Selecting Compression Parameters

About the sound quality / compression rate compromise

High quality of the compressed sound and high degree of compactness of the WMA audio file, determined by the selected bitrate (a number of kilobytes of data needed to represent one second of the encoded audio), are contradictory requirements which should be compromised according to ones needs.

First of all - how good is good enough? According to the results of listening tests, the sound encoded with the 64 kbits/s (kilobits per second) bitrate retains high quality referred to as a CD-quality. This means that if you compare the original music played from an audio CD with it’s WMA-encoded version you will hardly hear any difference. Of course, if you have more demanding ears you can choose higher bitrates: up to 160 kbits/s.

When storing CD-quality audio (44kHz, 16 bit, stereo) in an uncompressed WAVE format, the bitrate is approximately 1.4 Mbits/s (megabits per second). This means that using the 64 kbits/s WMA encoding you can compress your wave audio files 22 times. Using the lower quality encoding you can enforce even higher compression rates.The highest compression rates - up to 280 for the 5 kbits/s bitrate - are recommended for speech encoding only.

Presetting the WMA encoder

To preset the WMA encoder:

1. Select one of three quality levels

2. If you need a better control over the compression rate select the preferred bitrate (note: each quality level has it’s own bitrate range). Remember that higher bitrates correspond to higher sound quality but result in larger files.