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Topic: Learn about AC'97, etc? (Read 2880 times) previous topic - next topic
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Learn about AC'97, etc?

I remember spotting this forum like a year ago and kept it in the back of my mind.  I'm in mechanical engineering and do audio recording as a hobby.  I'm interested in learning about hardware codecs, AD/DA.  There are a lot of myths/legends circulating the internet about AD and DA conversion, and being that I do recording in a home studio, it's always been of interest.  I have basic knowledge, but I got an Omnia II cell phone recently and that's why I'm here now: the phone has an AK4671 codec.  From the store, the volume was too low and the quality is not so great.  I got the volume fixed, but in the process I found the data sheet for the chip.  There's tons of information there that I do not understand, and I was hoping someone here could point me in the right direction (what books?) for learning about these chips and how they're implemented in devices.  Also, there are lots of parameters that I can adjust thru registry on this Windows Mobile phone, and some of them go right over my head.  I can tell that the high frequencies are not nearly as crisp and clear as they *should* be, and I wouldn't be surprised if the entirety of the audio is distorted - it's just easier to single out the high freqs.  I was able to affect them somewhat by adjusting clock settings on the hardware codec, but it's all just guess and check.  I'd love to have a better understanding, and I don't know where to look.  Advice? 

Thnx,
GainBrains

Learn about AC'97, etc?

Reply #1 –
National Instruments (a manufacturer of high performance ADCs and DACs for engineering and scientific applications) has a great deal of information in their tutorials and tech documents.

Learn about AC'97, etc?

Reply #2 –
Hah, awesome.  I never would have thought about NI, and I use several of their products!  Thanks for the suggestion!

Learn about AC'97, etc?

Reply #3 –
There is a good FREE online book called The Scientist and Engineer's Guide to Digital Signal Processing[/u]. 

Quote
I can tell that the high frequencies are not nearly as crisp and clear as they *should* be, and I wouldn't be surprised if the entirety of the audio is distorted - it's just easier to single out the high freqs.
I think this is mostly the result of lossy compression...  I'm not sure if you can blame the phone, unless other phones on the same network have better sound.    (BTW - I don't think there is any mention of lossy compression in the above "introductory" DSP book.)