Re: Pb with es1370 and smp

Michael Mess (michael@kawo2.rwth-aachen.de)
Wed, 27 Oct 1999 16:54:52 +0200

Erwan MAS wrote:
>
> Hello ,
>
> Do you have found a solution about your problem
> with playing a wave file ?
> ( you get crackling noise ) .
>
> I have the same problem with playing MP3 .
>
I think that this is a timing problem with the DMA-timer.
It sounds like that the driver plays a block of a specified length and
then plays the next block of that length, but the problem is that
between these blocks there is a delay so that the value of the D/A
converter does not change for that delay. This gives something like a
hole in the signal.

I have then posted some program code which sets the fragment size to a
bigger value, so that there are not so many holes per second, so
reducing the distortion of the signal, but this does not solve the
problem completely.

As I am very busy at this time, I was not able to look deeper into the
es1370 code for the reason now, but I am still interested in that issue.

So I would like it, if the developers of the driver or any other people
send me some documentation of the es1370 chip. Maybe this could help me
finding the reason for that crackling noise.

This crackling noise does not occur on /dev/dsp1, so it might help, if I
know more about the differences between the devices behind /dev/dsp and
/dev/dsp1

Greetings, Michael

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