Documentation
¶
Overview ¶
Package wav is a package allowing developers to decode and encode audio PCM data using the Waveform Audio File Format https://en.wikipedia.org/wiki/WAV
Index ¶
- type Decoder
- func (d *Decoder) Duration() (time.Duration, error)
- func (d *Decoder) EOF() bool
- func (d *Decoder) Err() error
- func (d *Decoder) Format() *audio.Format
- func (d *Decoder) FullPCMBuffer() (*audio.PCMBuffer, error)
- func (d *Decoder) FwdToPCM() error
- func (d *Decoder) IsValidFile() bool
- func (d *Decoder) NextChunk() (*riff.Chunk, error)
- func (d *Decoder) PCMBuffer(buf *audio.PCMBuffer) error
- func (d *Decoder) PCMLen() int64
- func (d *Decoder) ReadInfo()
- func (d *Decoder) Reset()
- func (d *Decoder) SampleBitDepth() int32
- func (d *Decoder) String() string
- func (d *Decoder) WasPCMAccessed() bool
- type Encoder
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Decoder ¶
type Decoder struct {
NumChans uint16
BitDepth uint16
SampleRate uint32
AvgBytesPerSec uint32
WavAudioFormat uint16
PCMSize int
// pcmChunk is available so we can use the LimitReader
PCMChunk *riff.Chunk
// contains filtered or unexported fields
}
Decoder handles the decoding of wav files.
func NewDecoder ¶
func NewDecoder(r io.ReadSeeker) *Decoder
NewDecoder creates a decoder for the passed wav reader. Note that the reader doesn't get rewinded as the container is processed.
func (*Decoder) Duration ¶
Duration returns the time duration for the current audio container
Example ¶
package main
import (
"fmt"
"log"
"os"
"github.com/mattetti/audio/wav"
)
func main() {
f, err := os.Open("fixtures/kick.wav")
if err != nil {
log.Fatal(err)
}
defer f.Close()
dur, err := wav.NewDecoder(f).Duration()
if err != nil {
log.Fatal(err)
}
fmt.Printf("%s duration: %s\n", f.Name(), dur)
}
Output: fixtures/kick.wav duration: 204.172335ms
func (*Decoder) FullPCMBuffer ¶
FullPCMBuffer is an inneficient way to access all the PCM data contained in the audio container. The entire PCM data is held in memory. Consider using Buffer() instead.
func (*Decoder) FwdToPCM ¶
FwdToPCM forwards the underlying reader until the start of the PCM chunk. If the PCM chunk was already read, no data will be found (you need to rewind).
func (*Decoder) IsValidFile ¶
IsValidFile verifies that the file is valid/readable.
Example ¶
package main
import (
"fmt"
"log"
"os"
"github.com/mattetti/audio/wav"
)
func main() {
f, err := os.Open("fixtures/kick.wav")
if err != nil {
log.Fatal(err)
}
defer f.Close()
fmt.Printf("is this file valid: %t", wav.NewDecoder(f).IsValidFile())
}
Output: is this file valid: true
func (*Decoder) ReadInfo ¶
func (d *Decoder) ReadInfo()
ReadInfo reads the underlying reader until the comm header is parsed. This method is safe to call multiple times.
func (*Decoder) Reset ¶
func (d *Decoder) Reset()
Reset resets the decoder (and rewind the underlying reader)
func (*Decoder) SampleBitDepth ¶
SampleBitDepth returns the bit depth encoding of each sample.
func (*Decoder) WasPCMAccessed ¶
WasPCMAccessed returns positively if the PCM data was previously accessed.
type Encoder ¶
type Encoder struct {
SampleRate int
BitDepth int
NumChans int
// A number indicating the WAVE format category of the file. The content of the
// <format-specific-fields> portion of the ‘fmt’ chunk, and the interpretation of
// the waveform data, depend on this value.
// PCM = 1 (i.e. Linear quantization) Values other than 1 indicate some form of compression.
WavAudioFormat int
WrittenBytes int
// contains filtered or unexported fields
}
Encoder encodes LPCM data into a wav containter.
func NewEncoder ¶
func NewEncoder(w io.WriteSeeker, sampleRate, bitDepth, numChans, audioFormat int) *Encoder
NewEncoder creates a new encoder to create a new wav file. Don't forget to add Frames to the encoder before writing.
func (*Encoder) Close ¶
Close flushes the content to disk, make sure the headers are up to date Note that the underlying writter is NOT being closed.
func (*Encoder) Write ¶
Write encodes and writes the passed buffer to the underlying writer. Don't forger to Close() the encoder or the file won't be valid.
Example ¶
package main
import (
"fmt"
"os"
"github.com/mattetti/audio/wav"
)
func main() {
f, err := os.Open("fixtures/kick.wav")
if err != nil {
panic(fmt.Sprintf("couldn't open audio file - %v", err))
}
// Decode the original audio file
// and collect audio content and information.
d := wav.NewDecoder(f)
buf, err := d.FullPCMBuffer()
if err != nil {
panic(err)
}
f.Close()
fmt.Println("Old file ->", d)
// Destination file
out, err := os.Create("testOutput/kick.wav")
if err != nil {
panic(fmt.Sprintf("couldn't create output file - %v", err))
}
// setup the encoder and write all the frames
e := wav.NewEncoder(out,
buf.Format.SampleRate,
buf.Format.BitDepth,
buf.Format.NumChannels,
int(d.WavAudioFormat))
if err := e.Write(buf); err != nil {
panic(err)
}
// close the encoder to make sure the headers are properly
// set and the data is flushed.
if err := e.Close(); err != nil {
panic(err)
}
out.Close()
// reopen to confirm things worked well
out, err = os.Open("testOutput/kick.wav")
if err != nil {
panic(err)
}
d2 := wav.NewDecoder(out)
d2.ReadInfo()
fmt.Println("New file ->", d2)
out.Close()
os.Remove(out.Name())
}
Output: Old file -> Format: WAVE - 1 channels @ 22050 / 16 bits - Duration: 0.204172 seconds New file -> Format: WAVE - 1 channels @ 22050 / 16 bits - Duration: 0.204172 seconds
Source Files