Author Topic: Click Removal for DSD files  (Read 6779 times)

dtc

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Click Removal for DSD files
« on: May 07, 2014, 04:14:41 pm »
New user. Several questions about DSD and flac files.

When doing click removal on DSD files, is the file converted  to PCM. If so, what bitrate does it convert to in order to do the click removal?  I am starting with 5.6 MHz DSD files.

I took a 5.6 MHz DSD file and did click removal on it and when I tried to save it, it said it would save it as 176 KHz flac, but it actually saved it as 96 KHz flac. It could  save it as 176 KHz wav, but I found no way to save at 176KHz flac.  Is 96KHz the limit of flac or did I miss an option somewhere?

Thanks.

Paul Sanders (AlpineSoft)

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Re: Click Removal for DSD files
« Reply #1 on: May 07, 2014, 06:47:25 pm »
Hi,

The DSD file is only converted to PCM when you save as PCM.  It's converted to PCM on the fly for click removal, but since only click repairs are saved by this process, that fact is incidental.

The FLAC file business sounds like a bug, but I wouldn't save a DSD recording above 96 kHz in any event.  Above that rate, DSD generates a lot of high-frequency noise (and nothing is gained).  Despite the high sampling rate of DSD, the useable high-frequency response is less impressive than you might expect:

http://www.thewelltemperedcomputer.com/KB/DSD.htm

dtc

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Re: Click Removal for DSD files
« Reply #2 on: May 07, 2014, 11:58:48 pm »
Hi,

The DSD file is only converted to PCM when you save as PCM.  It's converted to PCM on the fly for click removal, but since only click repairs are saved by this process, that fact is incidental.


Thanks Paul.  I am still trying to understand the process.

As I understand it, you cannot save the click corrections  in  DSD format -  correct? The whole file gets has to changed to PCM to change click corrections.  If you cannot save a click corrected DSD in DSD format,  the fact that the whole file can only be saved as  PCM does see to be an important point. 

Can you tell me what sample rate PCM the 5.6 MHz DSD is converted to in order to do click removal? I understand your comment about high frequency noise in DSD, but I would still like to try a higher PCM rate. But, if the DSD is converted to 88 or 96  KHz for click removal, then saving at a higher rate is really just up-sampling. The dialog box that I get in fact says that the click corrected DSD will be saved as 176 KHz flac , so I wonder if that is the PCM rate that is used for click removal of a 5.6 MHz DSD file.

The ideal of course would be to have the click corrections does as PCM, with just those small sections changed, and then the changes merged back into the DSD files, since, as you say, they are only very small parts of the file. Any chance that will happen?


As to saving a 172 KHz flac, it is my understanding that the wav conversion settings are suppose to be used in saving a flac file. Is that correct?

Thanks for helping me work through the process.

dtc

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Re: Click Removal for DSD files
« Reply #3 on: May 08, 2014, 12:25:41 am »
One more time. Are you saying that the click detection and fixes are done separately and saved separately and are only incorporated  back into a file when it is saved? That would mean the major  DSD to PCM conversion is done only when the file is output and that the click fixes are integrated at that time. Correct?  So, if I were able to save at 176 or 352KHz  KHz,  then the parts that do not need fixing will be converted to that sample rate for output and the fixes incorporated on the fly for output. As I reread your answer, that is what it sounds like.

The issue is I want to check the sound of the DSD part  of my DAC versus the LCP part. One option is to convert the DSD to PCM for click fixes and then convert that back to DSD for playing. Not optimal but an option. Fixing the clicks in the DSD file would be the best solution, but I understand that is hard.

Thanks for your help.

Paul Sanders (AlpineSoft)

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Re: Click Removal for DSD files
« Reply #4 on: May 08, 2014, 09:41:11 am »
Yes, your summary of how VinylStudio's click repair process works is correct.  The repairs cannot be saved as DSD, unfortunately.  We were unable to 'splice' the repairs into the original file without audible glitches.

dtc

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Re: Click Removal for DSD files
« Reply #5 on: May 08, 2014, 12:47:17 pm »
Got it. Thanks. Also, it is good to know you tried staying in the DSD format. Obviously, the difficulty of editing DSD files is one major drawback of the format.

If my goal is to have a DSD file at the end, would you recommend starting with a PCM file, say 172 KHz, doing the click removal, and then converting the click removed file to DSD, rather than starting with DSD, removing clicks and saving as PCM and then coverting back to DSD? It seems your concern about high frequency noise may be minimized by starting with PCM rather than DSD. For tracks without a lot of clicks, I can obviously just start with a DSD file.

Thanks for you help. It is much appreciated.

Paul Sanders (AlpineSoft)

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Re: Click Removal for DSD files
« Reply #6 on: May 08, 2014, 01:50:13 pm »
Hi,

Yes, I would start with a hires PCM file.  These hold more high-frequency information that single rate DSD, certainly, and conversion from DSD to PCM is an inherently lossy process.  VinylStudio cannot do the conversion to DSD unfortunately.

dtc

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Re: Click Removal for DSD files
« Reply #7 on: May 08, 2014, 02:03:19 pm »
Thanks Paul. I think I will try starting with PCM.  I can do PCM to DSD conversion with J River, although it would be nice if Vinyl Studio had that feature. It would be one less step for me.   I still need to do some more comparisons between hires PCM and 2x DSD. OF course, the final sound probably has as much to do with the DAC as it does with the format.

FYI - I just started using a Korg MR-2000s with the input modified by Busman Audio. The 5.6 MHz DSD played back by the Korg is very, very close to the original vinyl.