This is a list of supported sound formats.
| Format | Usual file extension |
|---|---|
| RIFF WAVE | .wav |
| Native FLAC | .flac |
Please note that due to its 3D positional nature, openBVE will convert multi-channel audio to mono upon loading, so there is no point in providing multi-channel audio in the first place. For multi-channel audio, openBVE discards silent channels and tries to detect constructive or destructive interference in the mixed version of the remaining channels. If interference is detected, the first non-silent channel in the file is used, otherwise the mixed channel.
■ RIFF WAVE format
WAVE files are supported, which technically are RIFF (or RIFX) container files with the WAVE format type. WAVE itself allows different formats, of which only a subset are supported. These are:
| Format | Sample rate | Bitrate | Channels |
|---|---|---|---|
| PCM | any | any | any |
| Microsoft ADPCM | any | 4 bits | any |
Sample rate refers to the number of samples per second per channel. Bitrate refers to the umber of bits per sample per channel.
■ Native FLAC format
All native FLAC files are supported with the following (in practice rarely occuring) exceptions:
- Changing the sample rate in the middle of the file is not supported.
- Negative predictor shifts are not supported.
- MD5 checks are skipped for bit rates other than 8, 16 or 24.
Further information about these formats from a programmer’s point of view can be found on these external sites:
General information about RIFF, WAVE and PCM:
➟ http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Docs/riffmci.pdf
Information about Microsoft ADPCM:
➟ http://icculus.org/SDL_sound/downloads/external_documentation/wavecomp.htm
Official documentation on FLAC:
➟ http://flac.sourceforge.net/documentation.html
Additional documentation on FLAC:
➟ http://home.comcast.net/~b.langenb/audioformats_letter.pdf