Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Audio DiffMaker freeware for checking for equipment effects
Audio DiffMaker freeware for checking for equipment effects
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th June 2009, 11:32 PM   #11
bwaslo is offline bwaslo  United States
Old guy with soldering iron
diyAudio Member
 
bwaslo's Avatar
 
Join Date: May 2006
Location: Portland, Oregon!
Audio DiffMaker freeware for checking for equipment effects
No, nothing that smart, though that would be a good idea.

Probably just end trimming that gets done on the one version of the file, by the matching-up process. When it is setting up to do the trial and error thing to line things up in time, or to tweak sample rate (even if it ends up not having to do it) it needs some breathing room to shift back and forth within. I THINK that's what you're hearing.

That won't affect the usability, of course, though.

I did some tests with some 24/96 files I got from the Linn web site, comparing them to versions converted to 44/16. Got about the deepest nulls of any (other than identical file copies, of course, or comparing "original" with "CD copy" files)
  Reply With Quote
Old 11th June 2009, 02:02 AM   #12
andy_c is offline andy_c  United States
Banned
 
Join Date: Apr 2003
This thing is a fantastic tool. I've recently discovered that one can rip DVD-A discs using some programs available on BitTorrent. Back in 2003, I got a universal player and a bunch of DVD-A discs. One of those was Workingman's Dead. The sound quality of this DVD-A blew away the CD and LP, but I always wondered whether this was due to Mickey Hart's excellent remastering or the high resolution of the format. I've since gone to computer audio, and all my files are 16/44.1. I haven't been able to play a rip of this DVD-A until now. But was I sacrificing sound quality by downsampling to 16/44.1?

I did an experiment. I ripped a couple of songs from this album to their native 24/96 format. Then I downsampled them to 16/44.1 using a program called r8brain, at the highest quality setting. Using the same program, I upsampled the downsampled file back to 24/96, then subtracted this file to the original using Audio Diffmaker.

In order to hear anything at all in the difference file, I had to turn the volume all the way up and put my ear almost right on the tweeter. I could hear only hiss, except for one spot where there was a very audible "click". This ticked me off. I wasn't sure how to fix it.

Then, while reading a thread on hydrogenaudio.org, I found out about a program called sox. There's another fantastic program! I tried downsampling the same 24/96 files from Workingman's Dead to 16/44.1 using sox. The first thing I noticed was that it gave me a warning, saying that digital clipping had occurred in the downsampling. So I tweaked a scale factor until it just barely went away. Then I upsampled the resulting file back to 24/96. I again got a warning about digital clipping. So I tweaked a scale factor again until it just went away for the upsampling as well. Then I subtracted this 24/96 file from the original 24/96 file using Audio DiffMaker. It found the correct scale factor for the subtraction, and actually gave me a deeper null than what I got when doing the resampling using r8brain.

Then I listened to the difference file. What I got was only a little hiss with the volume turned all the way up. No click! So Audio DiffMaker uncovered a fault in the r8brain resampling software. DiffMaker always reported a scale factor of 0 dB for the r8brain files, so r8brain apparently does not scale to prevent digital clipping. I think that's where the click is coming from. I'm now using sox exclusively, and tweaking the scale factor for each individual track to just avoid digital clipping.

Thanks so much for this tool. It found the r8brain problem, and also told me that the "magic" of the Workingman's Dead DVD-A was due entirely to the remastering, not the 24/96 format at all. All in all, it was time very well spent.
  Reply With Quote
Old 11th June 2009, 03:15 AM   #13
scott wurcer is online now scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: Belmont MA
Quote:
Originally posted by andy_c
the "magic" of the Workingman's Dead DVD-A was due entirely to the remastering, not the 24/96 format at all.
A bit of agit-prop I say.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 11th June 2009, 02:13 PM   #14
scott wurcer is online now scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: Belmont MA
Andy a serious question. The guy who wrote r8brain says that the PRO version makes higher quality files than the free version. Your results would seem to put any difference "in the noise" unless of course you used the PRO version?
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 11th June 2009, 03:09 PM   #15
andy_c is offline andy_c  United States
Banned
 
Join Date: Apr 2003
Hi Scott,

I used the freeware r8brain version with quality set to "very high" (the highest settinig). The results in the difference file were "in the noise", except for the occasional clicks that were quite a bit higher than the noise. I'm assuming this was due to clipping that wasn't detected or corrected for. I've stopped using it because of this. When running DiffMaker, the scale factor DiffMaker computed was always 0 dB with the files that were converted by r8brain, so this seems to indicate that it does no scaling to prevent clipping.

