------------------
@dataclasses.dataclass
class AacMediaCodecInformation:
'''
A2DP spec - 4.5.2 Codec Specific Information Elements
'''
object_type: ObjectType
sampling_frequency: SamplingFrequency
channels: Channels
vbr: int
bitrate: int
class ObjectType(enum.IntFlag):
MPEG_2_AAC_LC = 1 << 7
MPEG_4_AAC_LC = 1 << 6
MPEG_4_AAC_LTP = 1 << 5
MPEG_4_AAC_SCALABLE = 1 << 4
class SamplingFrequency(enum.IntFlag):
SF_8000 = 1 << 11
SF_11025 = 1 << 10
SF_12000 = 1 << 9
SF_16000 = 1 << 8
SF_22050 = 1 << 7
SF_24000 = 1 << 6
SF_32000 = 1 << 5
SF_44100 = 1 << 4
SF_48000 = 1 << 3
SF_64000 = 1 << 2
SF_88200 = 1 << 1
SF_96000 = 1 << 0
@classmethod
def from_int(cls, sampling_frequency: int) -> Self:
sampling_frequencies = [
8000,
11025,
12000,
16000,
22050,
24000,
32000,
44100,
48000,
64000,
88200,
96000,
]
index = sampling_frequencies.index(sampling_frequency)
return cls(1 << (len(sampling_frequencies) - index - 1))
class Channels(enum.IntFlag):
MONO = 1 << 1
STEREO = 1 << 0
@classmethod
def from_bytes(cls, data: bytes) -> AacMediaCodecInformation:
object_type = cls.ObjectType(data[0])
sampling_frequency = cls.SamplingFrequency(
(data[1] << 4) | ((data[2] >> 4) & 0x0F)
)
channels = cls.Channels((data[2] >> 2) & 0x03)
vbr = (data[3] >> 7) & 0x01
bitrate = ((data[3] & 0x7F) << 16) | (data[4] << 8) | data[5]
return AacMediaCodecInformation(
object_type, sampling_frequency, channels, vbr, bitrate
)
def __bytes__(self) -> bytes:
return bytes(
[
self.object_type & 0xFF,
(self.sampling_frequency >> 4) & 0xFF,
(((self.sampling_frequency & 0x0F) << 4) | (self.channels << 2)) & 0xFF,
((self.vbr << 7) | ((self.bitrate >> 16) & 0x7F)) & 0xFF,
((self.bitrate >> 8) & 0xFF) & 0xFF,
self.bitrate & 0xFF,
]
)
@dataclasses.dataclass
# -----------------------------------------------------------------------------
class VendorSpecificMediaCodecInformation:
'''
A2DP spec - 4.7.2 Codec Specific Information Elements
'''
vendor_id: int
codec_id: int
value: bytes
@staticmethod
def from_bytes(data: bytes) -> VendorSpecificMediaCodecInformation:
(vendor_id, codec_id) = struct.unpack_from('<IH', data, 0)
return VendorSpecificMediaCodecInformation(vendor_id, codec_id, data[6:])
def __bytes__(self) -> bytes:
return struct.pack('<IH', self.vendor_id, self.codec_id) + self.value
def __str__(self) -> str:
# 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()}' ')',
]
)
# -----------------------------------------------------------------------------
@dataclasses.dataclass
class OpusMediaCodecInformation(VendorSpecificMediaCodecInformation):
vendor_id: int = dataclasses.field(init=False, repr=False)
codec_id: int = dataclasses.field(init=False, repr=False)
value: bytes = dataclasses.field(init=False, repr=False)
channel_mode: ChannelMode
frame_size: FrameSize
sampling_frequency: SamplingFrequency
class ChannelMode(enum.IntFlag):
MONO = 1 << 0
STEREO = 1 << 1
DUAL_MONO = 1 << 2
class FrameSize(enum.IntFlag):
FS_10MS = 1 << 0
FS_20MS = 1 << 1
class SamplingFrequency(enum.IntFlag):
SF_48000 = 1 << 0
@classmethod
def from_int(cls, sampling_frequency: int) -> Self:
if sampling_frequency != 48000:
raise ValueError("no such sampling frequency")
return cls(1)
VENDOR_ID: ClassVar[int] = 0x000000E0
CODEC_ID: ClassVar[int] = 0x0001
