go-lame

Yet another simple wrapper of libmp3lame for golang. It focuses on converting raw PCM, and WAV files into mp3.

Examples

PCM to MP3

Assuming the sample rate of the PCM file is 44100, and the output's is the same.

func PcmToMp3(pcmFileName, mp3FileName string) {
	pcmFile, _ := os.OpenFile(pcmFileName, os.O_RDONLY, 0555)
	mp3File, _ := os.OpenFile(mp3FileName, os.O_CREATE | os.O_WRONLY | os.O_TRUNC, 0755)
	defer mp3File.Close()
	wr, err := lame.NewWriter(mp3File)
	if err != nil {
		panic("cannot create lame writer, err: " + err.Error())
	}
	io.Copy(wr, pcmFile)
	wr.Close()
}

PCM to MP3 (Customize params)

Assuming here goes some properties of the PCM file:

- SampleRate: 16000,
- Number of Channel: 1 (single),

and the output (.mp3) is expected to meet demands below:

- SampleRate: 8000
- Quality: 9 (lowest)
- Mode: Stereo (2 channels)

func PcmToMp3Customize(pcmFileName, mp3FileName string) {
	pcmFile, _ := os.OpenFile(pcmFileName, os.O_RDONLY, 0555)
	mp3File, _ := os.OpenFile(mp3FileName, os.O_CREATE | os.O_WRONLY | os.O_TRUNC, 0755)
	defer mp3File.Close()
	wr, err := lame.NewWriter(mp3File)
	if err != nil {
		panic("cannot create lame writer, err: " + err.Error())
	}
	wr.InSampleRate = 44100  // input sample rate
	wr.InNumChannels = 1     // number of channels: 1
	wr.OutMode = lame.MODE_STEREO // common, 2 channels
	wr.OutQuality = 9        // 0: highest; 9: lowest 
	wr.OutSampleRate = 8000  // output sample rate
	
	io.Copy(wr, pcmFile)
	wr.Close()
}

WAV to MP3

func WavToMp3(wavFileName, mp3FileName string) {
	// open files
	wavFile, _ := os.OpenFile(wavFileName, os.O_RDONLY, 0555)
	mp3File, _ := os.OpenFile(mp3FileName, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0755)
	defer mp3File.Close()

	// parsing wav info
	// NOTE: reader position moves even if it is not a wav file
	wavHdr, err := lame.ReadWavHeader(wavFile)
	if err != nil {
		panic("not a wav file, err=" + err.Error())
	}

	wr, _ := lame.NewWriter(mp3File)
	wr.EncodeOptions = wavHdr.ToEncodeOptions()
	io.Copy(wr, wavFile) // wavFile's pos has been changed!
	wr.Close()
}

Roadmap

• Wrapping functions from libmp3lame
• WavFile parsing support
• Shortcut to using wrapped functions
• Supporting parsing both little-endian and big-endian PCM files
• Thorough tests
• Supporting bit depth other than 16