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Problems with exporting Losslessly. Weird aspect ratio and black bars
The Short Story: I try to export some sequences losslessly using the DNXHD codec, and the results are either squashed or have black bars around them. What am I doing wrong?
This right here is the Long Story which adds more context:
I edited a short film together in the Original Project file, and now I need to go in and add the external mics we took with boom. I created a SyncAudio project file and synced all the footage and audio files. Footage was taken with several different DSLRs, and audio is WAV audio files.
I need to export all these files losslessly so that I can replace the old files in the Original Project file, after I do that I will begin color correction and stuff. This is why I’m doing it losslessly is so that I don’t downgrade the quality of the footage that I plan on working with.
When I export, I use these settings:
1920×1080, 29.97fps, lower, quality 100, Avid DNxHD codec
Uncompressed, 48000HZ, Stereo, 16 bit.The sequence settings for the original were the 1920×1080 and yet when I export the ratio looks all screwed up.
Looking at other threads I have discovered that the squished look is probably due to a rectangular pixel issue, but that doesn’t explain the thin black bars at the bottom and top.
Additionally the footage seems to play back reaaaally slow, and choppy. Shouldn’t lossless be smoother because there’s less compression power that needs to be dealt with?
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2 Replies
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Welcome to the forum. Please post screen captures of the sequence settings panel and export panel to help troubleshoot. Images of a frame in the sequence and after encoding would be helpful, also.
[David French] “Looking at other threads I have discovered that the squished look is probably due to a rectangular pixel issue, but that doesn’t explain the thin black bars at the bottom and top.”
Actually, it might. The default settings include both a pixel ratio and resolution. Premiere fits the frame into a default rectangle. Black bars/columns are generated when the sequence doesn’t fit properly.
[David French] “Additionally the footage seems to play back reaaaally slow, and choppy. Shouldn’t lossless be smoother because there’s less compression power that needs to be dealt with?”
The playback issue is likely related to your computer’s system throughput. Although DNxHD is less compressed than delivery codecs like H.264, it still requires decoding. More significantly, its bitrate can exceed the capability of drives and I/O, especially at 1080p.
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Found the square pixel setting and all is well with the world! Works like a charm now.
The slowdown was just when I played the files in VLC, in premiere it works A-ok
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