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Test 24/96 vs CD resolution, Help appreciated
2Bdecided
post Sep 8 2003, 11:46
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It would seem the general consensus is that 30-second samples are OK for our purposes (and plenty of others).

I don't know the legal situation if your country re: copying library discs, and paying a fee.

I was suggesting, as a general principle, that it's good to support companies that produce excellent products, and don't restrict the way in which we can use them. It's very bad to take advantage of such companies, because that's a sure way to put them out of business!

all IMO.

Cheers,
David.
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tigre
post Sep 9 2003, 11:38
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Most likely I'll be able to get this DVD from a public library (probably next week). Hopefully I'll be able to create some samples from it.


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Patsoe
post Sep 9 2003, 13:08
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I've spent several hours browsing (real life, that is smile.gif) through the library this afternoon - they have 1852 music DVDs, which aren't searchable by label...

I couldn't find a single Chesky SAD or Classic Records DAD... So, since I already promised to contribute, I'll be looking for a local shop now...

Btw, if anyone is interested, here is a list of Classic Records 24/96 DVD-V discs: http://www.audionautes.com/lp_cd/classicre...dad/dad_eng.htm
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tigre
post Sep 10 2003, 23:46
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Thanks for the help, Patsoe. I'll have a look if the library (browsable online smile.gif ) has got some DVDs from the list.


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tigre
post Sep 10 2003, 23:53
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OK. Finally here's a detailed description of how the test should be performed. Probably most of the explanation isn't necessary for people here, but I just want it to be as fool-proof as possible. B)

===============================


Test CD resolution (16bit/44.1kHz) vs. high resolution (e.g. 24/96)

Test samples
2 short samples are here: http://64.41.69.21/product/reference/keys.wav and http://64.41.69.21/product/reference/triangle-2.wav
Anyone who can get 24/96 material please post short samples (~20 seconds, reasonable volume = peak at -0.1 - -10dB) here: Upload thread

Hardwardware needed: (*)
Soundcard capable of 24/96 playback.

Software needed: (*)
foobar2000 http://foobar2000.org
ABCHR http://ff123.net/abchr/abchr.html (*)
______________________
(*)
for those who have
DVD-A authoring software and a DVD-A player OR
DVD-V authoring software that can handle 24/96 audio and a DVD player capable of DVD-V-with-24/96-audio playback,
instead of ABCHR use KikeG's fileABX to create randomized files and use your authoring software to create DVD-A/V

========================


How to test

0. Install the software needed etc.

1. Take some audio sample(s) recorded at 24/96 = "A" sample(s)

2. Convert "A" to "A_downsampled": 16/44.1 using fb2k's diskwriter, dither (strong noiseshaping), slow resampling

3. Create "B" samples by converting "A_downsampled" to 24/96 using fb2k's diskwriter, slow resampling, dither.

4. Try to hear differences and prove that you hear them by ABXing using ABCHR (**)
________________
(**)
If you want to use DVD-A/V + hardware player:

4.1. Use KikeG's fileABX to create randomized files from "A" and "B"
4.2. Author a DVD-A/V using the randomized files
4.3. Try to ABX = play back with your hardware player and tell which files are "A" and which "B"; compare to fileABX's log

*AFTERWARDS*

=======================


Details/suggestions for "How to test":

Given the directory you want to use for the test is d:\test

0. Install the software needed etc.
- create subdirectories: \test\A_samples; \test\temp; \test\B_samples
- put ABXHR (or fileABX) to d:\test
- install foobar2000 using installer

1. Take some audio sample(s) recorded at 24/96 = "A" sample(s)
- put the samples you want to use for testing to A_samples directory

2. Convert "A" to "A_downsampled" ...
- run foobar2000
- enqueue (e.g. drag'n'drop) all samples from \A_samples to foobar2000's playlist
- highlight all files
- Rightclick -> convert -> Settings ...:
-- Output directory: d:\test\temp
-- Output filename formatting: %_filename%
-- Output format: WAV (PCM 16bit dithered)
-- [x] Use DSP
-- [ ] Don't reset DSP between files
-- [ ] Use replaygain
-- Press "go to DSP settings" (DSP Manager) : Move *ONLY* Resampler (SSRC) to "Active DSPs" window
-- Go to DSP Manager -> Resampler:
--- Target sample rate: 44100 Hz
--- [x] Slow mode
--- close preferences
- Rightclick -> convert -> Run conversion
Finished. Now 44/16 versions of the source file(s) should be in d:\test\temp

