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CX reduction and audio capture
https://forum.lddb.com/viewtopic.php?f=12&t=11202
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Author:  lucas2001 [ 01 Feb 2024, 18:33 ]
Post subject:  CX reduction and audio capture

Hello everyone, my name is Lucas. And just let me go straight into my confusion.

I am a newbie to laserdisc world. And currently I have a Pioneer CLD-HF9G. I am dedicated in collecting vhs before, but after I listen to some die-hard archievers who upload lots of laserdisc video onto youtube, I sinply fall in love with that interesting digital and analog audio track. Also the picture quality is far beyond vhs as well.

Well, my problem is, I have some karaoke laserdiscs, I want to capture them through OBS by using gvusb2.0. But after I captured, the analog vocal seems noisy background, unpleasent bass and high. Is that a problem regarding the cx reduction? Most of the player should manually turn that thing on by remote?

*Player itself is in excellent condition, it has been refurbished and should not have critical relation to my problem.

Author:  ldfan [ 01 Feb 2024, 20:41 ]
Post subject:  Re: cx reduction

I assume this is a Karaoke disc that utilizes the multiplex feature where the the left channel should have the background music only and the right has the background + vocals?

If so, in most cases I think CX is turned off (but I could be wrong) but it shouldn't sound any different than what is on the digital tracks (which are usually background music only). How does the analog track sound connected directly to your amp or TV speakers?

Author:  signofzeta [ 01 Feb 2024, 22:01 ]
Post subject:  Re: cx reduction

IIRC CX requires stereo, doesn’t work in mono.

There is no way to turn CX off with that player so that’s not the issue.

The issue CX was developed to solve only affects one channel so if it’s murked equally then its not that noise.

Regardless, I’d question the setup first. Maybe the gain is just too high or maybe the recording just sucks. If you don’t have a mixer or anything to monitor the sound live these kinds of things are unsolvable.

Author:  lucas2001 [ 02 Feb 2024, 01:53 ]
Post subject:  Re: cx reduction

ldfan wrote:
I assume this is a Karaoke disc that utilizes the multiplex feature where the the left channel should have the background music only and the right has the background + vocals?

If so, in most cases I think CX is turned off (but I could be wrong) but it shouldn't sound any different than what is on the digital tracks (which are usually background music only). How does the analog track sound connected directly to your amp or TV speakers?


Thanks for your words, so far I just capture it into my laptop and I have not yet use my tv for testing. It can be the problem of mono track of that analog vocal, leads to cx reduction not activated. Or as you said, there should be a button on the remote to turn on cx.

Author:  lucas2001 [ 02 Feb 2024, 02:00 ]
Post subject:  Re: cx reduction

signofzeta wrote:
IIRC CX requires stereo, doesn’t work in mono.

There is no way to turn CX off with that player so that’s not the issue.

The issue CX was developed to solve only affects one channel so if it’s murked equally then its not that noise.

Regardless, I’d question the setup first. Maybe the gain is just too high or maybe the recording just sucks. If you don’t have a mixer or anything to monitor the sound live these kinds of things are unsolvable.


I use gvusb for capture the both video and sound. I can monitor it through OBS. The db level is really low and I need to increase around 7 db(nearly 230% volume) in the software for clear and louder sound monitor. That may not be a correct way to handle. I believe the sound is exactly what you said, the analog vocal is being recorded in mono.

Is there any ideal way to solve this problem? Any good capture device you recommended?

Author:  lucas2001 [ 02 Feb 2024, 02:08 ]
Post subject:  Re: cx reduction

ldfan wrote:
I assume this is a Karaoke disc that utilizes the multiplex feature where the the left channel should have the background music only and the right has the background + vocals?

If so, in most cases I think CX is turned off (but I could be wrong) but it shouldn't sound any different than what is on the digital tracks (which are usually background music only). How does the analog track sound connected directly to your amp or TV speakers?


That's correct. This karaoke disc audio mode is designed in analog and digital. Digital/Analog stereo, 1 channel Left/ Right. In detailed, I can press the audio mode for 6 times. That covers all audio mode avaliable on this disc. Maybe I should capture it in mono mode, and the player still set in analog stereo, the problem will be solved.

Author:  signofzeta [ 02 Feb 2024, 13:01 ]
Post subject:  Re: cx reduction

lucas2001 wrote:
signofzeta wrote:
IIRC CX requires stereo, doesn’t work in mono.

There is no way to turn CX off with that player so that’s not the issue.

The issue CX was developed to solve only affects one channel so if it’s murked equally then its not that noise.

Regardless, I’d question the setup first. Maybe the gain is just too high or maybe the recording just sucks. If you don’t have a mixer or anything to monitor the sound live these kinds of things are unsolvable.


I use gvusb for capture the both video and sound. I can monitor it through OBS. The db level is really low and I need to increase around 7 db(nearly 230% volume) in the software for clear and louder sound monitor. That may not be a correct way to handle. I believe the sound is exactly what you said, the analog vocal is being recorded in mono.

Is there any ideal way to solve this problem? Any good capture device you recommended?


The very first thing you need to do is listen to the player on its own to see if that’s the problem. Hook it to a stereo or some headphones or something. Remove the capture system completely from the equation. This is Diagnosis 101. Isolate the issue, don’t add to it.

If the level is quiet coming from the player then there is an issue with the player or the disc. Put in another disc, if that’s bad too then it’s the player.

This is not a CX related issue in any way but I’ll explain this regardless. There is no way to turn CX off on this player. You read that right. If the disc can use CX then the player turns it on automatically and you can’t turn it off. It’s essentially always on unless you have a non-CX disc without the auto flag in which case you can manually turn it on. If your disc doesn’t say “CX On” or whatever then it doesn’t work with that disc. Like I said thought, this is not a CX issue. CX doesn’t turn garbage audio into gold it just removes some interference from the video, mostly.


Are you recording from the LD players digital or analog outputs?

Author:  remav [ 08 Feb 2024, 07:29 ]
Post subject:  Re: CX reduction and audio capture

...also, Karaoke discs can have different capabilities on different discs. Make sure you understand that you can get both the digital and the analog tracks to come out the analog outputs.
I can't explain what you're experiencing, however.

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