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Topic: ABX Comparator version 2.0 (Read 51318 times) previous topic - next topic
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ABX Comparator version 2.0

Reply #75 –
Hello Peter,

First I apologize for my poor english.

Thanks for this useful component.
He is very efficient to compare versions with tempos not very different
For example I use it to compare the same track with different qualities (compression or sampling rate). It’s very interesting.

But, when two versions have very different tempos the comparison is not significant.
I suggest when we select the option “keep playback position when changing track” you add another option to keep the same "relative" position when you change track.

For example: if a want compare to versions of Mozart piano concerto 21 – 2 andante
A – Performer : Barenbouim  duration 8:37
B – Performer : Zacharias duration 5:13
When playing the track A, at time 4:18 (half time) , I switch to track B, the playback will continue at time 2:36 (half time). The comparison is more significant. (if the tempos are relatively constant)

With this option we can compare the last seconds of two versions even if the tempos (the duration) are very different.
Regards

ABX Comparator version 2.0

Reply #76 –
Version 2.0 final posted on the components site.

As for pending feature requests, please keep them coming, at some point there will be a 2.1 adding more features.
Microsoft Windows: We can't script here, this is bat country.

ABX Comparator version 2.0

Reply #77 –
I've been away from this thread for awhile, but I just now loaded 2.0 and inserted two completely dissimilar songs of different lengths, merely to familiarize myself with what's new. Listened briefly, didn't do a trial run first, played around with the phrase repeat function, didn't like that my keyboard up and down buttons seemed to inconsistently move the song position when selecting the "stop" point {allowed down in .1 second increments, only, but not back up, I believe}, checked to see if you can select a stop point before you select a start point, voted on the first trial, then just filled up the remaining 7 trials by voting B,B,B,B,B,B, and B as rapidly as possible without even listening to ANYTHING [wondering if that's what triggered this oddity]. I guess there's the possibility of just dumb luck, but check this out:
Code: [Select]
foo_abx 2.0 report
foobar2000 v1.3.3
2015-01-09 13:37:46

File A: 03 -Valentine.mp3
SHA1: 77be0c40823faec83c2a4354ca44df1a0f89f394
File B: 01 - Susie Q.mp3
SHA1: 48019278233fb9efa8e39a7c4d7b030525561216

Output:
DS : Primary Sound Driver
Crossfading: YES

13:37:46 : Test started.
13:38:21 : 01/01
13:42:54 : 02/02
13:42:56 : 03/03
13:42:57 : 04/04
13:42:58 : 05/05
13:43:00 : 06/06
13:43:02 : 07/07
13:43:21 : 08/08
13:43:21 : Test finished.

 ---------- 
Total: 8/8
Probability that you were guessing: 0.4%

 -- signature -- 
54efa110200c9339dfafd3eab5bfa6d54894ebef


http://www.foobar2000.org/abx/signaturecheck

Will try again.

edit to add: Tried again 3 times and got expected random results. I have no idea what happened. .4% means the odds this happened by fluke is 4 in 1000, or 1 in 250, right? Admittedly, I did listen for trial 1 , so in truth only trials 2 through 8 were random stabs, but still seems odd. Was this just a freaky coincidence?

 

ABX Comparator version 2.0

Reply #78 –
Yeah, given 2s per trial, 8 trials per test, you should see such a result roughly each hour of nonstop random button clicking.
"I hear it when I see it."

ABX Comparator version 2.0

Reply #79 –
I started using the ABX module V2.0 for Foobar V1.3.7.  I noticed a difference in switching time when going from one of the inputs to X when the input was the version as X in that trial.  Because of that difference in switching time I was able to pick out the correct choice 16 out of 16 times based on time alone.  The two selections were identical except for sample rate.  The original was 88K and the downsampled version was 44.1K.  the switching time between the original that was actually X and X was shorter than the switching time between the non-X original and X.  Has anyone else noticed this?

ABX Comparator version 2.0

Reply #80 –
If I'm getting you correctly, are you sure the problem is not actually that your two samples aren't properly time aligned? I just demonstrated that I can hear a 10ms or so difference in the audio files in the AVSforum's AIX records test due to such a time alignment problem.  This completely escaped the creators of the test when they did the down conversion  and I wouldn't be surprised if it escaped Bob Stuart's attention in his recent AES paper declaring CD "not transparent".

ABX Comparator version 2.0

Reply #81 –
If mzil's hunch isn't correct your finding is troubling, TomPer. When sample rates don't match the component reinitializes sound device between all playback switches already. If it's not an error in the file it means your device opens some rates faster than the others.