3. Create "B" samples by converting "A_downsampled" to 24/96 ...
- clear foobar2000's playlist by highlighting all files and pressing "Del"
- enqueue (e.g. drag'n'drop) all samples from \temp to foobar2000's playlist
- highlight all files
- Rightclick -> convert -> Settings ...:
-- Output directory: d:\test\B_samples
-- Output filename formatting: %_filename%
-- Output format: WAV (PCM 24bit dithered)
-- [x] Use DSP
-- [ ] Don't reset DSP between files
-- [ ] Use replaygain
-- Press "go to DSP settings" (DSP Manager) : Move *ONLY* Resampler (SSRC) to "Active DSPs" window
-- Go to DSP Manager -> Resampler:
--- Target sample rate: 96000 Hz
--- [x] Slow mode
--- close preferences
- Rightclick -> convert -> Run conversion
Finished. Now 96/24 versions of the source file(s) should be in d:\test\B_samples

4. Try to hear differences and prove that you hear them by ABXing using ABCHR (***)
- open ABCHR
- File -> Setup Test -> Load "A" (=Original) and "B" file.
- Press ABX...; choose "Select A" = Original and "Select B" = Sample 1
- Listen to A, B, X (or parts of them) until you think you know if X is A or B and press next trial.
- You can stop when the "Probability you were guessing" is < 1% (8/8 correct trials, 10/11, 12/14, 14/17, 16/20, ...) or give up.
- If you ABXed successfully, provide the result, ideally with a detailed description about the difference you've heard.
____________________________
(***)
If you want to use DVD-A/V + hardware player:

4.1. Use KikeG's fileABX to create randomized files from "A" and "B"
- put fileABX.exe to test folder, e.g. d:\test
- create a set of n test files (at least n=8; something like 20 would be better):
-- given the name of the 1st sample is "sample1.wav" and n=20 the command line is: "d:\test\fileabx.exe

d:\test\A_samples\sample1.wav d:\test\B_samples\sample1.wav 20" (copy + paste if you like)
-- in \session01 subfolder you'll find the test files now. 01_A.wav and 02_B.wav are the reference files "A" and "B",

03_X01.wav, 04_X02.wav ... are randomized copys of either "A" or "B".
- Print the file index.txt for later use.

4.2. Author a DVD-A/V using the randomized files
- Put the tracks in the same order as they are in \session01 folder.
- If you want to try more than one sample just repeat 4.1 and put files from \session02, \session03 ... to the compilation.

4.3. Try to ABX
- play back with your hardware player and tell for each track if it's "A" or "B". You can listen to the reference tracks and

the test tracks as often as you like, also to small parts of it if necessary.
- When you have decided if one track is "A" or "B" write down the result.
- When you're finished compare to results.txt and count how many results were correct. To prove that you hear a difference with > 99% security you need 8/8 correct trials or 10/11, 12/14, 14/17, 16/20, ...
- If you ABXed successfully, provide the result, ideally with a detailed description about the difference you've heard.

==========================

Good Luck!

This post has been edited by tigre: Sep 11 2003, 02:04


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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
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KikeG
post Sep 11 2003, 08:15
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For generating the files, maybe it's a better idea using triangular dither instead of strong ATH dither, because the later can work worse if further processing (such as digital attenuation or eq.) is performed when listening to the files. Also, there's no need to use dither when converting from 16 to 24 bit.

Edit: BTW, you can use WinABX too for the test rolleyes.gif

This post has been edited by KikeG: Sep 11 2003, 08:25
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tigre
post Sep 11 2003, 08:55
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QUOTE (KikeG @ Sep 10 2003, 11:15 PM)
For generating the files, maybe it's a better idea using triangular dither instead of strong ATH dither, because the later can work worse if further processing (such as digital attenuation or eq.) is performed when listening to the files. Also, there's no need to use dither when converting from 16 to 24 bit.

