internal unsafe PcmEncodingTranscoder(PipeReader input,
PcmAudioCodec codec)
{
const int Application = 2049; // OPUS_APPLICATION_AUDIO
Debug.Assert(
typeof(T) == typeof(short) ||
typeof(T) == typeof(float));
Debug.Assert(codec.ChannelCount == 2);
Debug.Assert(codec.SamplingRate == 48000);
_codec = codec;
int status;
_encoder = opus_encoder_create(codec.SamplingRate,
codec.ChannelCount, Application, &status);
if (status < 0)
{
ThrowExternalException("Could not create Opus Encoder",
status);
}
_input = input;
_pipe = new Pipe();
}
static unsafe int WriteInternal(OpusEncoder *encoder,
int channelCount, ReadOnlySpan <byte> frame, PipeWriter writer)
{
var block = writer.GetSpan();
int frameSize = frame.Length / sizeof(T) / channelCount;
int encoded = default;
fixed(byte *sampleData = frame)
fixed(byte *outputBlock = block.Slice(2))
if (typeof(T) == typeof(short))
{
encoded = opus_encode(encoder, (short *)sampleData,
frameSize, outputBlock, block.Length);
}
else if (typeof(T) == typeof(float))
{
encoded = opus_encode_float(encoder,
(float *)sampleData, frameSize, outputBlock,
block.Length);
}
return(encoded > 0 &&
!BinaryPrimitives.TryWriteInt16LittleEndian(block,
(short)encoded)
? -1
: encoded);
}
public static extern int opus_encoder_ctl([NativeTypeName("OpusEncoder *")] OpusEncoder *st, int request);
public static extern void opus_encoder_destroy([NativeTypeName("OpusEncoder *")] OpusEncoder *st);
public static extern int opus_encode_float([NativeTypeName("OpusEncoder *")] OpusEncoder *st, [NativeTypeName("const float *")] float *pcm, int frame_size, [NativeTypeName("unsigned char *")] byte *data, [NativeTypeName("opus_int32")] int max_data_bytes);
public static extern int opus_encoder_init([NativeTypeName("OpusEncoder *")] OpusEncoder *st, [NativeTypeName("opus_int32")] int Fs, int channels, int application);
