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Posted by Tim Streater on 10/06/52 11:51
In article <4gfsoiF1nco23U1@individual.net>,
"PTravel" <ptravel@ruyitang.com> wrote:
[...]
> Video isn't rendered to DVD. The process should be this:
>
> 1. D-25 video is captured bit-for-bit to a DV-codec-encoded AVI.
> 2. The video is edited, i.e. transitions, titles, effects and corrections
> are added.
> 3. The edited material (anything other than simple cuts) is rendered, i.e.
> the software creates new frames that incorporate the title, effect,
> transition, etc.
> 4. The resulting finished video is transcoded to mpeg2. Transcoding is the
> actual translation of the D-25 video to mpeg2, which is required by DVD.
> 5 The DVD is authored, i.e. menus are added and the mpeg2 is sliced into
> DVD-compliant VOB files. The video isn't altered, but merely repackaged to
> comply with the DVD spec.
> 6. The DVD is burned.
>
> Some software, mostly entry level, will do all six steps.
>
> From the standpoint of video quality, step 4, transcoding, is the most
> critical. Mpeg2 is a lossy, temporally-compressed format, i.e. data gets
> thrown away by this step. Which data and how much of it gets tossed is
> determined by the transcoding software. The transcoder has a lot of
> decisions to make about how to compress the video. As a rule, the most
> optimal compression takes the longest time. Accordingly, entry-level
> packages usually introduce signficant compromises so that transcoding
> doesn't take too long.
>
> > That is, if I bought Final Cut, and used it instead of iMovie,
> > do I just get a lot more editing capability, or do I get a better visual
> > result on the DVD (starting from the same camera-video, that is) as well?
>
> If you're getting poor quality video, it's not because of the editing
> program (Final Cut Pro is an editing package), but because of the
> transcoding. As I said, I don't know Mac, so I can't make any
> recommendations. On my PC, I edit in Adobe Premiere Pro, a prosumer-level
> editor comparable to FCP. Though Premiere can burn DVDs from the timeline,
> I only use it for editing. Once my project is finished, I save it as AVI
> (or frame serve, but that's another discussion altogether) and then use a
> program called tmpgenc, which is a dedicated standalone transcoder. To give
> you an idea of what I meant about compromise, transcoding a 2-hour video
> with tmpgence tweaked to its most optimal settings for video quality can
> take up to 20 hours on my 3.2 Ghz P4 with 1 gig of RAM. Once the video has
> been transcoded to mpeg2, I author in Adobe Encore and burn with Nero. The
> DVDs that I produce approach commercial DVDs in technical (if not artistic)
> video quality.
That's very helpful. Part of my ignorance was which step took place
where. That's clear now and much appreciated.
-- tim
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