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Topic: Famous udial sample not fixed by Resampler (SSRC) (Read 4090 times) previous topic - next topic
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Famous udial sample not fixed by Resampler (SSRC)

Lately I was playing with the udial sample. No matter how I configure fb2k, I get the ambulance-siren sound which means crappy resampling. When I resampled that sample with SOX to 48KHz wav, the siren effect disappeard - I got clean dial tones only. It would mean that Resampler (SSRC) doesn't resample in the best possible way. If it would resample 44KHz to 48KHz in the same way as SOX, I would get nearly perfect sound. Can anything be done about it?

Famous udial sample not fixed by Resampler (SSRC)

Reply #1 –
If you read the udial-related thread ("Test your soundcard for clipping" IIRC) you'll notice that for most people problems disappear when resampling to 48kHz with fb2k. Make sure that you have dithering (especially noiseshaped dither) and replaygain disabled and try again.
Dither -> The high-frequency sounds are full-scale, if you add quite loud high frequency noise (noiseshaped dither) you'll get clipping -> obvious audible distortion
Replaygain -> IIRC enabling replaygain at default settings causes positive amplification with this sample as the audible part is quite low volume. Result: clipping -> distortion.

Edit: Problem solved? This doesn't mean that replaygain and dither is bad, under normal circumstances you won't get clipping. If you listen to music with huge dynamic range with replaygain enabled, use some limiter DSP (and/or check "scale down ..." box in replaygain options) if you want to be sure that there's no clipping.

Still problems? Use diskwriter and upload the result, please.
Let's suppose that rain washes out a picnic. Who is feeling negative? The rain? Or YOU? What's causing the negative feeling? The rain or your reaction? - Anthony De Mello

Famous udial sample not fixed by Resampler (SSRC)

Reply #2 –
Clipping isn't the problem in my case, I get no clipping at all. The problem seems to be in resampling anti-aliasing which mirrors that high frequency sine wave to lower frequencies. I'm playing with it right now, I'll upload the fb2k & SOX results today...

...OK, here they are:
Upsampled by fb2k
Upsampled by sox

Hmm, wave coming from SOX seems to be much quieter than that coming from fb2k, perhaps thats why I can't hear the "siren"?


EDIT: I removed the links from this post.

Famous udial sample not fixed by Resampler (SSRC)

Reply #3 –
Both of your uploaded samples play without distortion (siren) here. CoolEdit doesn't show anything that isn't supposed to be there either in the decoded .wavs (besides SOX resampling seems to attenuate high frequencies; this is most likely the results for no sirend sounds with sox sample for you).

The original thread is named "Test your soundcard for clipping" for a reason.  Obviously fb2k + windows mixer settings you use cause clipping for you. Try lowering volume in windows mixer or use fb2k volume control in case the things I suggested in my previous post don't work for you.
Let's suppose that rain washes out a picnic. Who is feeling negative? The rain? Or YOU? What's causing the negative feeling? The rain or your reaction? - Anthony De Mello

Famous udial sample not fixed by Resampler (SSRC)

Reply #4 –
You mean that the siren sound comes from clipping? I always thought that clipping sounds like crackling, static noise. That siren sounds rather clean, just like it would be transpsed down to 10KHz or so.
Anyway, I tried to lower the volumes but it doesn't seem to help much

Famous udial sample not fixed by Resampler (SSRC)

Reply #5 –
Quote
You mean that the siren sound comes from clipping? I always thought that clipping sounds like crackling, static noise.

Generally yes, but this sample is designed in a way that clipping results in very weird aliasing of the siren sound. I've attatched a screenshot to this post. It shows your fb2k resampled uploaded udial version after amplifying by +1dB. All visible sweeps besides the bright one arround 20000Hz are caused by clipping.

If lowering volume (when playing back the version resampled to 48kHz with fb2k) doesn't help, I have no ideas... Maybe there's some weird extra-resampling happening in the soundcard...  - What soundcard is it BTW? Make sure you don't have some option checked in control pannel that forces sound to a different sampling rate then fb2k 's output... In such a case you'll get additional (most likely crappy) resampling again. BTW: How does udial sound without resampling?
Let's suppose that rain washes out a picnic. Who is feeling negative? The rain? Or YOU? What's causing the negative feeling? The rain or your reaction? - Anthony De Mello

Famous udial sample not fixed by Resampler (SSRC)

Reply #6 –
Quote
this sample is designed in a way that clipping results in very weird aliasing of the siren sound. I've attatched a screenshot to this post. It shows your fb2k resampled uploaded udial version after amplifying by +1dB. All visible sweeps besides the bright one arround 20000Hz are caused by clipping.

I see, thanks for clarification.
Quote
What soundcard is it BTW?

It's an integrated CMedia 9738 codec.
Quote
Make sure you don't have some option checked in control pannel that forces sound to a different sampling rate then fb2k 's output... In such a case you'll get additional (most likely crappy) resampling again.

Hmm, I have Sample-rate Conversion Quality set to the Best in control panel (slider all the way right). As for CMedia driver panel, I have all the DSP stuff turned off. I'm using the analog output, but there's some S/PDIF Output setting set to "Digital Audio 48KHz", other possible options to choose are "S/PDIF in Loopback" and "Analog Input"...
Quote
How does udial sound without resampling?

The same as with fb2k resampling - there's that siren sound.