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  1. #1
    Nokia Developer Champion
    Join Date
    Mar 2013
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    517

    Video Preview Resolution / Frame Grabs in Full HD

    I'm working in my new App with the manipulation of Image data live captured from the Camera's video stream. On my Lumia 920 the maximum Preview Resolution that is supported is 1280x720 (720p). The Camera can do 1080p (FullHD) capture so I wanted to know if there is any way for me to get live access to frames of that size?

    I'm currently using the audiovideocapturedevice.GetPreviewBufferArgb method to acquire the image data which is further manipulated before being inserted into a WritableBitmap for display later on. My biggest fear is that the lowered preview resolution could mean that I'll not be able to even get access to 720p frames on devices with lower screen resolutions like the Lumia 720/620/520 which would severly limit the usefulness of my App on those devices.

  2. #2
    Nokia Developer Moderator
    Join Date
    Feb 2006
    Location
    Oslo, Norway
    Posts
    28,737

    Re: Video Preview Resolution / Frame Grabs in Full HD

    I have no idea about the Lumia 920, but generally speaking devices having high-resolution imaging/video features tend to do the compression as early as they can, using hardware support if available. Full HD images are around 6 megabytes uncompressed, and at 25 FPS it means around 150 megabytes per second. It is also considered normal that maximum camera preview resolution is somewhere around the screen resolution, so there are chances that other devices will get lower resolution preview.

  3. #3
    Nokia Developer Champion
    Join Date
    Mar 2013
    Posts
    517

    Re: Video Preview Resolution / Frame Grabs in Full HD

    I'm only grabbing a frame every 150 ms or so but even then I have to use the Video stream because the Camera is not able to take photos in that fast a succession (at least in my tests). I'm also only taking 11 pictures overall so the memory footprint should be acceptable. Theoretically it would be sufficient if I could capture the video and extract frames at those positions but I don't know if I can properly (quality wise) extract frames from a recorded video or how to extract frames from a recorded video at all on WP8.

    My biggest problem in the end is that I might not be able to capture at least 720p on lower end devices although being able to capture the full size 1080p frames would be of benefit as well. Guess I'll have to find out how well it works with a Marketplace Beta. Thank you for the input anyway.

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