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Re: Same as source export with different codects on timeline

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Juan Juig
Re: Same as source export with different codects on timeline
on Apr 25, 2020 at 9:30:12 pm

Hi Shane, thank you for the reply!

In the future I most definitely will use a video mixdown. The thing is that usually when I'm exporting from Avid I receive the graded file, that doesn't have any cuts anymore and I just add the opening credits, final credits and perhaps some FX that was rendered elsewhere. Those are usually the elements that are not DNxHD 185x and represent a little percentage of entire timeline.

Would you say that exporting the timeline as "Custom" to DNxHD 185x without doing a mixdown would yield the same (or really similar, without noticable differences) result as doing a video mixdown and exporting it "Same as source" in the specific situation that I have described?

I now also did a test: I imported the same clip with a duration of around 5 seconds as DNxHD 120 and DnxHD 185x.
- I tried exporting both of the clips on timeline as Same as source and the result is strange. Since each codec represents half of the timeline, Avid exports the clip with a different bitrate: in my case 165 Mb/s. MediaInfo doesn't label it as anything specific but it does say it is a DNxHD codec by Avid. When I import it back to Avid it just says "Avid DnxHD Codec".
- When I exported a whole clip as Same as source that was DNxHD 185x and just a few frames of the DNxHD 120 file I got a different result: MediaInfo labelled the exported clip as DNxHD 185x by Avid and the bitrate was in fact 185 Mb/s. However when I brought it to Avid with Source Browser it again only said "Avid DNxHD Codec".
- Exporting only the portion of the timeline where the DNxHD 185x clip was resulted in an expected outcome: MediaInfo labelled it as DNxHD 185x by Avid and when I brought the clip back to Avid it was labelled as DNxHD 185x.

So I guess that if you use the Same as Source export option Avid will always export one ONE sort of codec with a constant bitrate. In the case of mixed codecs it will find a middle way and export it with a non-standard bitrate, but if one of the codecs presents the majority of the timeline it will label it as that particular codec.

I've been an editor for a while and I now believe it was definitely not ok that I sometimes didn't use a video mixdown. But would you say that if the exported files were labelled as DNxHD 185x and I had no issues with them that those files are still ok in a technical sense? I'll be more careful in the future for sure. :)


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