ABX Comparator version 2.0

Reply #82 –
I've always thought the best practice was to test the effect of low-pass filtering, without actually re-sampling. Because, except for the aliasing of frequencies above Nyquist frequency (thus requiring low-pass filtering) , re-sampling is assumed to be transparent.

A 2nd test, would be low-passing both A and B, but re-sampling only one of them. Preferably 2 times (down and then restored). This will simply test that the re-sampling process is in fact transparent as long as nothing needs to be cutoff because of the Nyquist frequency.

The 3rd option, is the playback of files at different samples rates. I've always believed that some devices might "behave" differently at specific sample rates. So while it's still an interesting test to note if there is such difference. I think the previous two tests should be considered before. That way you'll notice if what you are sensing as different is coming from:
a) The low-pass filter, which is a process you still need to do.
b) The re-sampling, which is another process you will be doing.
c) Finally, if the two tests above are transparent, then there's something about how your setup tackles playback at different frequencies.

ABX Comparator version 2.0

Reply #83 –
I just re-ran the test to provide more info.  The same two files were used and the start point was at a place that had significant output to make the transition point easier to identify.  In all the trials, the time when going from the A or B selection that was actually X was about half the time of that when going to X from the non-X selection.  This was not a case of a difference in the point of the music selection, but rather the start of any sound coming out of the application after the X button was pressed.  In this test I listened directly from the headphone output of my PC to minimize the number of devices in the chain.  In the previous tests I went from the USB output to a USB to SPDIF converter and then to my audio system.  In both cases the delay appeared to be the same.

ABX Comparator version 2.0

Reply #84 –
TomPer, would you be so kind as to share two 30 seconds or less files, prepared in the exact same fashion as the ones you are noticing this problem, so as to let others test it out on their systems. It may be gear dependent. Thanks. [We have an upload section on the forum for this very purpose.]

http://www.hydrogenaud.io/forums/index.php?showforum=35




ABX Comparator version 2.0

Reply #85 –
I will do that later today.  I forgot to mention that when I re-did the test I got 16 out of 16 correct just on the delay alone.  This test was confirmed by a friend who is very involved in audio and builds high quality amplifiers so he does a lot of critical listening.

ABX Comparator version 2.0

Reply #86 –
My sound card performs a fade-in when ever you play a different sample rate from previously.

If the two files have different sample rates, then it's easy to tell them apart. Simply click X, stop, A. If A fades-in A=Y, if A starts cleanly A=X. There's nothing foobar2k can do about this.

Quote
foo_abx 2.0 report
foobar2000 v1.3.6
2015-01-16 14:49:59

File A: 44.1.wav
SHA1: 2bdb598523e3685fe4a680ea70ae3f7d3bc6d31e
File B: 96.wav
SHA1: bf4ac807fc55e76f7557c30a29abe5b990159d64

Output:
DS : M-Audio Delta AP Multi, 16-bit
Crossfading: NO

14:49:59 : Test started.
14:50:39 : 01/01
14:50:47 : 02/02
14:50:51 : 03/03
14:50:56 : 04/04
14:50:59 : 05/05
14:51:04 : 06/06
14:51:08 : 07/07
14:51:15 : 08/08
14:51:15 : Test finished.

----------
Total: 8/8
Probability that you were guessing: 0.4%

-- signature --
46511a38eb9f47a201f2fa3e2cd46d616e5c46b8


EDIT: the two files I tested both consist of a 1 second long stereo 16-bit -6dB 1kHz tone. The only difference is the sample rate. I haven't tried different output modes or OSs.

Cheers,
David.

ABX Comparator version 2.0

Reply #87 –
The ABX comparator could play digital silence at a third sample rate before resuming playback. Then your sound card would always perform a fade-in.

ABX Comparator version 2.0

Reply #88 –
abdecided and foosion are both correct.  The requested files have been uploaded.  I used two PCs to repeat the test.  One is an older IBM (Lenovo) Thinkpad X60 s with a SoundMAX integrated HD audio sound card.  The second is an HP Envy with i7 4710  quad processor, at 2.5GHz and 16 gB RAM and a Realtek High Definition audio card.  Both are running Windows 7 Pro with all the latest patches.  The best way I have found to identify this is to repeatedly go back and forth between A and B until you are familiar with the delay which is the longer delay.  The repeatedly select A to become familiar with the short delay that occurs with no sample change.  At that point you only need to toggle between A and X.  If the delay is short, X is A.  If it is long, X is B.  With both PCs I was able to score 16 out of 16 correct only going between A and X.

