WAV
Waveform Audio File Format is an audio format with a .wav file extension, used by all of Valve's engines. It is required for lipsynced dialogue and looped sounds without a custom audio backend.
GoldSrc supports uncompressed 8-bit or 16-bit PCM, although lip-synched audio must be 8-bit. It supports sample rates of 11025 Hz or 22050 Hz; other sample rates can sometimes be used, but they will be resampled to 22050 Hz before playback.
Source supports uncompressed 8-bit and 16-bit PCM as well as compressed 4-bit Microsoft ADPCM. It supports sample rates at 11025 Hz, 22050 Hz, and 44100 Hz; files at other sample rates, such as 32000 Hz, will not play.
Bit rates
WAV files have a consistent bitrate depending upon their sample rate, bit depth, and channel count. The following is a table with the bitrates of mono WAV files; double the values below for stereo WAV files.
| Sample Rate | 16-bit PCM | 8-bit PCM | 4-bit ADPCM | Quality |
|---|---|---|---|---|
| 11025 Hz | 176.4 kbps | 88.2 kbps | 44.1 kbps | Used by most  sound effects
|
| 22050 Hz | 352.8 kbps | 176.4 kbps | 88.2 kbps | Max sample rate of sound effects
|
| 44100 Hz | 705.6 kbps | 352.8 kbps | 176.4 kbps | CD quality |