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Strange artifacts in mp3

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inot:
i've got old version of rockbox (version: r13302-070501). And i'v played mp3 without any problems, i've tryed to install new version (r14444), after this update i heard strange noise. I've tryed to format my ipod nano, and reistall (not upgrade) my rockbox, but artifacts didn't disappeared. i've install my old version of rockbox, and artifacts have gone.

artifacts = distortion

how can i solve this problem?

maraz:
I have the same problem on hot days. Cooling my iPod nano down helps with the problem, so it's obvious the problem is actually overheating. This probably only applies to specific batches of devices (or even individual devices!) which are used in warmer climates or seasons. People in colder areas aren't necessarily seeing the bug even if the possibility of it exists in their iPods.

This makes sense, because builds made before 26th July (15:07
"Clean up PP502x CPU clock setup code and use the full 80MHz when boosted.") seem to work fine, ie. it has been this clock speed raise from 75MHz to 80MHz that has made some devices unrealiable.

During the +25-30°C weeks here in finland it was practically impossible to use my iPod due to the glitches and skipping (and eventually the data aborts etc).

These threads are probably related to this:
http://forums.rockbox.org/index.php?topic=12336.0
http://forums.rockbox.org/index.php?topic=11817.0

Edit: forgot to mention this:

On hot days, when the device is overheating (it really feels hot!), even Windows sees garbled data on the device (when plugged in through USB). Filenames and directory names are corrupted, et cetera. Overheating -> I/O errors -> faulty reads from memories -> skipping MP3 playback (now that I mentioned it, it sounds 100x times worse than all those mp3's downloaded by modem back in the day) and corrupted MFT entries. Also, the corruption isn't non-volatile, so it isn't flash-based, but rather happens at the I/O processor.

Edit2: http://www.rockbox.org/tracker/task/7510?histring=7510 - here's the link to the tracker for what is probably this bug.

Llorean:
This is most likely coincidence, we've just had someone take a hairdryer to their working Nano and not show symptoms despite it being quite hot to the touch.

maraz:
Still, I'm a bit curious - my nano works perfectly well on below-20°C days, but over 20°C starts to show symptoms. The degree of symptoms varies significantly with the ambient temperature.

We need a larger sample of devices to rule out this possibility.

Edit: There are a couple of cases in the ticket comments that could be related to heat problems, such as these:

http://www.rockbox.org/tracker/task/7510#comment17288
http://www.rockbox.org/tracker/task/7510#comment17032

Llorean:
No, a single device rules this out as being a cause. If this were a cause it would work globally. More devices would simply show that cooler temperatures mitigate the problem, or that the heat increases its likelihood, but it's been shown that Nanos exist that do not show these symptoms under heat, so heat alone is not the cause.

As well, I live in Texas. It's bloody hot. Mine's never showed the problem. I took it to Puerto Rico. Where it's quite hot as well. No problem. Heat may make it more likely, or your personal one may have some form of damage drawn out by the heat that causes similar symptoms, but heat alone is not the cause of this problem.

And as to your quoting comment17288 as an example, it actually supports my point: Vorbis is generally less load on the iPods than MP3 right now, due to differing states of optimization. As well, FLAC uses vastly less, and seems to trigger it often for some people.

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