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Merged
asoulier merged 1 commit into from
May 23, 2025
Merged

python: Add PLC interface for the python wrapper #75

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34 changes: 21 additions & 13 deletions python/lc3.py
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Original file line number Diff line number Diff line change
Expand Up @@ -472,21 +472,23 @@ def __del__(self) -> None:

@typing.overload
def decode(
self, data: bytes | bytearray | memoryview, bit_depth: None = None
self, data: bytes | bytearray | memoryview | None, bit_depth: None = None
) -> array.array[float]: ...

@typing.overload
def decode(self, data: bytes | bytearray | memoryview, bit_depth: int) -> bytes: ...
def decode(self, data: bytes | bytearray | memoryview | None, bit_depth: int) -> bytes: ...

def decode(
self, data: bytes | bytearray | memoryview, bit_depth: int | None = None
self, data: bytes | bytearray | memoryview | None, bit_depth: int | None = None
) -> bytes | array.array[float]:
"""
Decodes an LC3 frame.

The input `data` is the channels concatenation of LC3 frames in a
byte-like object. Interleaved PCM samples are returned according to
the `bit_depth` indication.
Setting `data` to `None` enables PLC (Packet Loss Concealment)
reconstruction for the block of LC3 frames.
When no `bit_depth` is defined, it's a vector of floating point values
from -1 to 1, coding the sample levels. When `bit_depth` is defined,
it returns a byte array, each sample coded on `bit_depth` bits.
Expand All @@ -500,22 +502,28 @@ def decode(
pcm_len = num_channels * self.get_frame_samples()
pcm_buffer = (pcm_t * pcm_len)()

data_buffer = bytearray(data)
data_offset = 0
if data is not None:
data_buffer = bytearray(data)
data_offset = 0

for ich, decoder in enumerate(self.__decoders):
pcm_offset = ich * ctypes.sizeof(pcm_t)
pcm = (pcm_t * (pcm_len - ich)).from_buffer(pcm_buffer, pcm_offset)

data_size = len(data_buffer) // num_channels + int(
ich < len(data_buffer) % num_channels
)
buf = (c_byte * data_size).from_buffer(data_buffer, data_offset)
data_offset += data_size
if data is None:
ret = self.lib.lc3_decode(
decoder, None, 0, pcm_fmt, pcm, self.num_channels
)
else:
data_size = len(data_buffer) // num_channels + int(
ich < len(data_buffer) % num_channels
)
buf = (c_byte * data_size).from_buffer(data_buffer, data_offset)
data_offset += data_size
ret = self.lib.lc3_decode(
decoder, buf, len(buf), pcm_fmt, pcm, self.num_channels
)

ret = self.lib.lc3_decode(
decoder, buf, len(buf), pcm_fmt, pcm, self.num_channels
)
if ret < 0:
raise InvalidArgumentError("Bad parameters")

Expand Down