def __post_init__(self) -> None:
self.vendor_id = self.VENDOR_ID
self.codec_id = self.CODEC_ID
self.value = bytes(
[
self.channel_mode
| (self.frame_size << 3)
| (self.sampling_frequency << 7)
]
)
@classmethod
def from_bytes(cls, data: bytes) -> Self:
"""Create a new instance from the `value` part of the data, not including
the vendor id and codec id"""
channel_mode = cls.ChannelMode(data[0] & 0x07)
frame_size = cls.FrameSize((data[0] >> 3) & 0x03)
sampling_frequency = cls.SamplingFrequency((data[0] >> 7) & 0x01)
return cls(
channel_mode,
frame_size,
sampling_frequency,
)
def __str__(self) -> str:
return repr(self)
# -----------------------------------------------------------------------------
@dataclasses.dataclass
class SbcFrame:
sampling_frequency: int
block_count: int
channel_mode: int
allocation_method: int
subband_count: int
bitpool: int
payload: bytes
@property
def sample_count(self) -> int:
return self.subband_count * self.block_count
@property
def bitrate(self) -> int:
return 8 * ((len(self.payload) * self.sampling_frequency) // self.sample_count)
@property
def duration(self) -> float:
return self.sample_count / self.sampling_frequency
def __str__(self) -> str:
return (
f'SBC(sf={self.sampling_frequency},'
f'cm={self.channel_mode},'
f'am={self.allocation_method},'
f'br={self.bitrate},'
f'sc={self.sample_count},'
f'bp={self.bitpool},'
f'size={len(self.payload)})'
)
# -----------------------------------------------------------------------------
class SbcParser:
def __init__(self, read: Callable[[int], Awaitable[bytes]]) -> None:
self.read = read
@property
def frames(self) -> AsyncGenerator[SbcFrame, None]:
async def generate_frames() -> AsyncGenerator[SbcFrame, None]:
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
allocation_method = (header[1] >> 1) & 1
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,
allocation_method,
subbands,
bitpool,
payload,
)
return generate_frames()
# -----------------------------------------------------------------------------
class SbcPacketSource:
def __init__(self, read: Callable[[int], Awaitable[bytes]], mtu: int) -> None:
self.read = read
self.mtu = mtu
@property
def packets(self):
async def generate_packets():
sequence_number = 0
sample_count = 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:
if (
frames_size + len(frame.payload) > max_rtp_payload
or len(frames) == SBC_MAX_FRAMES_IN_RTP_PAYLOAD
):
# Need to flush what has been accumulated so far
logger.debug(f"yielding {len(frames)} frames")
# Emit a packet
sbc_payload = bytes([len(frames) & 0x0F]) + b''.join(
[frame.payload for frame in frames]
)
timestamp_seconds = sample_count / frame.sampling_frequency
timestamp = int(1000 * timestamp_seconds)
packet = MediaPacket(
2, 0, 0, 0, sequence_number, timestamp, 0, [], 96, sbc_payload
)
packet.timestamp_seconds = timestamp_seconds
yield packet
# Prepare for next packets
sequence_number += 1
sequence_number &= 0xFFFF
sample_count += 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()
# -----------------------------------------------------------------------------
@dataclasses.dataclass
class AacFrame:
class Profile(enum.IntEnum):
MAIN = 0
LC = 1
SSR = 2
LTP = 3
profile: Profile
sampling_frequency: int
