This is a modified version of AudioSprite by Tõnis Tiigi https://github.com/tonistiigi/audiosprite Additional changes by CloudKid Studio https://github.com/CloudKidStudio/audiosprite

What?

This is a ffmpeg wrapper that will take in multiple audio files and combines them into a single file. Silent gaps will be put between the parts so that every new part starts from full second and there is at least 1 second pause between every part. The final file will be exported in mp3, ogg, ac3, m4a and caf(IMA-ADPCM) to support as many devices as possible. This tool will also generate a JSON file that is compatible with HowlerJS.

Why?

iOS, Windows Phone and some Android phones have very limited HTML5 audio support. They only support playing single file at a time and loading in new files requires user interaction and has a big latency. To overcome this there is a technique to combine all audio into single file and only play/loop certain parts of that file.

###Installation

npm install -g pbsaudiosprite

Hints for Windows users

• You need to install Node.js
• Use Git Bash instead of Command Line or Powershell
• Download ffmpeg and include it in your path export PATH=$PATH:path/to/ffmpeg/bin
• IMA-ADPCM(the fastest iPhone format) will only be generated if you are using OSX.

###Usage

> pbsaudiosprite --help
info: Usage: pbsaudiosprite [options] file1.mp3 file2.mp3 *.wav
info: Options:
  --output, -o      Name for the output file.                                    [default: "output"]
  --export, -e      Limit exported file types. Comma separated extension list.   [default: ""]
  --log, -l         Log level (debug, info, notice, warning, error).             [default: "info"]
  --autoplay, -a    Autoplay sprite name                                         [default: null]
  --silence, -s     Add special "silence" track with specified duration.         [default: 0]
  --samplerate, -r  Sample rate.                                                 [default: 44100]
  --channels, -c    Number of channels (1=mono, 2=stereo).                       [default: 1]
  --rawparts, -p    Include raw slices(for Web Audio API) in specified formats.  [default: ""]
  --bitrate, -b     The bitrate quality for the exported audio.                  [default: 128]
  --help, -h        Show this help message.


> pbsaudiosprite --output mygameaudio bg_loop.wav *.mp3
info: File added OK file=bg_loop.wav
info: 1.25s silence gap added OK
info: File added OK file=click.mp3
info: 1.70s silence gap added OK
info: Exported caf OK file=mygameaudio.caf
info: Exported ac3 OK file=mygameaudio.ac3
info: Exported mp3 OK file=mygameaudio.mp3
info: Exported m4a OK file=mygameaudio.m4a
info: Exported ogg OK file=mygameaudio.ogg
info: Exported json OK file=mygameaudio.json
info: All done


> cat mygameaudio.json
{
  "urls": [
    "mygameaudio.caf",
    "mygameaudio.ac3",
    "mygameaudio.mp3",
    "mygameaudio.m4a",
    "mygameaudio.ogg"
  ],
  "sprite": {
    "bg_loop": [0, 3.75],
    "click": [5, 5.3]

    }
}

####Custom silent track

On some cases starting and pausing a file has bigger latency than just setting playhead position. You may get better results if your file is always playing. --silence <duration> option will generate extra track named silence that you can play instead of pausing the file.