263 lines
7.1 KiB
Go
263 lines
7.1 KiB
Go
// Copyright © Go Opus Authors (see AUTHORS file)
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//
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// License for use of this code is detailed in the LICENSE file
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package opus
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import (
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"fmt"
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"unsafe"
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)
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/*
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#cgo pkg-config: opus
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#include <opus.h>
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int
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bridge_decoder_get_last_packet_duration(OpusDecoder *st, opus_int32 *samples)
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{
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return opus_decoder_ctl(st, OPUS_GET_LAST_PACKET_DURATION(samples));
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}
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*/
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import "C"
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var errDecUninitialized = fmt.Errorf("opus decoder uninitialized")
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type Decoder struct {
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p *C.struct_OpusDecoder
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// Same purpose as encoder struct
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mem []byte
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sample_rate int
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channels int
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}
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// NewDecoder allocates a new Opus decoder and initializes it with the
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// appropriate parameters. All related memory is managed by the Go GC.
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func NewDecoder(sample_rate int, channels int) (*Decoder, error) {
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var dec Decoder
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err := dec.Init(sample_rate, channels)
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if err != nil {
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return nil, err
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}
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return &dec, nil
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}
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func (dec *Decoder) Init(sample_rate int, channels int) error {
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if dec.p != nil {
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return fmt.Errorf("opus decoder already initialized")
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}
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if channels != 1 && channels != 2 {
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return fmt.Errorf("Number of channels must be 1 or 2: %d", channels)
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}
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size := C.opus_decoder_get_size(C.int(channels))
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dec.sample_rate = sample_rate
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dec.channels = channels
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dec.mem = make([]byte, size)
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dec.p = (*C.OpusDecoder)(unsafe.Pointer(&dec.mem[0]))
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errno := C.opus_decoder_init(
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dec.p,
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C.opus_int32(sample_rate),
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C.int(channels))
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if errno != 0 {
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return Error(errno)
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}
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return nil
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}
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// Decode encoded Opus data into the supplied buffer. On success, returns the
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// number of samples correctly written to the target buffer.
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func (dec *Decoder) Decode(data []byte, pcm []int16) (int, error) {
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if dec.p == nil {
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return 0, errDecUninitialized
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}
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if len(data) == 0 {
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return 0, fmt.Errorf("opus: no data supplied")
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}
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if len(pcm) == 0 {
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return 0, fmt.Errorf("opus: target buffer empty")
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}
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if cap(pcm)%dec.channels != 0 {
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return 0, fmt.Errorf("opus: target buffer capacity must be multiple of channels")
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}
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n := int(C.opus_decode(
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dec.p,
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(*C.uchar)(&data[0]),
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C.opus_int32(len(data)),
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(*C.opus_int16)(&pcm[0]),
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C.int(cap(pcm)/dec.channels),
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0))
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if n < 0 {
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return 0, Error(n)
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}
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return n, nil
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}
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// DecodeFloat32 encoded Opus data into the supplied buffer. On success, returns the
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// number of samples correctly written to the target buffer.
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func (dec *Decoder) DecodeFloat32(data []byte, pcm []float32) (int, error) {
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if dec.p == nil {
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return 0, errDecUninitialized
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}
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if len(data) == 0 {
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return 0, fmt.Errorf("opus: no data supplied")
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}
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if len(pcm) == 0 {
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return 0, fmt.Errorf("opus: target buffer empty")
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}
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if cap(pcm)%dec.channels != 0 {
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return 0, fmt.Errorf("opus: target buffer capacity must be multiple of channels")
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}
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n := int(C.opus_decode_float(
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dec.p,
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(*C.uchar)(&data[0]),
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C.opus_int32(len(data)),
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(*C.float)(&pcm[0]),
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C.int(cap(pcm)/dec.channels),
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0))
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if n < 0 {
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return 0, Error(n)
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}
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return n, nil
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}
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// DecodeFEC encoded Opus data into the supplied buffer with forward error
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// correction.
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//
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// It is to be used on the packet directly following the lost one. The supplied
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// buffer needs to be exactly the duration of audio that is missing
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//
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// When a packet is considered "lost", DecodeFEC can be called on the next
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// packet in order to try and recover some of the lost data. The PCM needs to be
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// exactly the duration of audio that is missing. `LastPacketDuration()` can be
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// used on the decoder to get the length of the last packet. Note also that in
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// order to use this feature the encoder needs to be configured with
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// SetInBandFEC(true) and SetPacketLossPerc(x) options.
