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Digitizing mono vinyl: using phase-inversion to reduce noise
cliveb
post May 10 2007, 23:17
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QUOTE (2Bdecided @ May 10 2007, 10:36) *
My home audio set up is currently in pieces, and I don't have a "mono record, recorded in stereo, declicked and decrackled, but not yet converted back to mono" to test.

(I'm ashamed I haven't got a single archived track to test this on, but I have never saved the result at this stage!)

I've just had a poke around and unfortunately, like you, I don't have any intermediate results saved - only the final files after the mixdown to mono. Whats more, those mono LPs were ones I did for someone else, so I no longer have the actual vinyl to hand. I don't actually own any mono records of my own at the moment.
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AndyH-ha
post May 11 2007, 05:44
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I have a segment of that recording, declicked, that doesn't seem too bad. However, it is in 32 bit floating point, my normal working format, and the size is 11meg+, an all day upload via this dial-up connection. It would be easier if resampled to 16 bit, but still pretty large. An mp3 version would obviously be easier yet. I need to know what you think you need to work with.

I also need to know where to send it. In another recent thread where this topic came up, cliveb said he just put whatever was involved as an attachment to his post. I find no option to allow that. Several other people also complained they see no way to do more than post a link (good only if one has someplace to which to link). Those in the know remained dumb to their pleas.
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cliveb
post May 11 2007, 08:48
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QUOTE (AndyH-ha @ May 11 2007, 05:44) *
I also need to know where to send it. In another recent thread where this topic came up, cliveb said he just put whatever was involved as an attachment to his post. I find no option to allow that. Several other people also complained they see no way to do more than post a link (good only if one has someplace to which to link). Those in the know remained dumb to their pleas.

As you're composing your reply, there's a box labeled "File Attachments". Hit the Browse button to navigate to the file you want to attach. Then click the "Add this attachment" button. You should find after this that the file is listed in a panel within the "File Attachments" box. To actually put it in your posting, you need to click the "Add into Post" button. (Note: I don't think these options are available if you use "Fast Reply").
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cliveb
post May 11 2007, 09:51
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QUOTE (2Bdecided @ May 10 2007, 10:36) *
If you can test a real recording in foobar2k, or upload a 30 second extract of a mono restoration, just before the final mixdown to mono, so I can test it myself, that would be great.

OK, I fished around in the attic and did find a few mono records, so I've recorded a short section from one for you to play with. (If you're interested, it's an extract from Mozart's Flute Concerto No 2. Recording was made in 1958). Bear in mind that this is a straight recording - I haven't done any declicking/denoising at all. My understanding is that your goal is to compare the effect on background noise of a straight mixdown to mono against Foobar's "keep centre channel" plugin, so I'd have thought the fact that this hasn't been declicked shouldn't affect the outcome of that. I deliberately picked a quiet section so that the surface noise is very obvious.

Attached File  mozart.flac ( 1.26MB ) Number of downloads: 183
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AndyH-ha
post May 11 2007, 19:35
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No, there is no such box. Does its existence depend on some browser plug in or having Active-X enabled?
I'm well familiar with the general procedure for making attachments. There just isn't any such option that I have ever been able to find on this particular forum.
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woody_woodward
post May 11 2007, 21:50
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QUOTE (AndyH-ha @ May 11 2007, 11:35) *
No, there is no such box. Does its existence depend on some browser plug in or having Active-X enabled?
I'm well familiar with the general procedure for making attachments. There just isn't any such option that I have ever been able to find on this particular forum.

Amen. I tried IE7, Firefox, Opera. Never saw a box labeled 'Attachment' or similar. Maybe someone could attach a screen shot of the attachment-box......

Woody
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cliveb
post May 12 2007, 10:41
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QUOTE (woody_woodward @ May 11 2007, 21:50) *
QUOTE (AndyH-ha @ May 11 2007, 11:35) *

No, there is no such box. Does its existence depend on some browser plug in or having Active-X enabled?
I'm well familiar with the general procedure for making attachments. There just isn't any such option that I have ever been able to find on this particular forum.

Amen. I tried IE7, Firefox, Opera. Never saw a box labeled 'Attachment' or similar. Maybe someone could attach a screen shot of the attachment-box......

Here's a screen shot of what happens for me. It shows the "File Attachments" box after having uploaded one file (mozart.flac).
Attached Image

I'm using Firefox 1.5.0.11. I have no idea if ActiveXs are in use: I can't find anything about ActiveXs in Firefox's Options dialog, nor are they mentioned in the program help. Javascript is enabled, if that's relevant.

I also checked with IE 6. That also showed the "File Attachments" box, even when I replied NO to "do you want to allow ActiveX to run" question.

Had a quick look around my user settings to see if there were any referring to whether attachments can be uploaded, but didn't find anything. There's a "manage your attachments" section, but that just allows you to delete ones that have previously been uploaded.

Note that you don't get the "File Attachments" box if you use "Fast Reply".
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charliemcdo
post May 12 2007, 18:02
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Sorry to be off topic here, but I just wanted to add that when I post a reply, I also don't get the section for file attachments. I see the Post Options section and directly below the Post Icons section, with no Attachment section in between.
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AndyH-ha
post May 12 2007, 19:19
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Obviously, the file attachment section is a privilege extended only to those who know the secret handshake.