About 16->24 conversion: Dither or not should be equal, so no need to change this - or...?

About noise shaping vs. flat: I thought it's recommended to use flat dither for all steps of processing and noise shaped dither only in the last step (can't remember where I've read that, maybe CEP help or some threads about running winamp with several DSP plugins...). As the source is 24bit there hasn't been (hopefully) a noise shaped dithering step to 16 bit before, so this would be the one and only.
Additionally, if someone is able to hear the difference between 16bit and higher resolution (at low volume parts of a sample, great equipment, silent environment), it should be easier to hear with flat dither used than with noiseshaped as the perceived noise level is lower with noiseshaped (I just want to explain my thoughs - I know that you know these things wink.gif ).

So ... In your statement there's a "maybe" and a "can". This means to me either you're a polite person or it's hard to tell if noise shaping should be used or not. Given someone who uses 24/96 audio for storage/playback probably uses high quality equipment - will this decrease the danger of noise shaped dither giving worse results when processing is applied?
Giving the advice not to use equalizers/further processing in the test is no option as in RL (some) people use DSPs and the test should give RL results.

So - as I have no idea how dangerous noise shaped dither+dsp is compared to flat dither noise becoming audible at low volume, please give more information about this. - Or just tell me what to use. I'm sure you know what you're talking about. smile.gif


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KikeG
post Sep 12 2003, 17:41
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QUOTE (tigre @ Sep 11 2003, 08:55 AM)
About 16->24 conversion: Dither or not should be equal, so no need to change this - or...?

No, in practice there will be no difference, so for sake of simplicity you can leave it on.

QUOTE
So ... In your statement there's a "maybe" and a "can". This means to me either you're a polite person or it's hard to tell if noise shaping should be used or not.

Well, it means that I'm not really sure, and for some things I don't like to be very categorical.

QUOTE
Given someone who uses 24/96 audio for storage/playback probably uses high quality equipment - will this decrease the danger of noise shaped dither giving worse results when processing is applied?


Probably not. Dither break would happen just if you further process the samples with a resolution of 16 bit, or process them at 24 bit or more and then dither/truncate to 16 bit. I don't think this will be usual when listening to 24/96 samples. Also, I guess that in practice the kind of dither won't make much of a difference, because I believe flat dither noise won't be audible under regular listening conditions. Note that I was suggesting triangular shaped dither, which is a little bit less noisy than flat dither, but more resistant to processing than strong ATH shaping.

Personally, I use triangular shaped dither when listening to music, because I don't like the idea of having such higher noise levels at high frequencies. I prefer a more uniform noise distribution, even when it would be more audible under critical conditions. As I can't hear this noise anyway, I use it. But it's more of a "fuzzy feeling" thing than anything else, because in practice there's probably no difference. But being rational now, under unrealistic critical listening conditions, strong ATH would most probably be better. (sorry for not being categorical, I can't avoid it smile.gif )

So, use what you prefer, I guess strong ATH is fine for the test.

This post has been edited by KikeG: Sep 12 2003, 18:00
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Pio2001
post Sep 16 2003, 20:57
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QUOTE (KikeG @ Sep 5 2003, 04:50 PM)
AFAIK it has been tested that hf inaudible tones don't intermodulate inside the ear and cause audible tones, but I could be wrong. So... I don't know that much.

I ran one of these tests (playing an audible frequency in one speaker and an inaudible one in the other speaker). It was very short, I just tried 6 kHz and 18 kHz and heard nothing else than 6 kHz. That's all. The playback was loud, enough to cause intermodulation in the speaker if the two tones are played into the same one. But I would probably have heard no intermodulation either with two audible tones. Ear intermodulation must occur at high levels (>100 dB). The test just showed that the common intermodulation comes from the hifi equipment and not the ear.
Nika Aldrich also ran the same kind of test (his forum : http://recpit.prosoundweb.com/viewforum.php?f=18)
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nwn
post Sep 16 2003, 22:14
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i see you look for 24/96 sound file ..
here perhaps no expensive ..
http://www.aixrecords.com/catalog/sampler2.html
Mlp and Pcm files..

