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Test your soundcard for clipping, with this sample
post Feb 6 2008, 18:14
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QUOTE (maiki @ Feb 6 2008, 17:01) *
I have tested UDIAL.WAV encoded into 320 kbps MP3 [...]
distorted = I can hear cracking (clipping?) AT ANY VOLUME LEVEL
What is going on here?

This clipping is the result of encoding into MP3, nothing with your hardware.
Download LAME 3.97 and encode UDIAL.WAV as

"lame.exe -b 320 -k udial.wav udial.mp3"
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post Feb 7 2008, 06:31
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Just thinking about how many people might have accidentally left this in their library over the years and had it come on when listening to random music with the sound cranked up. ohmy.gif
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post Feb 7 2008, 08:21
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Hello all. New member and decided to respond to this thread with my first post. biggrin.gif

Anyway, I downloaded the original APE file in the first post and tested it on my system.

Here is my setup:

Windows XP SP2
Creative Soundblaster Live! PCI Value
DirectX 9.0c

All Windows XP Updates as of February 2008 except for DirectX (I don't have DX10 installed yet). I also have the latest drivers I could get for all my hardware.

Software Media Player: XMPlay (by Un4Seen Developments) with Monkey Audio Plugin (xm-ape.dll)

using Output Device: DirectSound - SB Live! Audio [D000] with 16-bit stereo.

Also, using a set of "average" on-the-ear headphones plugged into the SB Live! They are "average" because I spent just $25 on them. So I guess they are "mainstream consumer" headphones. They are rated at 16 Ohm impedance and frequency range 20 - 22000 Hz with a SNR of 98 dB.

I turned off all reverb/chorus/equalizer and any other DSP effects in XMPlay. I also set the main WIndows Mixer volume to 50% with Wave volume to 100%. Within XMPlay I set the volume slider to 10% and then moved it up slowly until I reached a light comfortable listening level which was achieved at 30%.

With the regular non-altered 44100 Hz output, I get the starting 3 "beeps" of touch tone dialing and then a really high pitched razzing noise, like a ray gun firing or alien spaceship, that overpowers the rest of the beeps.

However, if I tell XMPlay to resample to 48000 Hz, that razzing noise goes away and I get only the touch tones, which I presume is the 'correct' sound.

If this is correct, then XMPlay's resampling to 48000Hz for Creative cards works very well. Before this test, I have always had XMPlay resample all sounds to 48000 Hz before outputting to the sound device because I had already read about the subpar upsampling that many Creative cards do.

My motherboard also has a built-in C-Media Wave AC'97 sound device, but I rarely use that thing so I didn't test it.

This post has been edited by WonderSlug: Feb 7 2008, 08:25
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post May 8 2008, 17:09
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The old links to udial.flac don't work, so I'm rehosting the file (I converted this to flac from the .ape file, whose link still does work)


This post has been edited by krabapple: May 8 2008, 17:10
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post Jul 14 2009, 22:40
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audigy 2 zs, windows vista, foobar direct sound output, PPHS resampler. it sounds ok only if resampled at 32KHz OR if replaygain clipping prevention is applied and the volume is then lowered of about 20db

This post has been edited by v.43: Jul 14 2009, 23:29
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Arnold B. Kruege...
post Jul 15 2009, 12:07
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QUOTE (Jan S. @ May 26 2003, 14:57) *
For everybody fighting with occasional clipping (or perfectionists wanting to test everything) you should try the attached sample, udial.

  • play the sample in your favourite player (decoded or not, having disabled all DSPs and EQs that can interfere)
  • if the output sounds weird at any time you should:
    • lower the output vol. in your soundcard config (should be the speaker icon in your system tray).
    • For some soundcards 48kHz is better (audigy 2 etc.).
    • lower the vol. till the sample doesn't sound weird at any time.
The output will sound really weird if your settings clip.
Your output can occasional clip without you knowing/hearing it. But for us perfectionists this will theoretically give a better quality output.

ATTENTION: Play this sample at a low volume anytime, even if you hear nothing special! It can be very harmful to equipment and/or your ears.
It's strongly recommended to use some very cheap (PC) speakers if you want to test this,
otherwise you might really ruin your tweeters (it has happened several times already).

*pedantic hat on*

Well yes it works, but it begs the question what sort of a signal makes the best possible audible test for clipping.

IMO the best possible test is the one that gives a clear audible indication with the least possible clipping.

I've long thought that the best way to do this would be to mix two tones that are < 22 KHz but high enough to be *every* hard to hear when they are pure tones. When clipped, there would be numerous spurious products smack dab in the middle of the the range where the ear is most sensitive.

I was just playing with such a pair of tones that I quickly generated in CEP/Audition. I could easily hear a difference when just 2,000 of 400,00 samples were clipped. Intrestingly enough, no single spurious response was above - 90 dB FS, but there were a lot of them.

With Udial, I had to clip about six times the percentage of samples before I could detect clipping as easily. The problem with Udial was that the stimulus tones were in the same frequency range as the spurious responses, and clearly audible. So they tended to mask their own distortion The spurious responses were few in number, but only about 40 dB down.

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post Oct 15 2013, 22:19
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I found it useful for detecting (and then eliminating) low-quality play-back chain resampling.

However, there were a few things I didn't like about it, so I made a new version, uploaded here.
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post Oct 16 2013, 09:01
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Here is another clipping test for inter-sample peaks:

sine 0 15 11025 45 0.8918058 0.8918058
sine 0 15 15017 0 0.369398 0.369398

It can be compiled with the "testgen" utility from here. The sample rate should be 44100 Hz. Note that this is a very loud high frequency signal, and can be dangerous if not played at low volume. It has a peak level of about +2 dBFS when reconstructed, which is about the maximum I have found in music. Some sound cards can actually play this without significant clipping (for example, my Xonar D1), but most have a hard limit at 0 dBFS at full digital volume.

This post has been edited by stv014: Oct 16 2013, 09:01
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post Feb 21 2014, 19:39
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Hello, i thought of testing my lumia 520 smartphone with this sample.

1. Converted this flac as wav, to test if 520 is resampling to 48k, as WP8 not support flac.
2. Resampled this sample to 48k and 96k using sox foobar plugin. To test bad resampling to 44.1k.
please advice me if this is not the correct way to test bad resampling to 44.1k.

All the 3 samples are playing fine in my 520 at all volumes.

I tried these samples in Samsung note(think first version), i heard sirens for 48k version.
I read people say android has fixed sampling rate, so I tried neutron player since it advertises about resampling quality.
I selected audiophile resampling option, but still I can hear the siren.

My question, is WP8 really good in resampling? Is neutron players resampling not worth its claim? Or is android resampling the good signal from neutron with its bad algorithms?

Has anyone tried this on your lumia?
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post Feb 23 2014, 13:04
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Free flac app. Not very useful because files must be uploaded to skydrive first then download to the phones' internal memory, no SD card support. But for testing it suffices for your needs.

I have a Lumia 520 and could not find any resampling artifacts in playing 44.1k flacs by using RMAA, which means the performance is indistinguishable from 48k. Also, udial is not a suitable tool for testing resampler performance because it can clip easily and generate artifacts which are not related to bad resampling. The title of this thread says "Test your soundcard for clipping" therefore you should not use it to test resampling quality.

This post has been edited by bennetng: Feb 23 2014, 13:11
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