We will see a report on the Foobar2000-mono file experiment, won't we?
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cliveb
post May 12 2007, 22:51
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QUOTE (AndyH-ha @ May 12 2007, 19:19) *
Obviously, the file attachment section is a privilege extended only to those who know the secret handshake.

I always knew joining the masons would pay off in the end....

OK, the only thing that I see which is different about us is that I'm in the "Developers" group, rather than "Members". Could that be relevant? (I never asked to be in that group - it just happened one day, presumably a decision of one of the admins).

Maybe a posting in the "Site Related Discussion" group might elicit an answer?
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AndyH-ha
post May 13 2007, 05:20
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And do you perchance remember a late night visit from a small creature, who spoke in a human tongue, shortly before this change occurred?
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2Bdecided
post May 14 2007, 09:55
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I bet it's something to do with developers or members or something.

However, I think that all users, even those without the secret handshake, can start a new thread of their own in the uploads forum (just click forums, uploads), and attach files.

"Developers" can do this in any forum, not just uploads.

Cheers,
David.
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2Bdecided
post May 14 2007, 10:34
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QUOTE (cliveb @ May 11 2007, 09:51) *
QUOTE (2Bdecided @ May 10 2007, 10:36) *
If you can test a real recording in foobar2k, or upload a 30 second extract of a mono restoration, just before the final mixdown to mono, so I can test it myself, that would be great.

OK, I fished around in the attic and did find a few mono records, so I've recorded a short section from one for you to play with. (If you're interested, it's an extract from Mozart's Flute Concerto No 2. Recording was made in 1958). Bear in mind that this is a straight recording - I haven't done any declicking/denoising at all. My understanding is that your goal is to compare the effect on background noise of a straight mixdown to mono against Foobar's "keep centre channel" plugin, so I'd have thought the fact that this hasn't been declicked shouldn't affect the outcome of that. I deliberately picked a quiet section so that the surface noise is very obvious.

Attached File  mozart.flac ( 1.26MB ) Number of downloads: 183



Thanks Clive, that's perfect. That background noise is just the kind of thing I was hoping to test.

Unfortunately, my testing was more complicated than I expected! (Though the results are encouraging).

Firstly, I'd already spotted that there's some kind of bug/feature/issue which reduces the amount of treble in the "keep centre" output of this plug-in. Therefore, for a "fair" test, I had to EQ the result to make it sound more like the original. I've also provided the output before my EQing.

Secondly, though there is distinctive background noise in this extract, there are also some clicks. These can be distracting when comparing, so I've also done a version with the clicks removed. I used Cool Edit Pro's Click/Pop/Crackle Eliminator with the "Old Record - Quiet Audio" pre-set. I didn't tweak it at all (I didn't even autofind all levels) so it's not a good declicking job - just for testing.


So, here are the results. You don't need to download all these files - I've just included them all for reference.

Attached File  1_Flute_Concerto_2_original_mono.flac ( 757.87K ) Number of downloads: 181
1 is Clive's original, converted to mono by summing the channels.

Attached File  2_Flute_Concerto_2_original_centre_cut.flac ( 686.01K ) Number of downloads: 176
2 is Clive's original, converted to mono using the Centre Cut plug-in

Attached File  3_Flute_Concerto_2_original_centre_cut_EQ.flac ( 750.42K ) Number of downloads: 174
3 is file 2 (Centre Cut) EQ'd by me


Attached File  4_Flute_Concerto_2_declick.flac ( 1.33MB ) Number of downloads: 180
4 is Clive's original, declicked by me

Attached File  5_Flute_Concerto_2_declick_mono.flac ( 754.56K ) Number of downloads: 175
5 is file 4 (declicked), converted to mono by summing the channels.

Attached File  6_Flute_Concerto_2_declick_centre_cut.flac ( 681.18K ) Number of downloads: 176
6 is file 4 (declicked), converted to mono using the Centre Cut plug-in

Attached File  7_Flute_Concerto_2_declick_centre_cut_EQ.flac ( 745.48K ) Number of downloads: 178
7 is file 6 (declicked, Cenre Cut), EQ'd by me


Comparing file 3 with file 1, I find the remaining clicks too distracting to judge easily.

Comparing file 7 with file 5, I think the Centre Cut version has somewhat lower background noise, no appreciable artefacts from the Centre Cut processing, other than the EQ which I'm not sure I've corrected completely.


To me, this seems like a useful tool which I will add to my list of processes which I might choose to use, or at least try, depending on circumstances.

Hope this is of interest.


EDIT: what I didn't include, though it's easy enough to try, is just keeping the channel with the lowest noise from the two stereo channels. In this case, it's not as good as Centre Cut mono.

Cheers,
David.