ABX Comparator version 2.0

Reply #89 –
After further testing I have come to the conclusion that in its current form the ABX test module in not usable for my current testing.  I re-tested listening to A only, then put a long manual pause in before selecting X.  However, after I had learned the timing differnece when a sample rate change occurred I was able to correctly identify X 14 out of 14 tests based solely on the delay differences even with a long variable time delay.

I have been doing double blind tests for around 20 years and realize how critical it is to eliminate all clues that could identify the outcome based on anything other than sonic differences.  The QSC ABX test device I use had such a problem.  The switching relays were physically located on different areas of the PCB.  If you were close enough to the display to see the A and B designations during the test you could learn the differences in the sound of the relay swithcing.  If the test passages were low in volume it allowed a person familiar with the relay switching sounds to identify X 100% of the time based solely on switching sounds.  To correct this I built a sound absorbing enclosure and a large display that would allow the switch box to be located a far distance from the person conductiong the tests

Hopefully this condition will be resolved because the comparator is of no use to me at this point for running tests with different sample rates.

ABX Comparator version 2.0

Reply #90 –
Perhaps you are hearing the timing difference in the files you are testing. They seem to have a few sample offset difference and that can be enough to differentiate them. If you resample with lvqcl's SoX based resampler there shouldn't be offsets. Or you could manually fix the files.

ABX Comparator version 2.0

Reply #91 –
The difference does not appear to be in the music itself, but rather in the time that any sound at all appears.  It is quite different when the sample rate changes.  2Bdecided noticed it with a constant sine wave when the sample rates were different.

ABX Comparator version 2.0

Reply #92 –
Quote from: foosion on
The ABX comparator could play digital silence at a third sample rate before resuming playback. Then your sound card would always perform a fade-in.

If it does the same fade in regardless of sample rate, this would work. No guarantee that this is always the case.

Cheers,
David.

ABX Comparator version 2.0

Reply #93 –
I finally tested different sample rates and indeed the varying delay invalidates the test. Seems to happen at least with WASAPI and DirectSound outputs and with both Microsoft and third party drivers on various sound cards/DACs. The delay seems to be the longer the higher the sample rate is. I think a workaround for this would be to initialize the device to both samplerates one after another on track change. I assume that would keep the delay constant. Not sure what it would do to 2Bdecided's fading.

ABX Comparator version 2.0

Reply #94 –
The delay to me seemed to be longer when changing rates regardless of which way the rate change went.  I did not notice a longer delay when going from 44 to 88 than when going from 88 to 44.  The delay was shortest when no rate change occurred and longer when any rate change was necessary by the processing hardware.  If the intermediate step could be programmed in it would be a great help to me.  I am in the middle of writing  a magazine article on the audability of different sample rates and I must have a reliable double blind testing methodology to do it.

ABX Comparator version 2.0

Reply #95 –
I recently completed a test where I took the 88K file I was using, resampled it to 44K and then resampled that file back to 88K.  I then ran an ABX test and noticed no difference in the switching ( actually I should say playback start) times.  My result was 6 out of 16.  I clearly could not hear a difference.  It would be a great help iin my work if the comparator could be modified to have the previously suggested third non-related sample rate blank segment inserted each time a switch is performed.  Is that a possibility?

ABX Comparator version 2.0

Reply #96 –
Quote from: TomPer on
I recently completed a test where I took the 88K file I was using, resampled it to 44K and then resampled that file back to 88K.  I then ran an ABX test and noticed no difference in the switching ( actually I should say playback start) times.  My result was 6 out of 16.  I clearly could not hear a difference.  It would be a great help iin my work if the comparator could be modified to have the previously suggested third non-related sample rate blank segment inserted each time a switch is performed.  Is that a possibility?

Why don't you just use your favourite audio editor and insert 2 seconds of silence at the beginning of the primary file. Then convert the primary file to anything you want. I would think that this two second silence would more than compensate for any "switching" delays.

ABX Comparator version 2.0

Reply #97 –
Actually, that would not work.  Even with long delays of different times I was able to identify whether the file switched was a new sample rate or the existing sample rate 100% of the time.  The problem is that you learn the different start delays that occur when the rate between a known and X is the same and different.  The clue is the time it takes from when you push the button to make the selection until the music starts.  Once you become familiar with those different delays from initiation to music you can pick the correct answer every time.

ABX Comparator version 2.0

Reply #98 –
Is the idea that foosion had to switch to a third sample rate in an interim step a possibility or is that change a dead issue?
 

ABX Comparator version 2.0

Reply #99 –
Patience. Peter is very busy with multiple projects but he has promised improvements for this component.