Last Active: Mar 30, 2022
Threads: 46
Posts: 910
Reputation:
16
Null test is used to check if two audio channels are identical.
In this example I will compare the two channels (left and right) of a FLAC file, obtained from the ripping of a CD.
First we open the FLAC with Audacity:
![[Image: RxaMU9J.png]](http://i.imgur.com/RxaMU9J.png)
Then we split the channels; going to the name of the track (1 in red), we select "Split stereo to mono". Now we have two independent mono channels instead of left and right, the sound has not been modified.
![[Image: t1nDQSp.png]](http://i.imgur.com/t1nDQSp.png)
Now we select one track clicking on it, and go to effect (2 in red) and invert.
![[Image: tw4oqof.png]](http://i.imgur.com/tw4oqof.png)
Now we select both, pressing Alt and clicking both:
![[Image: Mdq6zR7.png]](http://i.imgur.com/Mdq6zR7.png)
Now we go to tracks (3 in red) and select "mix and render":
![[Image: j0a2l0r.png]](http://i.imgur.com/j0a2l0r.png)
This channel is null (no sound), this means that left and right channels were identical (real mono).
Some CDs, even based on monoaural recordings, are not real mono, because during remastering differences are introduced between the channels, this is called near-mono. The resulting track from the null test is like this:
![[Image: 5fdIFi5.png]](http://i.imgur.com/5fdIFi5.png)
If the recording is in stereo, the resulting track is clearly non null:
![[Image: E0L7z2W.png]](http://i.imgur.com/E0L7z2W.png)
Last Active: May 09, 2014
Threads: 11
Posts: 260
Reputation:
11
Interesting thread. I never knew there were different types of mono recordings. Is it done on purpose or are "near mono" recordings a result of someone's lack of skill. Why would you want to compare channels? Are there recordings that claim "mono" but are actually "near mono"?
Last Active: Mar 30, 2022
Threads: 46
Posts: 910
Reputation:
16
Hi.
There's a thread about mono rips that I started back in the day. This tutorial is meant to be used there. I'm planning to post some examples. The issue is that if the CD is not real mono the rip is not proper lossless if you rip in mono, because the CD source is modified, although the sound is not degraded. Most of the classical music mono CDs are real mono, but some are not.
Last Active: May 09, 2014
Threads: 11
Posts: 260
Reputation:
11
Last Active: Sep 13, 2024
Threads: 18
Posts: 684
Reputation:
4
sorry for going slightly offtopic, but are you still on about "we want single channel lossless" again ? 
Last Active: Mar 30, 2022
Threads: 46
Posts: 910
Reputation:
16
Not at all. Why no one rips in mono? Because there's no point in doing so.
If the channels are identical (real mono), the size is identical ripping in mono or stereo. If the channels are different, you gain some file size, but you are modifying the file source (CD), so it's not a lossless rip. The sound is not degraded, but it's not an improvement neither.
I read that there are no real mono CDs, that's not true neither; in fact, in classical music most are. My intention is just try to clarify some concepts. The examples are just for educational purposes, this is a rare subject, when I said that I have never found a mono flac it's completely true. Of course I didn't find any because it's just plain stupid ripping in mono.
Reading that thread is quite embarrasing but if something can be learnt it won't be a complete waste.
Last Active: Apr 13, 2015
Threads: 62
Posts: 2,121
Reputation:
5
So...you've created this thread to show us why nobody should do what nobody is doing?
Last Active: Sep 13, 2024
Threads: 18
Posts: 684
Reputation:
4
Well I have to agree. Even today, where harddrives are fairly cheap , I still try to optimise filesizes on some stuff.
Last Active: May 09, 2014
Threads: 11
Posts: 260
Reputation:
11
(Apr 23, 2014, 16:09 pm)connor17 Wrote: Not at all. Why no one rips in mono? Because there's no point in doing so.
If the channels are identical (real mono), the size is identical ripping in mono or stereo. If the channels are different, you gain some file size, but you are modifying the file source (CD), so it's not a lossless rip. The sound is not degraded, but it's not an improvement neither.
I read that there are no real mono CDs, that's not true neither; in fact, in classical music most are. My intention is just try to clarify some concepts. The examples are just for educational purposes, this is a rare subject, when I said that I have never found a mono flac it's completely true. Of course I didn't find any because it's just plain stupid ripping in mono.
Reading that thread is quite embarrasing but if something can be learnt it won't be a complete waste.
I'm away from my PC and dBpoweramp at the moment but I'm assuming you can rip a cd to FLAC in mono. I do have many cds/vinyl in mono (Jazz, Classical, the 2009 Remastered Mono Beatles Box Set) or at least "claim" they are mono. I've never ripped any of them to my HD. Would the best way to do it be configuring dBpoweramp to mono recording? If I'm understanding you correctly, there's no benefit to ripping a mono recording in "stereo" except the downside of creating a larger file size then necessary if the original wasn't "true mono".
This stuff interests me so thanks again for the thread..... 
Last Active: Mar 30, 2022
Threads: 46
Posts: 910
Reputation:
16
(Apr 24, 2014, 13:00 pm)tuffgong Wrote: Would the best way to do it be configuring dBpoweramp to mono recording? If I'm understanding you correctly, there's no benefit to ripping a mono recording in "stereo" except the downside of creating a larger file size then necessary if the original wasn't "true mono". No. It's the opposite. It's better to rip in stereo always. If you rip in mono, there are two possibilities:
1. The CD is real mono. The rip will be identical in size to the stereo rip. You don't gain anything.
2. The Cd is near mono. You will gain some file size, but the rip won't be lossless (you couldn't burn to the original CD). The sound is not degraded, but the sound alone is not the only thing many people look at.
|
