openCom-Companion/sbapp/pyogg/opus_file.py

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2024-06-03 01:54:58 +02:00
import ctypes
from . import ogg
from . import opus
from .pyogg_error import PyOggError
from .audio_file import AudioFile
class OpusFile(AudioFile):
def __init__(self, path: str) -> None:
# Open the file
error = ctypes.c_int()
of = opus.op_open_file(
ogg.to_char_p(path),
ctypes.pointer(error)
)
# Check for errors
if error.value != 0:
raise PyOggError(
("File '{}' couldn't be opened or doesn't exist. "+
"Error code: {}").format(path, error.value)
)
# Extract the number of channels in the newly opened file
#: Number of channels in audio file.
self.channels = opus.op_channel_count(of, -1)
# Allocate sufficient memory to store the entire PCM
pcm_size = opus.op_pcm_total(of, -1)
Buf = opus.opus_int16*(pcm_size*self.channels)
buf = Buf()
# Create a pointer to the newly allocated memory. It
# seems we can only do pointer arithmetic on void
# pointers. See
# https://mattgwwalker.wordpress.com/2020/05/30/pointer-manipulation-in-python/
buf_ptr = ctypes.cast(
ctypes.pointer(buf),
ctypes.c_void_p
)
assert buf_ptr.value is not None # for mypy
buf_ptr_zero = buf_ptr.value
#: Bytes per sample
self.bytes_per_sample = ctypes.sizeof(opus.opus_int16)
# Read through the entire file, copying the PCM into the
# buffer
samples = 0
while True:
# Calculate remaining buffer size
remaining_buffer = (
len(buf) # int
- (buf_ptr.value
- buf_ptr_zero) // self.bytes_per_sample
)
# Convert buffer pointer to the desired type
ptr = ctypes.cast(
buf_ptr,
ctypes.POINTER(opus.opus_int16)
)
# Read the next section of PCM
ns = opus.op_read(
of,
ptr,
remaining_buffer,
ogg.c_int_p()
)
# Check for errors
if ns<0:
raise PyOggError(
"Error while reading OggOpus file. "+
"Error code: {}".format(ns)
)
# Increment the pointer
buf_ptr.value += (
ns
* self.bytes_per_sample
* self.channels
)
assert buf_ptr.value is not None # for mypy
samples += ns
# Check if we've finished
if ns==0:
break
# Close the open file
opus.op_free(of)
# Opus files are always stored at 48k samples per second
#: Number of samples per second (per channel). Always 48,000.
self.frequency = 48000
# Cast buffer to a one-dimensional array of chars
#: Raw PCM data from audio file.
CharBuffer = (
ctypes.c_byte
* (self.bytes_per_sample * self.channels * pcm_size)
)
self.buffer = CharBuffer.from_buffer(buf)