Documentation
¶
Overview ¶
Package aiff is a AIFF/AIFC decoder and encoder. It extracts the basic information of the file and provide decoded frames for AIFF files.
This package also allows for quick access to the AIFF LPCM raw audio data:
in, err := os.Open("audiofile.aiff")
if err != nil {
log.Fatal("couldn't open audiofile.aiff %v", err)
}
d := NewDecoder(in)
frames, err := d.Frames()
in.Close()
A frame is a slice where each entry is a channel and each value is the sample value. For instance, a frame in a stereo file will have 2 entries (left and right) and each entry will have the value of the sample.
Note that this approach isn't memory efficient at all. In most cases you want to access the decoder's Clip. You can read the clip's frames in a buffer that you decode in small chunks.
Finally, the encoder allows the encoding of LPCM audio data into a valid AIFF file. Look at the encoder_test.go file for a more complete example.
Currently only AIFF is properly supported, AIFC files will more than likely not be properly processed.
Index ¶
- Variables
- type Chunk
- 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() (*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 ¶
var ( COMMID = [4]byte{'C', 'O', 'M', 'M'} SSNDID = [4]byte{'S', 'S', 'N', 'D'} // ErrFmtNotSupported is a generic error reporting an unknown format. ErrFmtNotSupported = errors.New("format not supported") // ErrUnexpectedData is a generic error reporting that the parser encountered unexpected data. ErrUnexpectedData = errors.New("unexpected data content") )
Functions ¶
This section is empty.
Types ¶
type Chunk ¶
Chunk is a struct representing a data chunk the reader is shared with the container but convenience methods are provided. The reader always starts at the beggining of the data. SSND chunk is the sound chunk Chunk specs: http://www.onicos.com/staff/iz/formats/aiff.html AFAn seems to be an OS X specific chunk, meaning & format TBD
func (*Chunk) IsFullyRead ¶
IsFullyRead checks if we're finished reading the chunk
type Decoder ¶
type Decoder struct {
// ID is always 'FORM'. This indicates that this is a FORM chunk
ID [4]byte
// Size contains the size of data portion of the 'FORM' chunk.
// Note that the data portion has been
// broken into two parts, formType and chunks
Size uint32
// Form describes what's in the 'FORM' chunk. For Audio IFF files,
// formType (aka Format) is always 'AIFF'.
// This indicates that the chunks within the FORM pertain to sampled sound.
Form [4]byte
NumChans uint16
NumSampleFrames uint32
BitDepth uint16
SampleRate int
//
PCMSize uint32
PCMChunk *Chunk
// AIFC data
Encoding [4]byte
EncodingName string
Debug bool
// contains filtered or unexported fields
}
Decoder is the wrapper structure for the AIFF container
func NewDecoder ¶
func NewDecoder(r io.ReadSeeker) *Decoder
NewDecoder creates a new reader reading the given reader and pushing audio data to the given channel. It is the caller's responsibility to call Close on the reader when done.
func (*Decoder) Duration ¶
Duration returns the time duration for the current AIFF container
Example ¶
package main
import (
"fmt"
"os"
"path/filepath"
"github.com/mattetti/audio/aiff"
)
func main() {
path, _ := filepath.Abs("fixtures/kick.aif")
f, err := os.Open(path)
if err != nil {
panic(err)
}
defer f.Close()
c := aiff.NewDecoder(f)
d, _ := c.Duration()
fmt.Printf("kick.aif has a duration of %f seconds\n", d.Seconds())
}
Output: kick.aif has a duration of 0.203356 seconds
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/aiff"
)
func main() {
f, err := os.Open("fixtures/kick.aif")
if err != nil {
log.Fatal(err)
}
defer f.Close()
fmt.Printf("is this file valid: %t", aiff.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
WrittenBytes int
// contains filtered or unexported fields
}
Encoder encodes LPCM data into an aiff content.
func NewEncoder ¶
func NewEncoder(w io.WriteSeeker, sampleRate, bitDepth, numChans int) *Encoder
NewEncoder creates a new encoder to create a new aiff file. Don't forget to add Frames to the encoder before writing.
Source Files