[cma-l] Audio crackling

Mon Oct 31 13:26:52 GMT 2011

Great to get so much support from so many (already busy) people! CMA
rocks!!!

The powersupply is the most expensive part of the computer!! An Enermax
psu, cost me about 85 quid! (although two of these have already died on me,
so not so confident about them...!)
I'm going to wait until the next song ends, and try playing a CD, thus
bypassing a lot of the computer stuff, see what happens...

...yup the Serbian folk CD I just put on has no crackling, incl in the
stream!!

The plot thickens....  will keep looking at all the possibilities you have
suggested. (Alex 師傅  - I am in total awe about what you managed to get from
listening to 20s or so audio...!)

Peter

2011/10/31 Two Lochs Radio <tlr at gairloch.co.uk>

> **
> Okay, no that doesn't sound like a buffer problem at all.
>
> If the crackle continues during silent passages i would say it is a
> hardware problem, most probably a power supply filtering issue. (It could
> be, for example, a dried out electrolytic capacitor that cease to perform
> sufficient filtering as it gets a bit warmer.)
>
> If the crackling disappears or changes greatly during silent passages,
> which it sounds like it does, I would say it was more likely a software
> problem. It does change a little as the sound gets louder, but this could
> happen as power loading changes with the volume.
>
> It could also be a 'rectifying contact' - usually a dirty or tarnished
> one, or a cracked resistor among many posibilities.
>
> There is very distinct almost continuous series of spikes at 204Hz (4.88ms
> period) which ought to give a clue, but doesn't immediately ring any bells,
> so to speak.
>
>  If it is software, it might be something happening at high speed, for
> example if you are using the card to perform a sampling rate conversion (eg
> 44.1kHz to 48kHz), and it is failing to keep up with the pace, that could
> possibly produce crackle effects.
>
> I don't think your hard drive is implicated, but it is possible that the
> crackle is a manifestation some data issues where the data is passing at a
> high rate beween the drive and the system - maybe a problem with DMA
> interrupts/speed of access, but my gut feel is that is not the most likely
> cause - it does sound more like audio hardware/power problems to me (as i
> stab in the dark!).
>
> Alex
>
> ----- Original Message -----
> *From:* London Chinese Radio <admin at londonhuayu.co.uk>
> *To:* Two Lochs Radio <tlr at gairloch.co.uk> ; Tony Bailey<studio at ravensoundradio.co.uk>
> *Cc:* CMA-L <cma-l at commedia.org.uk>
> *Sent:* Monday, October 31, 2011 12:48 PM
> *Subject:* Re: [cma-l] Audio crackling
>
> Hi,
>
> Here is a sample of the audio. As you can see, it's pretty bad!
> It doesn't solve it by disconnecting and reconnecting the audio stream.
> But it does sound very software-y.
>
> The HD is an old IDE drive, but the motherboard, which has mostly SATA
> ports on it, had an IDE port, so I installed it. So it could be that...
> I'm not properly trained, only find out things by overcoming problems like
> this...!
>
> Anyway, I am attaching a small sample from the stream...
>
>
> Peter
>
>
>
>
> 2011/10/31 Two Lochs Radio <tlr at gairloch.co.uk>
>
>> **
>> Does the crackle stop for a while if you stop and restart the audio
>> stream? If so, that would suggest a small bite rate mismatch is not being
>> properly handled and is resulting in repeated buffer overflows, which
>> depending on how well the software handles dumping the excess data can
>> sound like a crackle or a 'glitch'.
>>
>> But the description 'crackle' can cover a multitude of effects. is it
>> possible for you to post a little audio sample of it somewhere we can
>> access (or email me a small pice directly if you want) in case the actual
>> sound triggers any other thoughts.
>>
>> Alex
>>
>>
>>   ----- Original Message -----
>> *From:* London Chinese Radio <admin at londonhuayu.co.uk>
>> *To:* CMA-L <cma-l at commedia.org.uk>
>> *Sent:* Monday, October 31, 2011 10:41 AM
>> *Subject:* [cma-l] Audio crackling
>>
>> Hi,
>>
>> I wonder if anyone has had problems with audio crackling?
>> I have recently changed to a different streaming PC, (because it was XP,
>> and I had a Marian marc8 midi sound card which has 8 ins and outs, but
>> doesn't support Win7), and it was fine for about a month, until it started
>> crackling. I put all the audio on a seperate HD, and because they are quite
>> close together, I also fitted a large fan next to them, which delivers
>> quite an icy blast across the disks.
>> It starts crackling after a few hours, and it ruins the stream. It is
>> solvable by rebooting. I originally thought it could be something
>> overheating, but since it is solved by rebooting, without the time for
>> anything to cool down, I don't think that is it.
>>
>> System info:
>>
>> Airmate out into Soundcard in (channels 1 & 2)
>> mAirlist (6 Channels) and computer audio (2 channels) via Soundcard outs
>> into Airmate channels
>> Asus P5K-VM motherboard with an Intel Core2 duo CPU. (it's a Red Sub
>> computer with a few extra things I've added)
>> The CPU cooler is a bog standard one but with a funnel that directs the
>> hot air out of a vent on the side.
>>
>> Anyway, if you have an idea, I'd really appreciate any advice.
>>
>>
>> Peter Vautier
>> London Chinese Radio
>> --
>> 野火烧不尽，春风吹又生
>>
>> ------------------------------
>>
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>
>
> --
> 野火烧不尽，春风吹又生
>
>

-- 
野火烧不尽，春风吹又生
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