Coding block length trades side-information cost against noise masking.
Evidence
Forward adaptive quantizers: Look at a block of the input signal and then set a scale factor that makes maximum use of the quantizer. This type of adaptive quantizer is guaranteed to be free from overload and is more robust to errors. However, it needs some side information—the scale factor—to be sent to the receiving end, which clearly robs bits from the quantized signal samples. Therefore, there is an uncomfortable balance that must be struck between the amount of side information and the number of levels in the adaptive quantizer. In particular, if the block is made longer, less scale values have to be sent to the receiver. But if the block is too long, the quantization noise may become unmasked due to nonsimultaneous masking. So the block size is set typically within the range 8 to 25 ms to avoid this happening. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2662
Therefore there is an uncomfortable balance that must be struck between the amount of side information and the number of levels in the adaptive quantizer. In particular, if the block is made longer then less scale values have to be sent to the receiver. But if the block is too long then the quantization noise may become unmasked, due to nonsimultaneous masking. So the block size is set typically within the range 8–25 ms to avoid this happening. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2660
Categorization
- DEFINE: Explains what a forward adaptive quantizer is and how its design parameters interact.
- corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2662; David Howard, Jamie Angus, coustics and Psychoacoustics, 2660