This post has been edited by 2Bdecided: May 14 2007, 11:56
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2Bdecided
post May 14 2007, 11:35
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QUOTE (AndyH-ha @ May 11 2007, 05:44) *
I have a segment of that recording, declicked, that doesn't seem too bad. However, it is in 32 bit floating point, my normal working format, and the size is 11meg+, an all day upload via this dial-up connection. It would be easier if resampled to 16 bit, but still pretty large. An mp3 version would obviously be easier yet. I need to know what you think you need to work with.


Hi Andy,

I'd be interested to try, but I can imagine anything will be painful for you to upload via dial-up.

I'd be happy with 44.1kHz 16-bit stereo, FLAC or similar (i.e. lossless, not lossy mp3).

30 seconds maximum, and less is fine to make file sizes manageable for you. Even ten seconds can be useful if chosen carefully.

The results I have just posted may make it more or less likely that you want to try this.

Cheers,
David.
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cliveb
post May 14 2007, 12:30
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QUOTE (2Bdecided @ May 14 2007, 10:34) *
Secondly, though there is distinctive background noise in this extract, there are also some clicks. These can be distracting when comparing, so I've also done a version with the clicks removed.

Yes, sorry about that - I just found a convenient mono record (this was an old 10" Decca ffss one) and recorded it for you. I didn't even bother to clean it first, because I thought that might maximise the surface noise for the purposes of your experiment.

QUOTE (2Bdecided @ May 14 2007, 10:34) *
Comparing file 7 with file 5, I think the Centre Cut version has somewhat lower background noise, no appreciable artefacts from the Centre Cut processing, other than the EQ which I'm not sure I've corrected completely.

Yes, interesting results - so much so that I decided to download the FB2K centercut plugin to have a play about. But after I installed it, I get an error message on starting up FB2K ("unable to load foo_dsp_centercut.dll"). Another mesaage said that "shared.dll" was not found. I presume that foo_dsp_centercut uses this other DLL. Any idea what that DLL is? (I'm running FB2K v0.8.3, on WinXP Pro SP2).
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2Bdecided
post May 14 2007, 13:21
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Hi Clive,

I wasn't criticising or complaining - I'm very grateful for the file. I was just explaining why I felt the need to declick it.

I believe this plug-in works with foobar2k version 0.9.something, not 0.8, hence your problems. 0.8 and 0.9 are incompatible.

If you like v0.8.3 a lot be careful about replacing it. I used 0.8.3 a lot, and 0.9 is quite different. Still great, but read the update threads, especially the "why are you still using 0.8?" thread!

I assume you can install 0.9 in a separate folder and keep 0.8.3, but I have not tried this myself.

Hope this helps.

Cheers,
David.
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cliveb
post May 14 2007, 14:50
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QUOTE (2Bdecided @ May 14 2007, 13:21) *
I wasn't criticising or complaining - I'm very grateful for the file. I was just explaining why I felt the need to declick it.

No sweat - I didn't think you were complaining. I just felt a little guilty at supplying a file that you had to fiddle with before you could use it.

QUOTE (2Bdecided @ May 14 2007, 13:21) *
I believe this plug-in works with foobar2k version 0.9.something, not 0.8, hence your problems. 0.8 and 0.9 are incompatible.

If you like v0.8.3 a lot be careful about replacing it. I used 0.8.3 a lot, and 0.9 is quite different. Still great, but read the update threads, especially the "why are you still using 0.8?" thread!

OK, thanks for the info. I did once try out v0.9, but decided to go back to 0.8.3 - it does exactly what I need of it, and I couldn't really face the effort of switching, since I'm a fairly infrequent FB2K user. It's only used for masstagging, transcoding and ReplayGaining - all my actual listening is done with Slim Devices stuff.
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AndyH-ha
post May 15 2007, 08:43
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The file, resampled to 16 bit, is at
http://www.hydrogenaudio.org/forums/index....showtopic=54879

There are three low frequency thumps. They were not associated with clicks. Everything seems fine to me when I run a 3rd order Butterworth filter, cutoff 120Hz, in their vicinity, but I left them in for your test.
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2Bdecided
post May 18 2007, 10:04
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QUOTE (AndyH-ha @ May 15 2007, 08:43) *
The file, resampled to 16 bit, is at
http://www.hydrogenaudio.org/forums/index....showtopic=54879

There are three low frequency thumps. They were not associated with clicks. Everything seems fine to me when I run a 3rd order Butterworth filter, cutoff 120Hz, in their vicinity, but I left them in for your test.


Hi Andy,

I can't hear any background noise in your file, whether listening in stereo, standard mono, or "centre-cut:centre" mono. I've uploaded the latter. I haven't corrected the EQ problem this time, so it sounds duller than the original.

When I did a sum/difference in your original file, I saw that the noise in the "difference" channel was very low, and consisted mainly of the remnants of clicks. These were inaudible to me under normal listening.


I was hoping to get the chance to listen to your file under quieter conditions, but haven't had the chance, so can only report that I can't hear any noise in the file when listening with the PC on.

Cheers,
David.
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Attached File  seg_16_centre_cut.flac ( 1.11MB ) Number of downloads: 78
 
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AndyH-ha
post May 20 2007, 00:42
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Do you want something from another album to play with (a quiet piano solo)?
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