Quantcast Audio issues during VHS transfer? - digitalFAQ Forum
  #1  
03-23-2019, 03:30 AM
KingBuZZo KingBuZZo is offline
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I'm currently transferring a bunch of VHS master cassettes of concert recordings from the mid 80s to the early 90s, most of these tapes feature two or three indivual concerts. My workflow: JVC HR-S9600EU > Datavideo TBC-1000 > ATI TV Wonder 600 USB.

Now apparently I'm only able to capture the "Norm" audio track and not the HiFi one for the majority of the recordings (but not all of them either! - there's even one tape with two different recordings, the first one I only get the Norm audio, the second one I get the HiFi track. With commercial VHS tapes, I have no issues getting the HiFi track played back).

Didn't think about it much initially, I assumed maybe the 80s VHS camcorder didn't record HiFi audio at all (which is probably bullshit?), additionally I don't know whether all these recordings were made using the same camcorder.

Recently though I stumbled upon a tape which featured a partial copy of a concert recording I already transferred from the VHS master cassette, and to my surprise, it had HiFi audio throughout (with a few "dropouts" to "Norm" audio), while my master transfer only features the Norm audio track. It's likely that this copy was made not much later after being recorded.

So I'm wondering what's going on and what to do... maybe you have some advice for me?

Some ideas:
1) I'm gonna try out those tapes on a few different VCRs, check whether the HiFi track plays fine on those decks. I have access to at least two, maybe three different VCRs, not necessarily high-end, but will be good enough for testing.
2) If it turns out that the HiFi track is indeed accessible on any of these other VCRs, I should probably have my VCR serviced (or the heads cleaned for a start). I bought it two years ago and the seller claimed to have serviced the machine, but this could be bogus.
3) Otherwise, could it be that the tapes have deteriorated over the years, basically destroying the HiFi audio track (as I mentioned, it's not all of them though)? On the other hand, I'm barely having any issues with the video content.

Thankful for any input! I wanna get those tapes properly archived and if it is somehow possible to get the better audio tracks, I need to find a way.
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  #2  
03-23-2019, 10:41 AM
Tester Tester is offline
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These HR-S9600EU units (and other JVC models as well) can be picky for Hi-Fi playback, especially for tapes recorded in different (domestic) machines/brands — I've found they tend to fall back to linear audio sooner than other VCRs/makes. This, even when they were new.

On most cases, you can make do by assembling two playback passes: one with tracking maximized for best video (usually with ‘norm’ audio) and other with tracking adjusted for Hi-Fi (usually yielding poorer video).

But more than once I have come across tapes where these JVCs didn't acknowledge the Hi-Fi audio at all, no matter how much you tried (mis)adjusting tracking, as if those tapes weren't recorded in Hi-Fi... only to find, again, that other deck would play them in Hi-Fi without much trouble.

This is another of those scenarios/reasons where/why it pays to have different VCR(s) for troublesome tapes, as Lordsmurf always says.

Last edited by Tester; 03-23-2019 at 10:54 AM.
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  #3  
03-23-2019, 11:36 AM
KingBuZZo KingBuZZo is offline
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Just tried out some tapes on a Panasonic NV-FJ 616 (seems kinda crappy, but it is all I have access to right now), and it showed exactly the same behavior like my JVC machine re. picking the audio track...
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03-23-2019, 11:51 AM
hodgey hodgey is offline
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Maybe you did already, it can be helpful to adjust the tracking manually for Hi-Fi, the auto-tracking function doesn't always find the perfect spot for picking up the hi-fi audio.
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  #5  
03-23-2019, 01:23 PM
dpalomaki dpalomaki is offline
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Trying different VCRs is a good idea.

Quote:
I assumed maybe the 80s VHS camcorder didn't record HiFi audio at all (which is probably bullshit?), additionally I don't know whether all these recordings were made using the same camcorder.
Only some VHS camcorders and VCRs would record Hi-Fi tracks while all would record a linear (normal) audio. Thus if your tapes and/or parts of tapes were recorded in different camcorders/VCRs that could account for the lack/presence of a Hi-Fi track. Consistent behavior across several different makes/models of VCR can confirm this.
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03-24-2019, 07:10 AM
KingBuZZo KingBuZZo is offline
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Okay there's another recording, the master VHS only gives me linear audio regardless of any manual tracking manipulation. But then there's a dub of the same recording on another tape and it flawlessly plays the HiFi track.

