VQF, otherwise known as Vector Quantization Format is an audio encoding technology that uses the unique Vector Quantization technology to encode.
The format was one of the "alternative" audio compression formats back in 1990s that was aimed to take over MP3 by providing better audio quality than MP3 with lower bitrate. However, this format failed like many others due to restrictive licensing and other limitations. These limitations were 2 channels at most, restrictive CBR and slow encoding.
When the format was still viable, Yamaha bought the VQF technology and created their own encoder, dubbed SoundVQ. After the format died however, Yamaha discounted the encoder and all support for it.
Nowadays the only serious alternatives to MP3 are probably Ogg Vorbis and Microsoft's WMA.