File size: 6,303 Bytes
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import cython
import cython.cimports.libav as lib
from cython.cimports.av.error import err_check
class DeviceInfo:
"""Information about an input or output device.
:param str name: The device identifier, for use as the first argument to :func:`av.open`.
:param str description: Human-readable description of the device.
:param bool is_default: Whether this is the default device.
:param list media_types: Media types this device provides, e.g. ``["video"]``, ``["audio"]``,
or ``["video", "audio"]``.
"""
name: str
description: str
is_default: bool
media_types: list[str]
def __init__(
self,
name: str,
description: str,
is_default: bool,
media_types: list[str],
) -> None:
self.name = name
self.description = description
self.is_default = is_default
self.media_types = media_types
def __repr__(self) -> str:
default = " (default)" if self.is_default else ""
return f"<av.DeviceInfo {self.name!r} {self.description!r}{default}>"
@cython.cfunc
def _build_device_list(device_list: cython.pointer[lib.AVDeviceInfoList]) -> list:
devices: list = []
i: cython.int
j: cython.int
device_info: cython.pointer[lib.AVDeviceInfo]
mt: lib.AVMediaType
s: cython.p_const_char
for i in range(device_list.nb_devices):
device_info = device_list.devices[i]
media_types: list = []
for j in range(device_info.nb_media_types):
mt = device_info.media_types[j]
s = lib.av_get_media_type_string(mt)
if s:
media_types.append(s.decode())
devices.append(
DeviceInfo(
name=device_info.device_name.decode()
if device_info.device_name
else "",
description=device_info.device_description.decode()
if device_info.device_description
else "",
is_default=(i == device_list.default_device),
media_types=media_types,
)
)
return devices
def _enumerate_via_log_fallback(format_name: str) -> list[DeviceInfo]:
"""Fallback for formats (e.g. avfoundation) that log devices instead of
implementing get_device_list. Opens the format with list_devices=1 and
parses the INFO log output."""
from av import logging as avlogging
fmt: cython.pointer[cython.const[lib.AVInputFormat]] = lib.av_find_input_format(
format_name
)
opts: cython.pointer[lib.AVDictionary] = cython.NULL
lib.av_dict_set(cython.address(opts), b"list_devices", b"1", 0)
ctx: cython.pointer[lib.AVFormatContext] = cython.NULL
# Temporarily enable INFO logging so Capture receives device list messages.
old_level = avlogging.get_level()
avlogging.set_level(avlogging.INFO)
devices: list[DeviceInfo] = []
try:
with avlogging.Capture() as logs:
lib.avformat_open_input(cython.address(ctx), b"", fmt, cython.address(opts))
if ctx:
lib.avformat_close_input(cython.address(ctx))
current_media_type = "video"
for _level, _name, message in logs:
message = message.strip()
if "video devices" in message.lower():
current_media_type = "video"
elif "audio devices" in message.lower():
current_media_type = "audio"
else:
m = re.match(r"\[(\d+)\] (.+)", message)
if m:
devices.append(
DeviceInfo(
name=m.group(1),
description=m.group(2),
is_default=False,
media_types=[current_media_type],
)
)
finally:
avlogging.set_level(old_level)
lib.av_dict_free(cython.address(opts))
return devices
def enumerate_input_devices(format_name: str) -> list[DeviceInfo]:
"""List the available input devices for a given format.
:param str format_name: The format name, e.g. ``"avfoundation"``, ``"dshow"``, ``"v4l2"``.
:rtype: list[DeviceInfo]
:raises ValueError: If *format_name* is not a known input format.
:raises av.FFmpegError: If the device does not support enumeration.
Example::
for device in av.enumerate_input_devices("avfoundation"):
print(device.name, device.description)
"""
fmt: cython.pointer[cython.const[lib.AVInputFormat]] = lib.av_find_input_format(
format_name
)
if not fmt:
raise ValueError(f"no such input format: {format_name!r}")
device_list: cython.pointer[lib.AVDeviceInfoList] = cython.NULL
try:
err_check(
lib.avdevice_list_input_sources(
fmt, cython.NULL, cython.NULL, cython.address(device_list)
)
)
return _build_device_list(device_list)
except NotImplementedError:
# Format doesn't implement get_device_list (e.g. avfoundation).
# Fall back to opening with list_devices=1 and parsing the log output.
return _enumerate_via_log_fallback(format_name)
finally:
lib.avdevice_free_list_devices(cython.address(device_list))
def enumerate_output_devices(format_name: str) -> list[DeviceInfo]:
"""List the available output devices for a given format.
:param str format_name: The format name, e.g. ``"audiotoolbox"``.
:rtype: list[DeviceInfo]
:raises ValueError: If *format_name* is not a known output format.
:raises av.FFmpegError: If the device does not support enumeration.
"""
fmt: cython.pointer[cython.const[lib.AVOutputFormat]] = lib.av_guess_format(
format_name, cython.NULL, cython.NULL
)
if not fmt:
raise ValueError(f"no such output format: {format_name!r}")
device_list: cython.pointer[lib.AVDeviceInfoList] = cython.NULL
err_check(
lib.avdevice_list_output_sinks(
fmt, cython.NULL, cython.NULL, cython.address(device_list)
)
)
try:
return _build_device_list(device_list)
finally:
lib.avdevice_free_list_devices(cython.address(device_list))
|