My theory is the following:
The original camcorder had a certain way of writing the HiFi track onto the tape. My JVC VCR cannot read it at all for some reason. When the dub was made, my guess is that the tape was played back on the original camcorder used for taping (thus properly picking up the HiFi aufio) , and that one was connected to a VCR which produced the copy. My VCR is able to read the HiFi track written by the VCR used for copying.
In conclusion, that's why the HiFi track only plays on dubs for me and not on the masters themselves.

Does that make any sense?

Next steps: Try to jog the taper's memory, maybe he remembers the brand of the camcorder. In theory, the probability that a VCR of the same brand is able to play back the HiFi track is probably the highest. Now I have to hope that it is something like Sony and not an oddball manufacturer.
I guess getting my JVC VCR serviced won't change anything in this regard.
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03-24-2019, 09:18 AM
hodgey hodgey is offline
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Maybe a stupid question, but have you checked if the hi-fi audio on the dub is originally from a Hi-Fi track, or just a copy of the linear audio on the master?
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03-24-2019, 09:27 AM
KingBuZZo KingBuZZo is offline
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Yes of course, it sounds considerably better and reaches a wider frequency range on the dubs. No doubt this is the real HiFi audio track.
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  #9  
03-24-2019, 09:53 AM
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Are routing audio around the TBC-1000? (It's the VP299 internal distribution amp inside.)
Or did you connect audio to the TBC-1000?

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03-24-2019, 10:01 AM
hodgey hodgey is offline
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I know VHS-C camcorders have a smaller drum and different tape path setup compared with full-size VHS decks. If you can't get it to work in a different brand of VCR, maybe a VHS-camcorder with Hi-Fi may work. Granted, others here probably have more experience with that than me, Hi-FI was quite rare on VHS-C camcoders.
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03-24-2019, 10:43 AM
dpalomaki dpalomaki is offline
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Just a thought or two:

Was the master tape recorded in stereo? While linear stereo was offered on early VHS, Hi-Fi did not appear until around 1984 or so. And through the 1980s into the 1990s the Hi-Fi capable camcorders were mainly high end S-VHS and Hi8 models.

The Hi-Fi audio and video heads are on the same cylinder and their relative tracking is locked. If the playback unit mistracks the video it will generally mistrack the audio. The main issue is the Hi-Fi AFM signal recorded on the tape might be weak. If several different Hi-Fi VCRs cannot read it, it likely is not there.

If the master was linear track audio only (and perhaps mono to boot): The copy very likely recorded the the master's linear track audio to both the linear and Hi-Fi track because the VCR used to make the copy was Hi-Fi. It could be stereo if the original linear track was stereo and the playback VCR has a stereo linear track.

The copy's Hi-Fi track will sound better than its linear track because it has minimal generation loss in the copy process, while the linear track has significant generation loss, including an increase in the noise floor and limited frequency response (typically 100-10,000 Hz for SP speed, compared to 20-20K for the Hi-Fi track). Also, the copy Hi-Fi track may sound better than the master linear track if the playback VCR's linear head's azimuth does not match that of the master tape

The high frequency loss is a combination of the limited bandwidth of the linear track coupled with sensitivity of linear track to precise linear head alignment. Even slight misalignment of linear head azimuth can result in high frequency losses. Unless the system has Dolby or similar audio noise reduction, the linear track peak signal to noise ratio is probably around -40 dB and will degrade by perhaps 3 to 6 dB on the copy.
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  #12  
03-24-2019, 12:50 PM
KingBuZZo KingBuZZo is offline
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Quote:
Originally Posted by lordsmurf View Post
Are routing audio around the TBC-1000? (It's the VP299 internal distribution amp inside.)
Or did you connect audio to the TBC-1000?
I'm routing the audio around the TBC. I was told there's no need to passthrough the audio.

