Transcribing documents and A/V

[Paul Allen]

I am building a site for transcribing parish registers of births and marriages using Omeka + Scripto plug-in. I wonder if there's a way of superimposing rulers at the top/bottom and left/righthand sides to allow the transcriber to refer to locations on the image? Ideally, the rulers (or x-y grid reference of some kind) would zoom in/out with the image as the transcriber interacted with the image. Any suggestions? The other - less appealing alternative - is to batch process the original images to add the rulers before uploading them to Omeka. 

On a similar note, I'm also building a site for transcribing audio/visual materials - and wonder if there's a way (besides manual annotation) and synchronizing the entries in the transcription with a location in the media?

Thanks in advance.

Paul