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MPEG Streamclip – thin black bars after 1080 to 480 QT DV export
Hello Everyone,
I need to convert 1080i QT video (a few thousand clips) to 480i in DV codec, and after doing some tests with Compressor and MPEG Streamclip, I decided that I like the quality of MPEG Streamclip (version 1.9.3b7) over Compressor.
However, after the 1080 to 480 (Apple DV codec) conversion, the new 720×480 Quicktime clips has very thin black bars on the side of them.
I checked the “16×9” option, and the 720×480 clips are ALMOST widescreen, aside from the thin black bars, which also result in the converted clips being a bit horizontally squished.
Does anyone have an idea of why the black bars are there, and if there is a setting I can use to remove them and have a true 720×480 image?
Thank you very much for your ideas and help.
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5 Replies
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I was just reading the manual for MPEG Streamclip, and there is a “Scale” feature in the “Cropping” option, where you can remove pixel lines from either or all of the four corners of the image, and then the image will be stretched to maintain the designated end dimension…
I just have to guess (or use trial and error) to determine exactly how many black pixels are on each side…
I hope this might help someone else who is experiencing the same issue.
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I finally found a solution and the right settings in MPEG Streamclip for an accurate conversion from 1920x1080i Quicktime to 720×480 Apple DV.
In the spirit of helping anyone else who is frustrated and unsure of how to address the black side bar issue, here are the settings that I used that worked in my case:
(Some of these are obvious, but I’m including them just to be thorough)
1) “Compression”: Apple DV/DVCPRO –
NTSC2) in “Options” choose “Interlaced” and “16:9”
3) “Quality”: I choose “100%”
4) check the “Cropping” box
5) Under “Cropping,” choose “Scale”
6) Under “Cropping,” for “Left” enter “9,” and for “Right” enter “8” (I don’t know why the pixels aren’t the same width, but I tested outputs with several pixel cropping variables, and these seem correct and remove the all of the black side pixel bars, and in my observation, no image pixels.
Below is the information from the MPEG Streamclip manual regarding the Cropping feature:
Cropping
With this feature, you can crop any edge of the frame: you just have to enable it and
enter the amount of pixels you want to crop from each edge. Even numbers are
preferred. Negative numbers are allowed: in most cases, they will add a black border to
the picture.
You can choose between three different cropping modes: “Destination”, “Source”,
“Scale”.
With “Destination” (the default mode), cropping is relative to pixels in the destination
movie, and the frame size of the resulting movie will be changed.
With “Source”, cropping is relative to pixels in the source movie; the frame size of the
resulting movie will not be changed, and the picture is stretched to fit the destination
frame size.
With “Scale”, cropping is relative to pixels in the destination movie; the frame size of the
resulting movie will not be changed, and the picture is stretched to fit the destination
frame size.
Note however that If you choose the “Destination” cropping mode with a DV frame size,
MPEG Streamclip will use “Scale” instead. -
In case anyone was wondering why we are downconverting 1080i to 480i…
We are editing a feature documentary film with about 500 hours of 1920×1080 footage, and even with the 9TB RAID that we have, that is not enough close to the space we need.
So, we decided to do an offline edit in SD, with all of the 500 hours of footage converted to SD able to fit on our 9TB RAID.
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Did you try to convert them to Prores Proxy in Log and Transfer? Some times I have found that dv uses more space than Prores.
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Hi Daniel,
I appreciate your thoughts and suggestions.
Yes, Prores proxy could have been an option.
HD Prores Proxy bitrate is 45 Mbps, and DV SD Bitrate is 3.6 Mbps.
But, for this film, we are working with about 500 hours of HD footage, and we have a 9TB RAID, so we would not have enough space for 500 hours of 1080i prores proxy.
Thanks again for your thoughts and input.
Khashyar
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