Quote:
Originally Posted by hodgey View Post
I know VHS-C camcorders have a smaller drum and different tape path setup compared with full-size VHS decks. If you can't get it to work in a different brand of VCR, maybe a VHS-camcorder with Hi-Fi may work. Granted, others here probably have more experience with that than me, Hi-FI was quite rare on VHS-C camcoders.
These are full size regular VHS tapes though, no VHS-C.

Quote:
Originally Posted by dpalomaki View Post
Just a thought or two:

Was the master tape recorded in stereo? While linear stereo was offered on early VHS, Hi-Fi did not appear until around 1984 or so. And through the 1980s into the 1990s the Hi-Fi capable camcorders were mainly high end S-VHS and Hi8 models.
Yes the master tapes seem to be in HiFi stereo. I mean if they weren't, where does the noticeably better audio on the first gen come from then? I will post samples tomorrow, you'll agree with me I'm sure

Quote:

The Hi-Fi audio and video heads are on the same cylinder and their relative tracking is locked. If the playback unit mistracks the video it will generally mistrack the audio. The main issue is the Hi-Fi AFM signal recorded on the tape might be weak. If several different Hi-Fi VCRs cannot read it, it likely is not there.
No video tracking issues that are worth mentioning.
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  #13  
03-24-2019, 12:57 PM
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Quote:
Originally Posted by KingBuZZo View Post
the seller claimed to have serviced the machine, but this could be bogus.
Very likely. I recently bought something that was "tested" and "found to be working as it should:. But when it got here, the electrical pins were bent. So how exactly was it tested?

Quote:
I'm routing the audio around the TBC. I was told there's no need to passthrough the audio.
Correct. Route around. Just verifying.

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03-25-2019, 08:20 AM
KingBuZZo KingBuZZo is offline
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Here's a short sample clip, both from master and first gen. The master transfer has linear audio only, the first gen transfer picked up the HiFi audio track, which sounds considerably better.


Attached Files
File Type: avi master.avi (85.36 MB, 3 downloads)
File Type: avi firstGen.avi (78.94 MB, 6 downloads)
File Type: wav master.wav (2.13 MB, 2 downloads)
File Type: wav firstGen.wav (2.13 MB, 2 downloads)
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  #15  
03-25-2019, 10:37 AM
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(I don't think that's the case here, but) it is always possible that the Hi-Fi audio on the ‘1st-gen copy’ comes from a separate audio source.
These gigs were often taped simultaneously with a Camcorder and an audio field recorder, for better sonics, then assembled for the VHS copy.

Last edited by Tester; 03-25-2019 at 11:14 AM. Reason: Clarification
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03-25-2019, 11:00 AM
dpalomaki dpalomaki is offline
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A few observations. I opened the audio files in Adobe Audition to examine the waveforms. I amplified both signals in Audition by 10 dB to give a better display. Waveforms are shown in the attached PDF file.
My conclusions are:

Both files monophonic (left and right channel essentially identical). There is no significant phase or amplitude differences between the channels in either file that would be characteristic of a stereo signal, even if a single point stereo mic was used.

The First Gen file is about 3 dB louder than the master in terms of average and total RMS power. But the Maximum RMS power is less than 1 dB higher. Looking at the waveforms, the master shows a larger dynamics (greater differences between peak and non-peak sounds). The First Gen's peaks at drum beat were squashed. This implies that the First Gen was subject to automatic level control (audio AGC) in the recording process, typical of VCRs. The 3 dB higher average record level can make it subjectively sound better. (We don't know whether or not in the process of making the First Gen they did any sound sweetening.)

Examining the frequency spectrum (ignoring the odd blip in the master at ~270 Hz), the high frequency roll-off is about the same to 10 kHz. A bit beyond 10 kHz both show the levels shelving rather than a gradual roll-off. The First Gen shows a blip at the horizontal frequency, and what is probably the noise floor of the playback system used making the FirstGen recording.

For an illustration of what to expect from a linear and a Hi-Fi track, I captured a bit of the linear track and the stereo Hi-Fi track from the Disney Fantasia tape, the fanfare at the tape start. The linear track shows the expected sharp drop above 10 kHz and then rises to a noise floor. The Hi-Fi track shows a gradual roll off 20 kHz (no shelf).

