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temp fix: soxr dithering overflow #421

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temp fix: soxr dithering overflow #421

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14 changes: 13 additions & 1 deletion livekit-rtc/livekit/rtc/audio_resampler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,8 @@
from ._utils import get_address
from .audio_frame import AudioFrame

import numpy as np


@unique
class AudioResamplerQuality(str, Enum):
Expand Down Expand Up @@ -95,9 +97,18 @@ def push(self, data: bytearray | AudioFrame) -> list[AudioFrame]:
"""
bdata = data if isinstance(data, bytearray) else data.data.cast("b")

# temp fix:
# define DITHERING + (1./32)*(int)(((ran1>>3)&31)-((ran2>>3)&31)
# soxr dithering seems to overflow the int16 range (it's unclear why it happens on our builds
# but not inside the soxr lib)
audio_array = np.frombuffer(bdata, dtype=np.int16).astype(np.float32)
scaled_int16 = (audio_array * 0.9).astype(np.int16)

audio_view = memoryview(scaled_int16)

req = proto_ffi.FfiRequest()
req.push_sox_resampler.resampler_handle = self._ffi_handle.handle
req.push_sox_resampler.data_ptr = get_address(memoryview(bdata))
req.push_sox_resampler.data_ptr = get_address(audio_view)
req.push_sox_resampler.size = len(bdata)

resp = FfiClient.instance.request(req)
Expand All @@ -111,6 +122,7 @@ def push(self, data: bytearray | AudioFrame) -> list[AudioFrame]:
cdata = (ctypes.c_int8 * resp.push_sox_resampler.size).from_address(
resp.push_sox_resampler.output_ptr
)

output_data = bytearray(cdata)
return [
AudioFrame(
Expand Down
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