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An audio player in golang.
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package main | |
import ( | |
"bytes" | |
"code.google.com/p/portaudio-go/portaudio" | |
"encoding/binary" | |
"fmt" | |
"io" | |
"log" | |
"os" | |
"os/exec" | |
) | |
func main() { | |
if len(os.Args) <= 1 { | |
fmt.Println("Usage:\n \t./ffmpeg audio_file") | |
os.Exit(0) | |
} | |
inputfile := os.Args[1] | |
chk := func(err error) { | |
if err != nil { | |
panic(err) | |
} | |
} | |
framePerBuffer := 2048 | |
ff := newFfmpeg(inputfile) | |
defer ff.Close() | |
stream, err := portaudio.OpenDefaultStream(0, 2, 44100, framePerBuffer, ff) | |
chk(err) | |
defer stream.Close() | |
chk(stream.Start()) | |
if err := ff.cmd.Wait(); err != nil { | |
log.Fatal(err) | |
} | |
chk(stream.Stop()) | |
} | |
type ffmpeg struct { | |
in io.ReadCloser | |
cmd *exec.Cmd | |
} | |
func newFfmpeg(filename string) *ffmpeg { | |
cmd := exec.Command("ffmpeg", "-i", filename, "-f", "s16le", "-") | |
stdout, err := cmd.StdoutPipe() | |
if err != nil { | |
log.Fatal(err) | |
} | |
if err := cmd.Start(); err != nil { | |
log.Fatal(err) | |
} | |
return &ffmpeg{stdout, cmd} | |
} | |
func (f *ffmpeg) Close() error { | |
return f.in.Close() | |
} | |
func (f *ffmpeg) ProcessAudio(_, out [][]int16) { | |
// int16 takes 2 bytes | |
bufferSize := len(out[0]) * 4 | |
var pack = make([]byte, bufferSize) | |
if _, err := f.in.Read(pack); err != nil { | |
log.Fatal(err) | |
} | |
n := make([]int16, len(out[0])*2) | |
for i := range n { | |
var x int16 | |
buf := bytes.NewBuffer(pack[2*i : 2*(i+1)]) | |
binary.Read(buf, binary.LittleEndian, &x) | |
n[i] = x | |
} | |
for i := range out[0] { | |
out[0][i] = n[2*i] | |
out[1][i] = n[2*i+1] | |
} | |
} |
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