Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

In a MP3 audio file, I know theres a bitrate of audio which tells the number of bits in seconds are being used by the player, in other words a measure of quality of audio.

But I'm confused with the terms sample rate and sample size. Are they independent of the bitrate or quality of sound? or Can it be explained in some understandable terms?

share|improve this question
    
Have you seen this yet? –  techie007 Feb 10 '12 at 14:50
add comment

2 Answers

up vote 4 down vote accepted

Here is a great article on all three terms you're asking about. To summarize, here are the three definitions:

  1. bitrate: simply amount of data per second, this can vary within a file (variable bit rate) or have a static value
  2. sample rate: a frequency of how many times audio is measured per second, usually measured in kilohertz (kHz); a usual number you might see is 44.1kHz. This is tied directly to bit depth or the number of bits measured in each cycle

So at this point, we have to do some math and see that bit rate is bits per second (usually measured in Mbits/seconds), so bit rate = sample rate x bit depth. As far as I know, your sample size would simply be one of these one-second chunks of data.

Doing the pure math will reveal that these files would be very large, however there are a number of compression algorithms employed to keep the files lower without losing significant quality.

share|improve this answer
    
Note that for uncompressed audio, file size is indeed "sample_rate * bit_depth * no_of_channels * audio_size_in_s". Hence an hour of CD quality audio has 44,100*16*2*3600 =5,080,320,000 bit , or about 606 MiB. –  sleske Feb 13 '12 at 8:12
add comment

Sample Size or Bit Depth is a measure of how many bits a sample contains which is directly a measure of quality. But this applies only to PCM Sampling, For lossy formats like mp3, Sample size doesn't really define the quality.

Please visit Audio Bit Depth to learn more.

share|improve this answer
    
Even with lossy formats, sample size is still an important quality factor. It's just that it is not the only factor, because the fidelity of the compression used is also important. –  sleske Feb 13 '12 at 8:07
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.