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@krzemienski
Forked from aperture147/ffmpeg.go
Created February 8, 2024 22:21
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fix make buffer
package main
import (
"bytes"
"io/ioutil"
"log"
"os"
"os/exec"
)
func check(err error) {
if err != nil {
log.Fatalln(err)
}
}
func main() {
file, err := os.Open("test.mp3") // open file
check(err)
defer file.Close()
buf, err := ioutil.ReadAll(file)
check(err)
cmd := exec.Command("ffmpeg", "-y", // Yes to all
//"-hide_banner", "-loglevel", "panic", // Hide all logs
"-i", "pipe:0", // take stdin as input
"-map_metadata", "-1", // strip out all (mostly) metadata
"-c:a", "libmp3lame", // use mp3 lame codec
"-vsync", "2", // suppress "Frame rate very high for a muxer not efficiently supporting it"
"-b:a", "128k", // Down sample audio birate to 128k
"-f", "mp3", // using mp3 muxer (IMPORTANT, output data to pipe require manual muxer selecting)
"pipe:1", // output to stdout
)
// resultBuffer := bytes.NewBuffer(make([]byte, 0)) // uncomment this line if you don't want to preallocate the buffer
resultBuffer := bytes.NewBuffer(make([]byte, 5*1024*1024)) // pre allocate 5MiB buffer
cmd.Stderr = os.Stderr // bind log stream to stderr
cmd.Stdout = resultBuffer // stdout result will be written here
stdin, err := cmd.StdinPipe() // Open stdin pipe
check(err)
err = cmd.Start() // Start a process on another goroutine
check(err)
_, err = stdin.Write(buf) // pump audio data to stdin pipe
check(err)
err = stdin.Close() // close the stdin, or ffmpeg will wait forever
check(err)
err = cmd.Wait() // wait until ffmpeg finish
check(err)
outputFile, err := os.Create("out.mp3") // create new file
check(err)
defer outputFile.Close()
_, err = outputFile.Write(resultBuffer.Bytes()) // write result buffer to file
check(err)
}
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