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//
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// Note that DecodeFEC automatically falls back to PLC when no FEC data is
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// available in the provided packet.
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func (dec *Decoder) DecodeFEC(data []byte, pcm []int16) error {
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if dec.p == nil {
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return errDecUninitialized
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}
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if len(data) == 0 {
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return fmt.Errorf("opus: no data supplied")
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}
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if len(pcm) == 0 {
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return fmt.Errorf("opus: target buffer empty")
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}
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if cap(pcm)%dec.channels != 0 {
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return fmt.Errorf("opus: target buffer capacity must be multiple of channels")
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}
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n := int(C.opus_decode(
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dec.p,
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(*C.uchar)(&data[0]),
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C.opus_int32(len(data)),
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(*C.opus_int16)(&pcm[0]),
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C.int(cap(pcm)/dec.channels),
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1))
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if n < 0 {
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return Error(n)
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}
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return nil
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}
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// DecodeFECFloat32 encoded Opus data into the supplied buffer with forward error
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// correction. It is to be used on the packet directly following the lost one.
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// The supplied buffer needs to be exactly the duration of audio that is missing
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func (dec *Decoder) DecodeFECFloat32(data []byte, pcm []float32) error {
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if dec.p == nil {
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return errDecUninitialized
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}
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if len(data) == 0 {
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return fmt.Errorf("opus: no data supplied")
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}
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if len(pcm) == 0 {
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return fmt.Errorf("opus: target buffer empty")
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}
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if cap(pcm)%dec.channels != 0 {
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return fmt.Errorf("opus: target buffer capacity must be multiple of channels")
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}
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n := int(C.opus_decode_float(
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dec.p,
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(*C.uchar)(&data[0]),
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C.opus_int32(len(data)),
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(*C.float)(&pcm[0]),
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C.int(cap(pcm)/dec.channels),
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1))
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if n < 0 {
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return Error(n)
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}
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return nil
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}
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// DecodePLC recovers a lost packet using Opus Packet Loss Concealment feature.
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//
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// The supplied buffer needs to be exactly the duration of audio that is missing.
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// When a packet is considered "lost", `DecodePLC` and `DecodePLCFloat32` methods
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// can be called in order to obtain something better sounding than just silence.
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// The PCM needs to be exactly the duration of audio that is missing.
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// `LastPacketDuration()` can be used on the decoder to get the length of the
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// last packet.
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//
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// This option does not require any additional encoder options. Unlike FEC,
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// PLC does not introduce additional latency. It is calculated from the previous
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// packet, not from the next one.
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func (dec *Decoder) DecodePLC(pcm []int16) error {
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if dec.p == nil {
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return errDecUninitialized
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}
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if len(pcm) == 0 {
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return fmt.Errorf("opus: target buffer empty")
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}
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if cap(pcm)%dec.channels != 0 {
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return fmt.Errorf("opus: output buffer capacity must be multiple of channels")
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}
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n := int(C.opus_decode(
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dec.p,
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nil,
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0,
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(*C.opus_int16)(&pcm[0]),
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C.int(cap(pcm)/dec.channels),
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0))
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if n < 0 {
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return Error(n)
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}
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return nil
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}
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// DecodePLCFloat32 recovers a lost packet using Opus Packet Loss Concealment feature.
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// The supplied buffer needs to be exactly the duration of audio that is missing.
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func (dec *Decoder) DecodePLCFloat32(pcm []float32) error {
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if dec.p == nil {
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return errDecUninitialized
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}
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if len(pcm) == 0 {
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return fmt.Errorf("opus: target buffer empty")
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}
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if cap(pcm)%dec.channels != 0 {
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return fmt.Errorf("opus: output buffer capacity must be multiple of channels")
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}
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n := int(C.opus_decode_float(
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dec.p,
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nil,
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0,
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(*C.float)(&pcm[0]),
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C.int(cap(pcm)/dec.channels),
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0))
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if n < 0 {
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return Error(n)
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}
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return nil
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}
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// LastPacketDuration gets the duration (in samples)
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// of the last packet successfully decoded or concealed.
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func (dec *Decoder) LastPacketDuration() (int, error) {
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var samples C.opus_int32
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res := C.bridge_decoder_get_last_packet_duration(dec.p, &samples)
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if res != C.OPUS_OK {
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return 0, Error(res)
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}
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return int(samples), nil
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}
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