Posted: Mon 26 Mar 2007, 2:02 Post subject: just find a Final Cut Pro's fault
I just use FCP (latest version) to creat a pal (resolution=720x576) project, and import a mpeg2 encoded m2v file with resolution of 720x576, the PAR is 1.067. to my surprise, the imported file does not occucpy the whole monitor windows of FCP, it's a little smaller.
I then check the imported files' property in FCP, it's 720x540 in square pixels! since pal frame in square pixels is 768x576, then that's the reason--- FCP scales the imported file to 720x540 instead of 768x576.
I think that is a FCP's fault. as we know, hunman eyes are more sensetive to the vertical resolution than to the horizontal resolution. FCP should keep the vertical resolution of 576 lines, and scale the horizontal resolution to 768. but FCP does the job in the opposite way.
BTW, I'm new to FCP. anyone know how to let FCP scales imported video/graphic to full frame automatically? thanks.
Joined: 04 Feb 2003 Posts: 587 Location: Lisboa, Portugal
Posted: Thu 29 Mar 2007, 21:50 Post subject:
Human eyes aren't really more sensitive to horizontal or vertical resolution. The reason to keep the vertical resolution has to do with video interlacing; resizing interlaced video needs to treat each field separately, so it's usually simpler to resize only the horizontal dimension (which can be done by treating the frame as a single image).
I'm not sure what you mean when you say the file is "720x540 in square pixels". Aren't you working with a PAL project? If so, the pixels aren't supposed to be square. On-screen (during preview), it doesn't really matter what the size of the image is; it will usually be scaled to match the size of the window anyway (in other words, it might as well be 320x240, 400x300, 1024x768, etc.). As long as it has the right aspect ratio, you can trust it.
What really matters is the size of the files being output. If your project is 720x576 (PAL), and your input files are also 720x576 (PAL), the output should be correct.
as for "eyes are more sensitive to vertical than horizontal resolution", I did see it from quite a few places, but don't remember where.
and the other problem.
different softwares report video resolution in different ways. some may report the origional physical resolution, such as a pal dvd m2v file is reported as 720x576. and others report the resolution after scaling to square pixels. and FCP does it in the later way. so for a pal dvd m2v file, fcp scale it to 720x540 and report that resolution. but strangely, FCP'S pal project's resolution, the resolution which FCP works at, is 768x576 in square pixels. so although the frame ratio of m2v file after scaling is still 4:3, but it has fewer pixels than the pal project has. then the m2v file is located in the center of the project's frame with some thin black area all around the m2v file. wish I have made the problem clear.
I think it's FCP's fault to scale the m2v file to 720x540 instead of 768x576.
Joined: 04 Feb 2003 Posts: 587 Location: Lisboa, Portugal
Posted: Fri 30 Mar 2007, 22:59 Post subject:
compusic wrote:
FCP'S pal project's resolution, the resolution which FCP works at, is 768x576 in square pixels.
If the project is DV (or any other CCIR601 standard), that makes no sense. PAL is 720x576, period, it doesn't make any sense to talk about "square-pixel PAL", because PAL (CCIR601) does not use square pixels.
I don't have a FCP system at this time, but I suspect there is some other issue going on there (ex., using an analog capture card).
All editing software should report the project and file dimensions exactly (project dimensions = output resolution, file properties = original file resolution).
well, this relates to another topic I have posted, whether NLE software process video datas in square pixels, or rectangle pixels if the project setting requires? supposed the imported videos have all kinds of pixel ratios.
yes, the pal project is 720x576 WITH par=1.067. but computers display videos in square pixels, right? then in fact, FCP will display the video in 768x576 in square pixels in its prewiew window, supposed a 100% preview window. and I think FCP will also scale the imported videos if those videos are not in square pixels. as for my example, a pal dvd m2v file, though the origional resolution is 720x576 w/PAR=1.067, FCP will scal the m2v file to 720x540 in square pixels. that's the fault! I'm afraid FCP should scale it to 768x576.
Joined: 04 Feb 2003 Posts: 587 Location: Lisboa, Portugal
Posted: Sat 31 Mar 2007, 6:06 Post subject:
By definition, if the video is meant to be displayed with rectangualr pixels and the PC screen uses square pixels, "100%" cannot mean 100%. It can mean the same horizontal size, or it can mean the same vertical size, but it can't mean both things.
Most software keeps the vertical resolution and resizes horizontally because it's easier. But resizing vertically is also an option (if you want to keep "100%" of the horizontal resolution). In fact, by resizing vertically, you can make PAL and NTSC videos the same size (because they both have 720 pixels per line), which makes the program's interface more consistent.
If your output settings are set to DV PAL, why would FCP scale the videos to 720x540? And why "should" it scale them to 768x576? It should obviously export them with the original size (720x576). Resizing them would not only degrade the quality, but would be a complete waste of time.
The only thing that needs to be resized is the preview window, so the image's aspect ratio doesn't look wrong. But the actual size of the preview window is irrelevant, it doesn't affect processing. You cannot see PAL (or NTSC) with a 1:1 pixel reproduction and the correct gamma curve on a computer screen anyway. Video editors always use an external (video) monitor to see the result. The preview window is just that: a preview.
well, the most important problem is that the imported pal m2v file does not occupy the whole frame of the FCP pal project. no matter what method the computer and software use to display video, I'm afraid the pal m2v file should occupy the whole frame of the FCP's project. in fact, it has nothing to do with output or external monitor.
Joined: 04 Feb 2003 Posts: 587 Location: Lisboa, Portugal
Posted: Sun 8 Apr 2007, 16:26 Post subject:
I'm pretty sure that if FCP was unable to correcly load PAL files into a PAL project, someone would have noticed it (and fixed it) by now.
You might run into some problems or "quirky" behaviour when converting between standards (ex., loading a square-pixel file into a PAL project, or a PAL file into an NTSC project, etc.), but PAL-on-PAL should work fine.
well, just confirmed the problem once more. but I'm not familiar with mac system, so don't know how to grap a pic.
this time the same m2v file was checked in both windows and mac system.
in windows, the file info is correct, 720x576 w/PAR=1.067, and in mac in FCP, the info is 720x540 w/PAR=1.0, the FCP's project format is pal.
below is a reply from another forum:
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"Its not FCP being incorret on import it is quicktime see below.
"Quick-Time player always assumes square pixels, so "PAL" always plays in a 5x4 shape, irrespective of the supposed image shape. If QT is informed that the image is 4:3, it takes the width (720) and reports height as 3/4 of that (540)."
I assume if you are importing MPEG2 into FCP that you are going to do some sort of editing to the file. You are better off getting it into a native QT format such as DV, get your hands on a piece of freeware called MPEGstreamclip which will transcode to any QT format, this also has the bonus of no rendering in FCP. "
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and then is my further reply:
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"crusty wrote:
If QT is informed that the image is 4:3, it takes the width (720) and reports height as 3/4 of that (540)."
though I'm not sure which one, the FCP or QT, does the scaling job, the problem here is why not take the height (576) and report width as 768?
I usually edit uncompressed files. this problem is just found by accident. "
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Joined: 04 Feb 2003 Posts: 587 Location: Lisboa, Portugal
Posted: Wed 25 Apr 2007, 1:40 Post subject:
It shouldn't do either. If your project is in PAL, it should retain the original dimensions (720x576). There is no reason to convert to a square-pixel format when your project is in PAL (which does not use square pixels).
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