i don't see such file here .. http://www.kellyindustries.com/sounds.html


and this http://www.chesky.com/catalog/body_catalog...0010&CATEGORY=2 is on a d*nk** p*p network .. with some others ..

but you know as there are dvd-audio, envy 24ht and Audigy have restriction and degrade output signal desactivating digital output .. licence ...
http://www.dtcp.com/data/Compliance_Rules_...udio_020610.pdf


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askoff
post Sep 18 2003, 19:08
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QUOTE (Pio2001 @ Sep 16 2003, 11:57 AM)
It was very short, I just tried 6 kHz and 18 kHz and heard nothing else than 6 kHz. That's all.

I can hear 18 kHz sine wave. With my SB Live and without resampling and tone samplerate is 44,1 kHz. laugh.gif
(well maybay i don't hear that 18kHz wave but all that distortion...)
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tigre
post Sep 23 2003, 23:32
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OK. I've got a DVD-V containing 24/96 PCM audio now.
[Edit]
Blah ... I had some problems extracting audio using smart ripper but probably I've found a sollution.
[/Edit]

Another point that just came to my mind: IIRC when ripping DVD-V (e.g. to DivX + mp3 audio .avi files) sound is often low volume and needs to be amplified (or was it AC3 sound only ...?). If this is the case here too, some of the 24bits resolution could be lost. (I don't think there's a difference between 24 and e.g. 22bit but the design of this test shoud satisfy audiophiles as well ... rolleyes.gif .) So - is there a way to get sound from DVD-V at decent volume without loosing resolution due to amplifying?

This post has been edited by tigre: Sep 23 2003, 23:37


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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
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tigre
post Sep 24 2003, 01:12
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OK. Finally I've managed to get 24/96 audio from the DVD-V "Chuck Mangione - The Feeling's Back" I've linked to some posts earlier. FYI: I've used LPCM24.exe from rarewares.

It contains music-related content > 24kHz and according to CEP's frequency analysis noise level is somewhere arround -108dB. Volume is reasonable -> from CEP statistics of 1 randomly chosen track:
CODE
Max Sample Value: 27755.65
Peak Amplitude: -1.44 dB
Minimum RMS Power: -70.73 dB
Maximum RMS Power: -8.69 dB
Average RMS Power: -22.1 dB


It's a jazz record, instruments are:
Flugelhorn
Piano
Acoustic guitar
Drums
Percussion
Acoustic bass, electric bass
Cello
Flute, ato flute
female vocals

Tomorrow I'll start to create some test samples of it. I'd appreciate any thoughts/wishes about what kind of samples to choose (as much high frequency content as possible / high dynamic range within the sample / many instruments playing at the same time / only one or few instruments / certain instruments playing / strongest available transients / ... ?).

Bedtime now. CU.

edit: typos

This post has been edited by tigre: Oct 4 2003, 08:39


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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
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KikeG
post Sep 26 2003, 08:02
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I think a good test sample could be one that would have as many variety as possible. For example, sample containing a soft part with a single instrument playing, and then a louder part with several instruments. But I don't mean editing, just getting a piece of the recording that encompasses all these.

Still downloading your 1st. sample...
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Patsoe
post Oct 3 2003, 22:34
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QUOTE (Patsoe @ Sep 6 2003, 10:40 PM)
This disc should be of great help: http://www.chesky.com/catalog/body_catalog...0010&CATEGORY=2 - unfortunately I can't find it at the library. Heck, I'd buy it if I could find it at all in Holland...

I finally got my hands on it: CHDVD171 "The Super Audio Collection and Professional Test Disc" from Chesky. Would you still need some of that, Tigre?
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tigre
post Oct 4 2003, 08:38
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Hi Patsoe.

It would be good to have more samples, because all samples that I've uploaded are similar somehow. I hope there's something completely different on your CD ... Maybe you find something with a single (a few) instrument(s) playing, something acapella-like and/or something with huge dynamic range ...?

Besides, since it's called "The Super Audio Collection and Professional Test Disc" maybe there's some information in the booklet about mastering, e.g. what equipment used etc. This could help to persuade some people that the quality of these recordings is good enough for this test.

Thanks. CU tigre


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