1080i + pixel aspect ratio in FCP?

Discussion in 'Digital Video' started by zim, Nov 30, 2006.

  1. zim macrumors 65816

    zim

    Joined:
    Jan 5, 2002
    #1
    Hello,

    Do I need to set the pixel aspect ratio to anything special when working with 1080i (1920x1080)? FCP has three HD pixel aspect ratios: HD (960x720), HD (1280x1080) and HD (1440x1080) or can I just leave it set to NTSC?

    Thanks :D
     
  2. LethalWolfe macrumors G3

    LethalWolfe

    Joined:
    Jan 11, 2002
    Location:
    Los Angeles
    #2
    What is your HD source? HDV is 1440*1080 and DVCProHD is 960*720. If you use one of the easy setups it'll make sure all the settings are correct for the format you choose.


    Lethal
     
  3. zim thread starter macrumors 65816

    zim

    Joined:
    Jan 5, 2002
    #3
    Thanks for the reply.

    The project is composed of SD footage, DV, which will be segmented (divided into 4) quadrants. This is for an exhibition, the work will be seen from a distance (up high) and I have already acknowledged that some softness will occur due to the scale increase (did a test from a still and it looked fine (the work is abstract so it should render well). My instructions were to make the final video 1920*1080, which is the 1080i setting in FCP but I am confused with the whole pixel aspect ratio.

    Would a video with a frame of 1920*1080 set to the NTSC pixel aspect ratio work with an HD screen?
     
  4. LethalWolfe macrumors G3

    LethalWolfe

    Joined:
    Jan 11, 2002
    Location:
    Los Angeles
    #4
    I would maybe use the easy preset for Apple's Intermediate Codec at 1080i60 or the DVCPro HD codec at 1080i60. I assume using an NTSC pixel aspect ratio for a Non-NTSC res (HD) might not look right.

    How are you delivering the video (tape, hard drive, etc.,)?


    Lethal
     
  5. zim thread starter macrumors 65816

    zim

    Joined:
    Jan 5, 2002
    #5
    Why does the Easy Setup window lists the Playback Output for the 1080i60 setting as 1920x1080 but yet the Sequence Settings give a frame size of 1280x1080, pixel aspect ratio of the same. I think this is where all my confusion has started.

    Unfortunately the curator for this event only seems to know to say 1920x1080 and hasn't been able to provide any other information, it is also a brand new exhibition space so the technology is new to them. I believe that they are playing the videos from a computer so with that logic and my understanding from the FCP book, I should be able to just work with the setting of 1920x1080, Pixel aspect ratio of Square (the FCP book describes this as an option for uncompressed HD).

    Going back to my reading, the FCP books are very helpful but don't seem to be answering my question yet.

    Thank you Lethal for all your responses. I think the answer is there I just wish I had a way to test things out, no HD equipment on my end. As for transporting the work, digital files on DVD. The projects are only 1min long and there are 3 of them. If the end file size is larger then a DVD then the exhibition curator will send me a drive by mail.
     
  6. Proto Media macrumors member

    Joined:
    Apr 25, 2006
    Location:
    Gnar Cal
    #6
    the 1440 is for HDV

    the confusion you are getting is caused by HDV. HDV is not true HD, and therefore is not filmed natively in 1920x1080. To get HD onto a mini DV tape, they scale it down to 1440x1080. When you import this footage into FCP, FCP knows that it is HDV, and knows that the pixel aspect ratio needs to be adjusted. This is caused because computers use sqaure pixels, and video uses rectangular pixels (the actual pixel dimension is exactly the same, the difference is in the amount of space BETWEEN pixels.)

    so FCP knows to take this HDV footage and stretch is out horizontally to 1920. Think of HDV as a bigger version of anamorphic footage. anamorphic footage is recorded distorted, and then when you import it, you designate that it is anamorphic, and then FCP knows to stretch it out to make it widescreen.

    if you are delivering some sort of quicktime file to the museum or whatever, leave the pixel ratio to sqaure. This will actually make it look better because the computer wont have to rescale anything and can display it in its native res.

    so hopefully to answer your question, yes, use 1920 x 1080 with a sqaure pixel aspect ratio. also set the interlace field to none. Since you will be displaying it with a computer, it is not neccesary to designate the interlace order. hope this helps, post back if it doesn't and ill try to help you out.

    - Ryan
     
  7. killmoms macrumors 68040

    killmoms

    Joined:
    Jun 23, 2003
    Location:
    Washington, DC
    #7
    No, the difference is not in the space between pixels—the frame is merely stretched out to 1920 x 1080 for display. It's recorded squeezed in to 1440 x 1080, meaning there's a loss in horizontal resolution. The same principle is applied to the anamorphic squeeze on DVDs. The human eye notices a loss in vertical resolution much more than one in horizontal resolution, so space can be saved by losing some of that data and "squeezing" inwards.

    Since you're playing back the finished project with a computer, I'd suggest using a 1920 x 1080 Uncompressed 8-bit HD with square pixels project and then exporting it as that, to compress to a more playable codec (playing uncompressed 1080 HD requires 350MB/s transfer from the HD, which you won't find outside of a 4Gbps FiberChannel RAID). Definitely verify that this is your output target though—if you need to lay it off to some other format, that'll have an impact on what you should do in FCP to make it as efficient as possible.
     
  8. zim thread starter macrumors 65816

    zim

    Joined:
    Jan 5, 2002
    #8
    Okay... The gallery just sent me an updated pdf outlining all the specifications in detail. They want square pixels, 1920 x 1080.

    Thanks to everyone for the great responses, I've learned :D

    So now off to render..

    Correct me if I am wrong but about 60 seconds of HD, uncompressed, will be about 10GB.. eek! I might be asking them to send me a drive to transport the footage. They give me the option to use animation or graphics for compression so might have to give one of those a try (doubt it will reduce the file that much).

    Thanks again!

    So I did a test using the animation setting. 1 min of footage (each film is 1 min long) came out as a 2.84GB file, which will fit onto a DVD :D Thanks again.
     

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