Is digital video re-encoded during capture?

[prohtex]

Can someone (who is patient enough to read through all of this) tell me definitively which of these scenarios is in fact accurate?

SCENARIO 1:

When a digital video camera records video to Mini-DV tape, it is encoding that video, on the fly, in the (lossy) DV codec, and writing it to tape. When the video is captured from the camera with a NLE such as Final Cut, the application is simply copying, not re-encoding, the video.

Thus, capturing video in Final Cut in any codec other than DV means FCP will re-encode video to that other codec as it copies it off the tape. Capture with DV codec = copy, (one generation of artifacts). Capture with other codec = re-encode (two generations of artifacts).

SCENARIO 2:

When a digital video camera records video to Mini-DV tape, it is encoding that video, on the fly, in the (lossy) DV codec, and writing it to tape. When the video is captured from the camera with a NLE such as Final Cut, the application is always re-encoding the video into a new codec, typically the same DV codec used by the camera.

Thus, video captured in Final Cut will always have two generations of artifacts, one from the initial in-camera encoding, and one from the application re-encoding, regardless of which codec is used the second time.

SCENARIO 3:

When a digital video camera records video to Mini-DV tape, it is writing raw (lossless) digital video. When the video is captured from the camera with a NLE such as Final Cut, the application then encodes the video in a given codec, typically DV format.

Thus, video captured in Final Cut is always subjected to just one generation of artifacts introduced during capture, regardless of which codec is used.

???

 

[prohtex]

PS - In case you are wondering, I am asking this question because I have a Panasonic DVX that shoots SD video and I am trying to find the workflow in Final Cut Pro that results in the cleanest overall image. It seems silly to "capture" to Intermediate Codec (or similar) if the video coming out of the camera is already encoded in a lesser codec.

It is also confusing that each sequence has codec settings - does this mean that if I have multiple nested sequences, each parent adds another generation of artifacts? Or does FCP intelligently sub-render only the parts of the sequence that use effects, time remapping, etc, copying out the rest without re-encoding? Does the same hold true for nested sequences with codec settings that differ from their parent? Or, is the sequence codec setting only a kind of bookmark that effects exporting just that sequence as a standalone file?

I guess I want to know if FCP is internally re-encoding video according to the sequence settings to process video effects and nested sequences, and how to best avoid extra generations of artifacts before the final encode to SD DVD (which itself is very lossy of course)

Help much appreciated!

 

[Shane Ross]

When you capture a DV tape from a camera or deck via firewire, it is a simple data transfer. Zero quality loss.

As Andy Mees pointed out on another forum.

 

[prohtex]

So what you are saying is, when FCP is set to capture into DV codec format, it performs a bit for bit copy (because the source is already encoded in that codec), BUT when it is set to capture to a different codec, like Intermediate or ProRes, it copies, then re-encodes the video in the new codec?

This produces unnecessary additional artifacts right? Can anybody tell me why I would want to do my capturing and edit workflow in another codec than DV?

 

[adkimery]

So what you are saying is, when FCP is set to capture into DV codec format, it performs a bit for bit copy (because the source is already encoded in that codec), BUT when it is set to capture to a different codec, like Intermediate or ProRes, it copies, then re-encodes the video in the new codec?

Correct.

This produces unnecessary additional artifacts right?

On paper yes, but in reality not so much. I think you'd be hard pressed to tell the difference between a DV original clip and one transcoded into ProRes.

Can anybody tell me why I would want to do my capturing and edit workflow in another codec than DV?

If you shot on DV and your final product will go back out to DV there is no reason to work in anything other than DV. But if your final product is for DVD, the web, broadcast, etc., then working in a higher quality timeline when doing things like color correction and applying gfx will yield better results because those things won't be subject to the DV compression. Also, sometimes if you are working w/many different types of source material (VHS, BetaSP, DigiBeta, DV, etc.,) transcoding everything into a single, high quality codec (ProRes, uncompressed, etc.,) is much easier than trying to juggle a half dozen different formats in the same project.


-A