Audio Terminology Help

[cosmotron]

I have been trying to learn more about digital audio and I have a question.

I know about sample rates and bit rate depth/resolution and how they work together (the best analogy that I found describing them and how they relate to each other said that "imagine that you are looking at your backyard, a digital version would be like you are looking at it though a screen. If you had a sample rate of 44.1 kHz, then you would be looking at your backyard through a screen with 44100 holes in it. If you also had a bit depth of 16 bit, then each of the 44100 holes in the screen would have 65535 colors that could be represented.")

Now, I don't understand how bit rate comes into play (not bit rate depth/resolution). Like, if I have a 44.1kHz, 16bit, 320kbps song, how would the 320kbps fall into the backyard screen example?

Thanks for any help!

 

[jsmithepa]

To be completely accurate, you should say COMPRESSION BITRATE. Because that's what it is.

People concerned about bitrate are asking, OK, I know I am using a lossy compression (MP3, AAC) to represent the original WAV, so how many bits/s do I use for the compression? that is good enuff so I can't tell the difference/or not enuff difference to bother me, between the compressed MP3 versus original WAV?

More bits = more accurate representation of original WAV.

Sorry, I don't have a backyard analogy for you.

 

[DanT]

a 44100 sample/sec X 16 Bits x 2(stereo) = 1 411 200 bits/sec =1411,2 Kbits/sec

That the size of a raw PCM.

Now when you compress it with mp3 you apply a mathematical formula and reduce the size to 320 Kbits /sec Since the compression is lossy you lose some of the original information in this conversion.

I'm not very familiar with compression methodology so that a very gross explanation.

If you want an image analogy it's like a jpeg compression. If you use BMP it's the raw image so every pixel is describe pixel by pixel. Now a jpeg by some mean discard some information and approximate others so you can store the image in a much smaller size. In jpeg when you save you can tell it how much compression to apply and how much information is discard.

 

[cosmotron]

Ah, I see. Thanks a lot!