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How to get "single field" preview with DV capture? - Mac Programming

Hi Folks, I am trying to get a good image quality from the sequenz grabber component while playback/preview. I found the "SGSetChannelPlayFlags" function and called it with the "channelPlayHighQuality" constant. The result is pretty nice but now I have the interlace problem. I was not able to find anything like "playSingleField" -- to bad that the "SetMediaPlayHints(hintsSingleField)" functions works only on Quicktime movies. Any suggestions on how to get deinterlaced or single field preview? Thanx Markus...

  1. #1

    Default How to get "single field" preview with DV capture?

    Hi Folks,

    I am trying to get a good image quality from the sequenz grabber
    component while playback/preview. I found the "SGSetChannelPlayFlags"
    function and called it with the "channelPlayHighQuality" constant. The
    result is pretty nice but now I have the interlace problem. I was not
    able to find anything like "playSingleField" -- to bad that the
    "SetMediaPlayHints(hintsSingleField)" functions works only on Quicktime
    movies.

    Any suggestions on how to get deinterlaced or single field preview?

    Thanx
    Markus
    markus Guest

  2. #2

    Default Re: How to get "single field" preview with DV capture?

    In article <20040427190219903+t-online.de>,
    markus <de> wrote:
     

    You can get a reference to the video digitizer component used by the
    sequence grabber, then call


    short theIndex = 1;
    OSType theChanType;
    ThrowIfOSStatus_(SGGetIndChannel( mSeqGrabber, theIndex, &mVideoChannel, &theChanType));
    Assert_(VideoMediaType == theChanType);

    VideoDigitizerComponent vdig = SGGetVideoDigitizerComponent(mVideoChannel);

    then you can use calls like:

    VDSetFrameRate()

    from QuickTimeComponents.h

    also, the frameworks headers declare a new bit for:

    SGSetChannelUsage(): seqGraLatencyCapture

    that you may want to set.


    What kind of digitizer are you using?
    David Guest

  3. #3

    Default Re: How to get "single field" preview with DV capture?

     

    I am using a SONY TRV60E (DV-Cam)
    markus Guest

  4. #4

    Default Re: How to get "single field" preview with DV capture?

     

    thanks for your code fragment, I am trying to aviod the fields in the DV
    input (firewire) so my program now calls:

    fError = VDSetFieldPreference(vdig,vdUseEvenField);

    but this causes error# -2202 (invalid qt parameter).
    the following call does not produce an error but this is the default
    setting and produces interlaced video:

    fError = VDSetFieldPreference(vdig,vdUseAnyField);

    I have found the tech note QTMCC12 wich reads:
    The DV decompressor in QuickTime 4 allows you to request single-field
    processing if you are decoding in high quality. This is useful to
    eliminate field aliasing when displaying still images. The parameter is
    passed in to the DV decompressor using the requestedSingleField
    parameter in the CodecDecompressParams structure.

    I am using Quicktime 6.0.3 so this must be working somehow???
    markus Guest

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