channel_configuration: int
payload: bytes
@property
def sample_count(self) -> int:
return 1024
@property
def duration(self) -> float:
return self.sample_count / self.sampling_frequency
def __str__(self) -> str:
return (
f'AAC(sf={self.sampling_frequency},'
f'ch={self.channel_configuration},'
f'size={len(self.payload)})'
)
# -----------------------------------------------------------------------------
ADTS_AAC_SAMPLING_FREQUENCIES = [
96000,
88200,
64000,
48000,
44100,
32000,
24000,
22050,
16000,
12000,
11025,
8000,
7350,
0,
0,
0,
]
# -----------------------------------------------------------------------------
class AacParser:
"""Parser for AAC frames in an ADTS stream"""
def __init__(self, read: Callable[[int], Awaitable[bytes]]) -> None:
self.read = read
@property
def frames(self) -> AsyncGenerator[AacFrame, None]:
async def generate_frames() -> AsyncGenerator[AacFrame, None]:
while True:
header = await self.read(7)
if not header:
return
sync_word = (header[0] << 4) | (header[1] >> 4)
if sync_word != 0b111111111111:
raise ValueError(f"invalid sync word ({sync_word:06x})")
layer = (header[1] >> 1) & 0b11
profile = AacFrame.Profile((header[2] >> 6) & 0b11)
sampling_frequency = ADTS_AAC_SAMPLING_FREQUENCIES[
(header[2] >> 2) & 0b1111
]
channel_configuration = ((header[2] & 0b1) << 2) | (header[3] >> 6)
frame_length = (
((header[3] & 0b11) << 11) | (header[4] << 3) | (header[5] >> 5)
)
if layer != 0:
raise ValueError("layer must be 0")
payload = await self.read(frame_length - 7)
if payload:
yield AacFrame(
profile, sampling_frequency, channel_configuration, payload
)
return generate_frames()
# -----------------------------------------------------------------------------
class AacPacketSource:
def __init__(self, read: Callable[[int], Awaitable[bytes]], mtu: int) -> None:
self.read = read
self.mtu = mtu
@property
def packets(self):
async def generate_packets():
sequence_number = 0
sample_count = 0
aac_parser = AacParser(self.read)
async for frame in aac_parser.frames:
logger.debug("yielding one AAC frame")
# Emit a packet
aac_payload = bytes(
AacAudioRtpPacket.for_simple_aac(
frame.sampling_frequency,
frame.channel_configuration,
frame.payload,
)
)
timestamp_seconds = sample_count / frame.sampling_frequency
timestamp = int(1000 * timestamp_seconds)
packet = MediaPacket(
2, 0, 0, 0, sequence_number, timestamp, 0, [], 96, aac_payload
)
packet.timestamp_seconds = timestamp_seconds
yield packet
# Prepare for next packets
sequence_number += 1
sequence_number &= 0xFFFF
sample_count += frame.sample_count
return generate_packets()
# -----------------------------------------------------------------------------
@dataclasses.dataclass
class OpusPacket:
class ChannelMode(enum.IntEnum):
MONO = 0
STEREO = 1
DUAL_MONO = 2
channel_mode: ChannelMode
duration: int # Duration in ms.
sampling_frequency: int
payload: bytes
def __str__(self) -> str:
return (
f'Opus(ch={self.channel_mode.name}, '
f'd={self.duration}ms, '
f'size={len(self.payload)})'
)
# -----------------------------------------------------------------------------
class OpusParser:
"""
Parser for Opus packets in an Ogg stream
See RFC 3533
NOTE: this parser only supports bitstreams with a single logical stream.
