This paper proposes a novel method for vector coding

which approximately represents a vector with its orthogonal projection on a straight line.It encodes every vector with 3 codes

where two are used to represent two reference points to determine a straight line

and the third one is used to describe the location of the projection point.Since a N-sized vector quantization (VQ) codebook can determine N(N-1)/2 different straight lines

the new method can encode vectors with very high coding accuracy based on a rather small codebook.Theoretical analysis and experimental results suggest that its coding accuracy based on a N-sized code-book of size N N

2

is comparable with that of VQ coding based on a N

2

-sized codebook

and much better than multi-stage VQ based on two codebooks of size N

while its computational complexity is much lower than the latter ones under equivalent accuracy obtained.The method would be a powerful tool for vector coding with high accuracy requirement.