Here's a sample sox command line I used for the downsampling:

sox -v 0.963 track-01-01[0]-01-[L-R]-24-96000.wav -b 16 -r 44100 "01 - Uncle John's Band.wav" dither

The funky WAV file name was automatically generated by DVD-A Explorer, which I used to rip the DVD-A. -v is the volume, -b is number of bits, -r is the sample rate, and "dither" specifies the default dither which is triangular PDF. In this case, I kept trying different values of volume, like 0.99, 0.98, 0.97, and 0.96. Once I figured out that 0.96 eliminated clipping and 0.97 didn't, I did increments of 0.001 to find the largest one that had no clipping. So in this case, 0.964 would cause clipping. I know this is overkill, but hey, this is audiophilia . When using sox to do the sample rate conversion, the results in the diff file are only random noise, no clicks at all. Sox is fantastic. I haven't even begun to explore its possibilities.
  Reply With Quote
Old 12th June 2009, 01:25 AM   #16
scott wurcer is online now scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: Belmont MA
Thanks for the tip SOX looks great, and has a nice tutorial on how MATLAB was used to study its algorithms. Open source rules!
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 13th June 2009, 07:42 PM   #17
andy_c is offline andy_c  United States
Banned
 
Join Date: Apr 2003
Quote:
Originally posted by scott wurcer
Thanks for the tip SOX looks great, and has a nice tutorial on how MATLAB was used to study its algorithms. Open source rules!
Cool! I will have to read that. Meanwhile, looks like I posted a command line above that's not optimum for this application. Here's the command line:

Quote:
sox -v 0.963 track-01-01[0]-01-[L-R]-24-96000.wav -b 16 -r 44100 "01 - Uncle John's Band.wav" dither
It turns out there's a better way. Sox uses "options" and "effects". In this case, the "options" are the command-line elements that precede the name of the relevant file (input or output file). The "effect" goes at the end. In this case, "dither" above is an "effect". But it turns out that if you specify -r and the sample rate before the output file name, this implicitly invokes the "rate" effect with the default "rate" options. If instead you explicitly invoke "rate" as an effect at the end, you get options that aren't available when specifying -r before the output file name. The important option here is the conversion quality. It defaults to "high" if you use -r before the output file name, but if you explicitly invoke "rate" as an effect, you can specify "very high" as the conversion quality. Here's the command line for that.

sox -v 0.963 track-01-01[0]-01-[L-R]-24-96000.wav -b 16 "01 - Uncle John's Band.wav" rate -v 44100 dither

The "-v" after "rate" (not to be confused with the -v volume option) is the "very high" conversion quality option. This makes the determination of the volume setting very time-consuming because this option slows down the conversion a lot. But I've found that if you determine the volume using -h (the default "high" option for the rate effect), the required volume setting comes out exactly the same as for -v, but is much faster. At any rate (no pun intended ), I save all my command lines to a batch file in case I need to re-run the conversion. This has already come in handy, as when I discovered the -v option, I decided to re-convert all my DVD-A's using -v. Since I have the batch files, this is pretty easy and quick. Here's my batch file for converting Workingman's Dead.

sox -v 0.963 track-01-01[0]-01-[L-R]-24-96000.wav -b 16 "01 - Uncle John's Band.wav" rate -v 44100 dither
sox -v 0.994 track-01-01[0]-02-[L-R]-24-96000.wav -b 16 "02 - High Time.wav" rate -v 44100 dither
sox -v 0.991 track-01-01[0]-03-[L-R]-24-96000.wav -b 16 "03 - Dire Wolf.wav" rate -v 44100 dither
sox -v 0.976 track-01-01[0]-04-[L-R]-24-96000.wav -b 16 "04 - New Speedway Boogie.wav" rate -v 44100 dither
sox -v 0.988 track-01-01[0]-05-[L-R]-24-96000.wav -b 16 "05 - Cumberland Blues.wav" rate -v 44100 dither
sox -v 0.996 track-01-01[0]-06-[L-R]-24-96000.wav -b 16 "06 - Black Peter.wav" rate -v 44100 dither
sox -v 0.995 track-01-01[0]-07-[L-R]-24-96000.wav -b 16 "07 - Easy Wind.wav" rate -v 44100 dither
sox -v 0.989 track-01-01[0]-08-[L-R]-24-96000.wav -b 16 "08 - Casey Jones.wav" rate -v 44100 dither

Oh, and one more thing. This site has quality comparisons for many different ASRC software implementations. It looks like sox with the -v rate option is about as good as it gets.
  Reply With Quote

Reply


Audio DiffMaker freeware for checking for equipment effectsHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Unloading audio equipment Magnetmaz Swap Meet 5 18th October 2007 10:54 PM
Pro Audio Equipment In the Home CARTRulz Subwoofers 59 25th June 2006 05:09 PM
DIY Audio Effects Processor Books? orson198305 Everything Else 2 10th June 2006 08:43 AM
freeware Audio analyzer for Windows Andy F Multi-Way 0 22nd July 2003 07:37 PM


New To Site? Need Help?

All times are GMT. The time now is 12:33 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki