Grainy Video

Discussion in 'Digital Video' started by izz, Aug 18, 2008.

  1. izz macrumors newbie

    Joined:
    Aug 18, 2008
    Location:
    Melbourne - AU
    #1
    Hi,

    I have been uploading footage taken with a Sony HVR-V1P (PAL) onto my imac 2.4ghz, 2gb ram.

    They problem I have been having is that the footage appears grainy, and even blocky in some places (low light). This is the case in both Final Cut Pro 6 and imovie.

    I have exported the file out to DVD in the hope that it would correct itself but in all honesty it turns out worse. It looks fantastic when played back straight from camera to HDTV.

    The footage was shot at 25p (50i)

    Any help with this would be greatly appreciated.
     
  2. cpcarrot macrumors member

    Joined:
    Jan 24, 2008
    #2
    Generally speaking the grain that you are seeing is caused by the camera amping up the gain and thus introducing electronic noise into the image. There will be a way of controlling the exposure on camera so that you just open up the aperture as much as possible and don’t let it add any gain (not familiar with that camera so not 100% certain how to do it on that one). The image will be darker but without grain.

    The above said, I don’t know why it would look fine on a HDTV if that was the case as it would be recording the grain and therefore should be evident on the TV as well. Hopefully someone else can shed some light on this…
     
  3. izz thread starter macrumors newbie

    Joined:
    Aug 18, 2008
    Location:
    Melbourne - AU
    #3
    Thanks for the reply cpcarrot. I'm actually thinking that the imac screen isn't showing all the pixels, in which case the image looks like it has grain in it. The camera was set-up in the correct way and as it looks great on the HDTV or any other TV (SD) for that matter, it can only be - either the way it was captured, or that the imac can't handle the HD footage. I will find out (hopefully) when I plug in an HD monitor as a second screen (through DVI to HDMI)...

    Thanks again.
     
  4. cpcarrot macrumors member

    Joined:
    Jan 24, 2008
    #4
    If it's the 20" model it wouldn't show the full resolution (24" would) and would have to downscale the footage. But normally viewing it at a lower resolution would mean you are less likely to see any grain than the reverse so again I'm unfortunetly not sure what to make of that.

    What resolution is your HDTV? I'm assuming it supports the full 1080 lines resolution?
     
  5. Lunja macrumors 6502

    Lunja

    Joined:
    May 15, 2005
    Location:
    Lincoln UK
    #5
    I get something similar in Premiere Pro - my slug and viewer windows always display footage at a lower resolution (possible to save on VRAM?), however my video monitor, showing the timeline output, displays it in full res.

    If possible, hook up a TV or other display as a full-screen output monitor and check this display while you are editing.

    EDIT: You've just said that you're going to do that lol :rolleyes:
     
  6. izz thread starter macrumors newbie

    Joined:
    Aug 18, 2008
    Location:
    Melbourne - AU
    #6
    I have a second LCD screen hooked up now (Samsung 2493HM) through DVI to HDMI and the quality is better, but still nowhere near the quality of straight from camera to my HDTV, which is Full HD. I understand that the footage coming from the computer is of course compressed, but thought it would be a little bit better than what I'm seeing.

    I'm using the Samsung screen in FCP as Digital Cinema Desktop Preview - Full Screen.
     
  7. cpcarrot macrumors member

    Joined:
    Jan 24, 2008
    #7
    OK

    A couple of assumptions to go through:

    1. I assume when you say you are putting it straight from the camera into the TV you are recording the footage first and then playing it back through the HDMI link into the TV and not just feeding the output from the camera straight into the TV without recording it and then playing it back? The unrecorded output is uncompressed and so will be higher quality than the HDV recorded footage.

    2. I am assuming you haven’t converted the footage in anyway, and if so the footage on your computer will be no more compressed than the footage you have recorded on camera. HDV is still HDV. Although if you are importing it via iMovie rather than Final Cut this will be converting it to the Apple Intermediate Codex which could potentially result in some quality loss, so if that’s how you did the import I would suggest just importing with final cut’s log and capture facility as this will keep it in the original codex the whole way.

    In principle the image on your second display should be a more accuate representation of your footage than outputting it back on the TV. What make and model TV is it your viewing it on? Things like the contrast ratio may have an effect on what your image looks like on the TV compared to the monitor.
     
  8. izz thread starter macrumors newbie

    Joined:
    Aug 18, 2008
    Location:
    Melbourne - AU
    #8
    I used the ProRes 422 (HQ) codec to capture with then burnt a test to a dvd - which, while just standard def, actually turned out to be alright. Just minor pixel loss, but that's to be expected. Think I might have nailed it now. Hopefully...

    Thanks guys.
     

Share This Page