New DV Metadata/Datacode tool

[Colin Browell]

I am currently working on a PC-based tool which started off as a DV media player, similar to the basic Windows Media Player but which allows you to view the timecode, date and time of recording, iris/aperture, shutter speed, gain, white balance, image stabilizer on or off which are embedded in the DV AVI file - in fact all of the info you would normally see in the camcorder's LCD with datacode switched on. You just play the DV file or frame-step backward or forward and see the values change in a pane just below the video.

I'm currently working on extending the program to allow some of this "metadata" to be exported or modified, for example:

- re-write the timecode in the DV file starting from a specified time
(e.g. could be useful to set the hour to a reel number, or force a
particular frame to start from a required timecode)

- change or remove the date and time of recording from a DV file

- strip all metadata (except mandatory) from a DV file

- export metadata as a subtitle file for use in DVD authoring
programs

- export a SAMI file which can be used to view a limited amount
of metadata in an ordinary Windows Media Player, while playing
the DV video file

- restore exported metadata into a DV file


I'd like to poll some opinions on how useful you would find any of these features, or if anyone would like to suggest other "metadata" features they would like to see.

At present the <i>player</i> functionality is in a late development state, but it would be helpful to know what (if any!) features users would find most useful.

Thanks,

Colin

[Robert Knecht Schmidt]

Sounds great, Colin.

One feature a lot of editors might find useful would be an option to burn the timecode data onto a copy of the video footage file. This might be slightly more tricky programming-wise as you'd be dealing with image manipulation and a recompress rather than just metadata values.

Let me know if I can be of help.

By the way, italics are denoted with [ i ] and not <i>. (No spaces between the brackets.) Similiarly you can create clickable hyperlinks with
[ ur l] http://www.mysite.com [ /url ] or
[ url="http://www.mysite.com" ] Here's my site! [ /url ].

[Colin Browell]

an option to burn the timecode data onto a copy of the video footage file.

... and that too.

Thanks Robert.


Anyone else?

[Tavys Ashcroft]

Adjustable playback rate fwd/rev with frame-rate fine tuning and on-the fly deinterlacing would be a dream for previewing slo-mo stuff and working out timing for music videos.

Also, effects based on the aperture, shutter speed, gain, etc settings that are contained in that metadata would be cool. I know that it wouldn't be anywhere near the quality of changing them at the time of shooting, but if it were possible for the effects to take those metadata settings into account and attempt to make at least slight compensations relative to what could be adjusted (brightness/contrast/white and color balance would probably be easier to implement than things like motion blur and dof) it would be a real boon to previewing touch ups. I guess stuff like that would be hard to code, and might be better left for nle programs, but it would be a cool way to use the metadata advantageously.

I like the sound of what you've done so far, though. I love timecode!

What all is in that metadata, anyway?

[Colin Browell]

guess stuff like that ... might be better left for nle programs

My thoughts too. Certainly in the first version I'd prefer to avoid coding a lot of complicated image processing routines most of which could be done in an NLE. I'll note your suggestions though.

Adjustable playback rate should be OK, but reverse playback can be a real problem in DirectShow. I'll have to experiment a little.

What all is in that metadata, anyway?

It is mostly the info that you see on the camcorder's LCD screen when you have the datacode switched on, plus info about the aspect ratio, audio format etc. There is a whole range of extra info defined such as chapters, closed captions and Teletext but these are rarely (if at all) used.

[Rob Lohman]

That's great news, Colin! As you saw in another thread I worked
on a similar program as well, but got stuck on a lack of information
regarding the exact structures of DV and more specially the iris/
shutter settings etc. Did you buy some specs for all of this? I had
a real hard time trying to find which specs would containg what
information.

What language are you programming this in? Since I'm a
programmer myself let me know if I can help you out with anything
or things like (beta) testing.

[Colin Browell]

Yes, I gave up trying to reverse engineer files a while back. You can only go so far.

Did you buy some specs for all of this

You can call me crazy if you like! I haven't yet decided how to release the tool, but I may ask a small registration fee for a full-featured version. At least that will help to offset the cost of the specs.

I'm using C++ and DirectShow (which does not have any support at all for DV metadata). I've got most of it sorted now - it's just a matter of coding up the last few features and tidying up any memory leaks.

Hopefully it will work with DV50 too, but I may need to ask for a file sample to check it out.

Thanks for the encouragement. :)

[Rob Lohman]

DirectShow doesn't indeed. That's why I wrote my own basic
DV parser. So which specs did you get? I think I know which one
is the basic DV spec, but I scanned through that one at IBC and
there was no mention at all about the DV fields like shutter
speed and iris etc. Now I have found out which fields those are
for my XL1S (PAL). But I haven't found a way to interprete these
numbers, as of yet. I also got the feeling that this might be
different depending on brand & model (for example, my XL1S
doesn't seem to store all relevant information, only a couple of
settings?).

Which specs did you buy? Again, I could not find a spec for the
VAUX camera information.