Splice, can I assume that technique depends on my ears having decently matched responses?
I'm capturing VHS home movies on a VCR with stereo linear audio heads. The tapes I'm currently working with have only a mono track, but I get occasional distracting hitches in the audio that are only present in the right/left captured channel and not the other, so I need to collapse the audio into a single mono channel in software to fix them. (Well, I have to normalize the channels to equal volume first, since their relative volume depends on how the tape was recorded.) This means I have to worry about sound cancellation from phase differences. I'll probably end up correcting the audio phase in software anyway with Stereo Tool, but I'd like to start out with a properly aligned VCR at least.As a result, I'm now trying to calibrate the azimuth for my VCR's linear audio heads, and it's a huge pain. I've done it before by comparing channel differences with a pretty high-latency method: Capture part of a tape with Virtualdub, export the audio to .wav, import to Audacity, normalize the channels separately, split the stereo channels, invert one, rejoin the channels into stereo, then collapse the channels into mono for the difference between the two channels after normalizing. Then turn the azimuth screw a bit, do the whole process over again, and compare the two differences to see whether I made it better or worse...lather, rinse, repeat. I've spent all day doing this before, and I eventually got my VCR aligned to my satisfaction (the difference track was very faint), but I've recently found that it's all out of alignment again. I'd hate to spend just as much time doing it this way all over again, so I'm looking for better tools.Is there any Windows or Linux software that can visualize or otherwise report phase differences in real-time (or with some reasonable latency)? I would love to have something that worked on line-in audio, so I could turn the screw and get real-time feedback, but even having something that worked on a .wav file would save me a lot of time. ProPhase seems to do this, but it's MacOS only, and I'd like to find something I can actually use. Thanks
Real time PC-based oscilloscopes and other analyzers are out there.
What is the test tape that you are using?
Quote from: Arnold B. Krueger on 27 July, 2012, 12:54:04 PMReal time PC-based oscilloscopes and other analyzers are out there.Where? I have never found anything but huge, unwieldy and expensive audio workstation appliances that do this. Is there a freeware PC software or VST plugin that does e.g. Lissajous figures from stereo audio input?
I think Cool Edit Pro will let you visualize a Lissajous pattern showing the relative phase of the two channels and you can tweak your azimuth from that, but I'm not sure.<snip>
The OP's objective is not to maximize HF on each channel. The recording is mono material, but with dropouts in one or the other channel. What he wants to do is phase match the two channels and convert to mono without destroying the HF due to phase mismatch.Edit: What he perhaps should be doing instead is using azimuth adjustment to maximize HF, then after digitizing, shift one channel to get phase matching between channels before converting to mono.