All that said, a poor master recording could have created the single channel audio and the high frequency roll-off and shelving seen in the First Gen copy, but the crushed dynamic range is something else to consider.

It boils down to which audio pleases you the most.


Attached Files
File Type: pdf AudioViews.pdf (383.1 KB, 1 downloads)

Last edited by dpalomaki; 03-25-2019 at 11:26 AM.
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  #17  
03-25-2019, 12:40 PM
KingBuZZo KingBuZZo is offline
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Quote:
Originally Posted by Tester View Post
(I don't think that's the case here, but) it is always possible that the Hi-Fi audio on the ‘1st-gen copy’ comes from a separate audio source.
These gigs were often taped simultaneously with a Camcorder and an audio field recorder, for better sonics, then assembled for the VHS copy.
I'm sure the taper would've told me if he did so. That's not the case here I'm quite certain.

Quote:
Originally Posted by dpalomaki View Post
A few observations. I opened the audio files in Adobe Audition to examine the waveforms. I amplified both signals in Audition by 10 dB to give a better display. Waveforms are shown in the attached PDF file.
My conclusions are:

Both files monophonic (left and right channel essentially identical). There is no significant phase or amplitude differences between the channels in either file that would be characteristic of a stereo signal, even if a single point stereo mic was used.

The First Gen file is about 3 dB louder than the master in terms of average and total RMS power. But the Maximum RMS power is less than 1 dB higher. Looking at the waveforms, the master shows a larger dynamics (greater differences between peak and non-peak sounds). The First Gen's peaks at drum beat were squashed. This implies that the First Gen was subject to automatic level control (audio AGC) in the recording process, typical of VCRs. The 3 dB higher average record level can make it subjectively sound better. (We don't know whether or not in the process of making the First Gen they did any sound sweetening.)

Examining the frequency spectrum (ignoring the odd blip in the master at ~270 Hz), the high frequency roll-off is about the same to 10 kHz. A bit beyond 10 kHz both show the levels shelving rather than a gradual roll-off. The First Gen shows a blip at the horizontal frequency, and what is probably the noise floor of the playback system used making the FirstGen recording.

For an illustration of what to expect from a linear and a Hi-Fi track, I captured a bit of the linear track and the stereo Hi-Fi track from the Disney Fantasia tape, the fanfare at the tape start. The linear track shows the expected sharp drop above 10 kHz and then rises to a noise floor. The Hi-Fi track shows a gradual roll off 20 kHz (no shelf).

All that said, a poor master recording could have created the single channel audio and the high frequency roll-off and shelving seen in the First Gen copy, but the crushed dynamic range is something else to consider.

It boils down to which audio pleases you the most.
I think there was indeed just a mono microphone used.

I've attached the spectral view for each whole clip, and there's definitely content on the first gen that is not on the master.


Attached Images
File Type: jpg firstGen.jpg (55.8 KB, 8 downloads)
File Type: jpg master.jpg (47.9 KB, 5 downloads)

Last edited by KingBuZZo; 03-25-2019 at 01:10 PM.
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03-25-2019, 01:10 PM
KingBuZZo KingBuZZo is offline
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Here's a more obvious example.
Line audio should only be able to store up to 10kHz audio information, and there's a lot more on the first gen.


Attached Files
File Type: wav MW_master.wav (10.60 MB, 3 downloads)
File Type: wav MW_firstgen.wav (10.60 MB, 2 downloads)
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  #19  
03-25-2019, 03:42 PM
dpalomaki dpalomaki is offline
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It goes back to trying additional HiFi VCRs (not the same JVC) to verify content.

And use the sound you like.

Any idea what the mic was? Or was it a board feed to the recorder?
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03-25-2019, 03:51 PM
KingBuZZo KingBuZZo is offline
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Quote:
Originally Posted by dpalomaki View Post
It goes back to trying additional HiFi VCRs (not the same JVC) to verify content.

And use the sound you like.

Any idea what the mic was? Or was it a board feed to the recorder?
Yep, seems like the only way.

Of course I'd prefer the HiFi audio! Vastly superior.

I believe the camera's built-in mic was used...
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