Video tape

[fastcat]

I was trying out DC 7.5 live and had my camcorder connected to the PC, I decided to use the sound track from the video. Using the ez forensic filters I find there appears to be another sound track which has nothing to do with the pictures. I have tried to enhance the voices but they get so high they become unclear. Could anyone tell me which filters I need to lower the voice and keep the speed constant. Looking forward to your help.
Peter

[Craig Maier]

Hi,

If by high, you mean the pitch has changed, then I think that the "Stretch and Squish" effect is designed to do what you want to do. However, you may want to run a bandpass filter on the material first so that you are only working with the in-band signals of true interest. But high could also mean loud and I need clarification as to what you really mean by "high".

Craig

[Dan McDonald]

or if it's just an older recording that didn't completely erase, it was probably recorded at a different speed, so you'd just need the change speed function to get it to normal sound.

[fastcat]

Thank you both for your help. Sorry for the small amount of information. When i said 'high' I ment high pitched. Using the multi filter i get the pitch lower but slower.
Dan, you have answered one question of mine, from what i have read a tape that has be recorded over or deleted can not be retreaved but this doesn't seem to be the case. If you zoom in and go between the voices that are on the video you can see, there is a whole conversation, this is what i am trying to pick out. I have had some sucess.
Any sugestions would be greatly appriciated

[Craig Maier]

Hi,

Analog tapes can retain some "residual magnetism" which produces the effect that you seem to be observing. Digital tapes will not do that. Forensics folks have used DC7.5 to pull off these types of signals from behind the overwritting signal. If they are of the wrong pitch, you can correct that problem using Dan's recommendation.

Craig

[fastcat]

The recordings was made on a sony digital handycam DCR- TRV130E PAL. It is definatley voices and not static I'm hearing. As I have managed to get small snippits as I'm new to this it's like wading through treacle. I will try what has been suggested. Thank you once again for your help.

[Dan McDonald]

Is this the kind that uses the Sony tapes that look like cassettes? If it's about 10 years old, I am thinking that they had digital video and analog (magnetic) audio.

If that's right, then the audio record head probably didn't align closely enough to wipe out the old tape completely. I would think that could happen if the tape was used in two different recorders, or if a repair was done to the camera between the two uses, or if something just knocked it out of alignment.

[fastcat]

Dan, yes it is about 10 years old and the tape is a Sony 8mm GH90 tape.
From the operators manual it reads as follows for the audio recording:
Rotary heads PCM system
Quantization 12 bits (Fs 32kHz stereo 1, stereo 2) 16 bits (Fs kHz, stereo)
Is this of any help?

[Dan McDonald]

sounds like it is digital then. Craig will understand it better than I will.

[fastcat]

thank you for help Dan

[Craig Maier]

Hi,

This is a new one on me. I know of no mechanism by which one digitally recorded signal can impose itself upon the other and have the ability to play back simulataneously. There must be another explanation for this like one of the two channels has one thing on it and the other has something else on it. Or, perhaps, the recorder has both PCM and Analog tracks and the playback switch is set such that they both are summing together during playback (this is a stronger possibility). I have a VHS VCR that does something like that; it has Hi Fi and Linear Audio tracks. One can choose between Hi Fi Audio, Linear Track Audio and Hi Fi Audio plus Linear Track Audio.

??

Craig

[Dan McDonald]

Yes, these Sonys had an odd system of recording where (if I remember correctly) there is a built-in mic and an external mic input, and also a place to plug in their own external mic, but these are different audio tracks, where one is lower quality than the other. I believe the external mic is 16-bit and the internal is the 12-bit. That's where you're getting that one statement about the different qualities. (I'm starting to remember this now). I am pretty certain they are recorded in different places on the tape, which would explain the bleed-through you are getting if you're just capturing what it's playing.

I think I would extract the audio using something like Adobe Elements because it allows for multiple audio tracks. Then, if this is right, you may be able to just delete the tracks you don't want and have the audio from what you want. They probably have a free 30-day trial if you want to see if that helps.

If that works, just extract the audio after you delete what you down't want (adobe can do this easily), save it as a wav file, and put it in dc art and change the speed.

Dan

[Dan McDonald]

If this is the style I'm thinking of, I think that the internal mic was the lower quality, and it was set up so that you could record both internal and external at the same time, and so they put these sounds in different places. It was so that you could get natural sound but also use a mic to get close to the audio action, but there was a change you had to make in the menu setting in order to record both. My guess is that the tape was just re-used, and that the camera wasn't designed to record over a track that wasn't being used, so you have the 'bleed-through' sound you're hearing.

I would go with pulling it off the camera with Adobe or similar software and you should be in good shape.

Dan

[fastcat]

thank you for your help once again, I will have a go at what you have sugested. I will be back and let you know how i got on, but it may be a few days !!
Cheers
Pete