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Problems with video from GH2 - audio and IQ

Discussion in 'Video Post-Production' started by f6cvalkyrie, Sep 25, 2012.

  1. f6cvalkyrie

    f6cvalkyrie Mu-43 All-Pro

    Feb 12, 2010
    Brussels, Belgium

    last weekend, I shot an 8 min video of the yearly fireworks in our village.

    Hardware used :
    GH2 (not hacked) with 16GB Cl 6 SanDisk Ultra
    14-45 mm Pana lens
    Rode SVM stereo microphone (on-camera)

    The first 3.5 min, the result is quite good. Sound is crisp and video is not pixelated.
    However, after 3.5 min, the image gets (heavily) pixelated, even in the original .MTS file (I used AVCHD 720 setting). Sound remains present and good in the .MTS file during the whole clip, but, when importing the file to Adobe Premiere Pro, after 3.5 min, I also loose sound :confused: :confused: 

    For your information, I shot another film of 20 min during the afternoon of the same day, with the same equipment and settings, with no problem at all ???

    I'm grateful for any info pointing into the direction of a solution, especially for the non-imported sound after 3.5 min ! Imagine a clip of fireworks with no sound :eek: :eek: 

  2. Wasabi Bob

    Wasabi Bob Mu-43 All-Pro

    Things to consider

    Pixelization usually is attributed to a read or write data error. My first suspicion would be the memory card. When shooting video I always start the project by formatting the card in the camera - never on a PC. This reduces the possibilities of the file being fragmented.

    Another thing to consider is were the conditions when the problem occurred different than the next session? By different, I mean was it very hot, or was you camera stored in the trunk where it might have been very warm?

    Suffice to say, if you can't repeat the problem, you can't fix it. I have seen this occur on cameras that were "hacked" and later converted back to the original firmware. The hacked firmware really raises the operating temperature of the Venus engine and it does not take much to cause some thermal damage to the IC. I know of two people who sustained such damage - it was an expensive ($700) mistake!
    • Like Like x 1
  3. f6cvalkyrie

    f6cvalkyrie Mu-43 All-Pro

    Feb 12, 2010
    Brussels, Belgium
    Thanks for your reply, Bob !
    I agree with you, and I replaced the memory card with a 32GB class 10 Sandisk Extreme Pro (writing at 95 Mb/s)
    Two weeks ago, I shot another film, with 1080 setting - 24 fps. The pixelization did not occur, but I ran into numerous other problems in the editing process in Premiere Pro an After Effects

    Clearly, shooting and editing video files is a completely different ballgame :frown::frown:

    I think that I also attribute the pixelization problem to the fact that the concerned shot was an 8-minute uninterrupted scene, while the afternoon shoot was composed of many but shorter clips ...

    C U
  4. ChipThome

    ChipThome Mu-43 Regular

    Jul 8, 2011

    Duration should have no affect, as long as the card can take what the camera is sending. You should be able to record constantly as long as you have battery power and card space.

    Premiere Pro and I believe, also After Effect rely on a CUDA capable video card to do some of the heavy processing. One way to determine if it may be your video card, and not Premiere or your file would be to render out your timeline to H.264 and then view that file on your computer. If that file plays correctly, start looking at your video card to see if it is CUDA enabled.

    Before my most recent card and making sure Premiere recognized it, the playback window in Premiere showed terrible quality, but finished files were perfect.
  5. powderbanks

    powderbanks Mu-43 Regular

    Dec 7, 2012
    north carolina
    i was shooting some 720p/60fps footage yesterday and reviewing some of it, there is a gap in the audio. it was in the middle of a ~5min clip, so that was odd.

    with premier, it has to 'conform' the waveforms to get the audio playback. usually this is most notable when you're first loading a file into premier. depending on the speed of your computer, it can take a while with longer clips. but you'll have video, and the audio will drop out. keep an eye on the bottom right corner, and if you see a 'conforming ***.MTS' and a progress bar, let it go and your audio should come back.

    are you having stuttering during playback? mts files are very compressed, and iirc, it's more processor intensive than other codecs. if you're working with some high bitrate footage (lots of detail, all in focus), it can cause stuttering during playback. best thing to do is to adjust the playback resolution. most of the time i have it set at full, but you can go down to 1/2 or 1/4 resolution for playback. look for the little tab on your viewer window that says 'full' and you can toggle it between the different resolutions.
  6. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    As already stated, sounds like a card write error. Of coarse this is far less common in flash cards as opposed to tape. I had to go back and shoot a couple of times because the tape flubbed and had to eat one project completely because of it{event that could not be redone}.
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