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Change Capture to Disk resolution setting v1.3.1f06



  • I'm using live capture to disk of a HD camcorder feeding HDMI 1080i through a BlackMagicDesign Shuttle Thunderbolt to a MBPr.

    I do NOT need HD video quality. I set my Live Capture source to be the "Blackmagic NTSC/PAL 8bit" so I'm not using HD resolution. Then I set the Resolution to Half Size and Quality to Low Quality.
    But I'm still running into an issue with disk size. It seems no matter what I do, the file that gets created is still using the 720*486 resolution. I tried changing the Resolution setting from Half Size to 160*120 (NTSC Quarter) and it made no difference.
    What am I missing? Or will it only save to the native resolution of the input device? And if that's the case, what is the purpose of the Resolution and Quality settings?
    Also, the compression settings don't seem to stick after relaunching the program. Should they?


  • Dear @ asavitzk,

    This is a limitation of the QuickTime (Mac) / DirectShow (Win) functions used to write the incoming video stream to disk. For highest efficiency, these systems intercept the incoming video frames at the point of capture, before any scaling or resizing has been done by Isadora.

    When you ask for a lower resolution in the Live Capture settings window, Isadora requests this from the driver. But only some drivers will actually resize the image at the driver level.

    Probably lower resolutions would work if you were using a web cam. For many web cams, when you say "please deliver my frames as 320x240" or whatever resolution you've chosen, the driver itself starts delivering frames at that resolution. But, with the Blackmagic device, it's always going to give you full resolution at the point of capture, thus changing the resolution in Isadora won't change the resolution of the Capture to DIsk actor.

    If you don't need the sound that's coming in from the camera, you might have better luck using the new Capture Stage to Disk actor. You could open a second preview stage, render the image to that, and then capture it. In this case, you'd be capturing the stage at the size indicated in the "Stage Preview Size" in the preferences.

    Best,
    Mark


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