func NewEncoder(sampleRate, channels int, application Application) (*Encoder, error) {
encoder := &Encoder{}
encoder.data = make([]byte, int(C.opus_encoder_get_size(C.int(channels))))
encoder.cEncoder = (*C.struct_OpusEncoder)(unsafe.Pointer(&encoder.data[0]))
ret := C.opus_encoder_init(encoder.cEncoder, C.opus_int32(sampleRate), C.int(channels), C.int(application))
if err := getErr(ret); err != nil {
return nil, err
}
return encoder, nil
}
func (this *Encoder) Init(sampleRate int, channels int, application Application) {
C.opus_encoder_init(
this.ptr,
C.opus_int32(C.int(sampleRate)),
C.int(channels),
C.int(application),
)
}
// Allocates and initializes an encoder state. There are three coding modes:
//
// 1. APPLICATION_VOIP gives best quality at a given bitrate for voice
// signals. It enhances the input signal by high-pass filtering and
// emphasizing formants and harmonics. Optionally it includes in-band forward
// error correction to protect against packet loss. Use this mode for typical
// VoIP applications. Because of the enhancement, even at high bitrates the
// output may sound different from the input.
//
// 2. APPLICATION_AUDIO gives best quality at a given bitrate for most
// non-voice signals like music. Use this mode for music and mixed
// (music/voice) content, broadcast, and applications requiring less than 15
// ms of coding delay.
//
// 3. APPLICATION_RESTRICTED_LOWDELAY configures low-delay mode that disables
// the speech-optimized mode in exchange for slightly reduced delay. This mode
// can only be set on an newly initialized or freshly reset encoder because it
// changes the codec delay. This is useful when the caller knows that the
// speech-optimized modes will not be needed (use with caution).
//
// Fs: Sampling rate of input signal (Hz). This must be one of 8000, 12000,
// 16000, 24000, or 48000.
//
// channels: Number of channels (1 or 2) in input signal
//
// application: Coding mode (APPLICATION_VOIP/APPLICATION_AUDIO/APPLICATION_RESTRICTED_LOWDELAY)
//
// note: Regardless of the sampling rate and number channels selected, the Opus
// encoder can switch to a lower audio bandwidth or number of channels if the
// bitrate selected is too low. This also means that it is safe to always use
// 48 kHz stereo input and let the encoder optimize the encoding.
func NewEncoder(Fs, channels, application int) (*Encoder, error) {
enc := new(Encoder)
err := opusError(C.opus_encoder_init(
enc.cptr(),
C.opus_int32(Fs),
C.int(channels),
C.int(application),
))
if err != nil {
return nil, err
}
return enc, nil
}
// Init initializes a pre-allocated opus encoder. Unless the encoder has been
// created using NewEncoder, this method must be called exactly once in the
// life-time of this object, before calling any other methods.
func (enc *Encoder) Init(sample_rate int, channels int, application Application) error {
if enc.p != nil {
return fmt.Errorf("opus encoder already initialized")
}
if channels != 1 && channels != 2 {
return fmt.Errorf("Number of channels must be 1 or 2: %d", channels)
}
size := C.opus_encoder_get_size(C.int(channels))
enc.mem = make([]byte, size)
enc.p = (*C.OpusEncoder)(unsafe.Pointer(&enc.mem[0]))
errno := int(C.opus_encoder_init(
enc.p,
C.opus_int32(sample_rate),
C.int(channels),
C.int(application)))
if errno != 0 {
return opuserr(int(errno))
}
return nil
}