"""
CAPTURE_PATTERN = b'OggS'
class HeaderType(enum.IntFlag):
CONTINUED = 0x01
FIRST = 0x02
LAST = 0x04
def __init__(self, read: Callable[[int], Awaitable[bytes]]) -> None:
self.read = read
@property
def packets(self) -> AsyncGenerator[OpusPacket, None]:
async def generate_frames() -> AsyncGenerator[OpusPacket, None]:
packet = b''
packet_count = 0
expected_bitstream_serial_number = None
expected_page_sequence_number = 0
channel_mode = OpusPacket.ChannelMode.STEREO
while True:
# Parse the page header
header = await self.read(27)
if len(header) != 27:
logger.debug("end of stream")
break
capture_pattern = header[:4]
if capture_pattern != self.CAPTURE_PATTERN:
print(capture_pattern.hex())
raise ValueError("invalid capture pattern at start of page")
version = header[4]
if version != 0:
raise ValueError(f"version {version} not supported")
header_type = self.HeaderType(header[5])
(
granule_position,
bitstream_serial_number,
page_sequence_number,
crc_checksum,
page_segments,
) = struct.unpack_from("<QIIIB", header, 6)
segment_table = await self.read(page_segments)
if header_type & self.HeaderType.FIRST:
if expected_bitstream_serial_number is None:
# We will only accept pages for the first encountered stream
logger.debug("BOS")
expected_bitstream_serial_number = bitstream_serial_number
expected_page_sequence_number = page_sequence_number
if (
expected_bitstream_serial_number is None
or expected_bitstream_serial_number != bitstream_serial_number
):
logger.debug("skipping page (not the first logical bitstream)")
for lacing_value in segment_table:
if lacing_value:
await self.read(lacing_value)
continue
if expected_page_sequence_number != page_sequence_number:
raise ValueError(
f"expected page sequence number {expected_page_sequence_number}"
f" but got {page_sequence_number}"
)
expected_page_sequence_number = page_sequence_number + 1
# Assemble the page
if not header_type & self.HeaderType.CONTINUED:
packet = b''
for lacing_value in segment_table:
if lacing_value:
packet += await self.read(lacing_value)
if lacing_value < 255:
# End of packet
packet_count += 1
if packet_count == 1:
# The first packet contains the identification header
logger.debug("first packet (header)")
if packet[:8] != b"OpusHead":
raise ValueError("first packet is not OpusHead")
packet_count = (
OpusPacket.ChannelMode.MONO
if packet[9] == 1
else OpusPacket.ChannelMode.STEREO
)
elif packet_count == 2:
# The second packet contains the comment header
logger.debug("second packet (tags)")
if packet[:8] != b"OpusTags":
logger.warning("second packet is not OpusTags")
else:
yield OpusPacket(channel_mode, 20, 48000, packet)
packet = b''
if header_type & self.HeaderType.LAST:
logger.debug("EOS")
return generate_frames()
# -----------------------------------------------------------------------------
class OpusPacketSource:
def __init__(self, read: Callable[[int], Awaitable[bytes]], mtu: int) -> None:
self.read = read
self.mtu = mtu
@property
def packets(self):
async def generate_packets():
sequence_number = 0
elapsed_ms = 0
opus_parser = OpusParser(self.read)
async for opus_packet in opus_parser.packets:
# We only support sending one Opus frame per RTP packet
# TODO: check the spec for the first byte value here
opus_payload = bytes([1]) + opus_packet.payload
elapsed_s = elapsed_ms / 1000
timestamp = int(elapsed_s * opus_packet.sampling_frequency)
rtp_packet = MediaPacket(
2, 0, 0, 0, sequence_number, timestamp, 0, [], 96, opus_payload
)
rtp_packet.timestamp_seconds = elapsed_s
yield rtp_packet
# Prepare for next packets
sequence_number += 1
sequence_number &= 0xFFFF
elapsed_ms += opus_packet.duration
return generate_packets()
# -----------------------------------------------------------------------------
# This map should be left at the end of the file so it can refer to the classes
# above
# -----------------------------------------------------------------------------
A2DP_VENDOR_MEDIA_CODEC_INFORMATION_CLASSES = {
OpusMediaCodecInformation.VENDOR_ID: {
OpusMediaCodecInformation.CODEC_ID: OpusMediaCodecInformation
}
}
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