Why the compression?
  • brendanrbercik
    junior Member
    Posts: 8
    Joined: Tue Nov 08, 2016 12:53 am

    Why the compression?

    by brendanrbercik » Tue Dec 05, 2017 9:19 pm

    Hey all, I'm having fun getting to work with my new miniMAD (my first). It's perfect for this gig, a lovely little compact media player-as-standalone solution.

    I'm just curious –– why must the video be compressed so heavily? The video quality would be my one gripe with the miniMAD's performance. Do all Raspberry Pi-based players require H.264 or something? Even when choosing the "0" option, which is stated as "lossless," there is a noticeable quality drop from my original video.

    Are there any suggestions for encoding my video before exporting to miniMAD, so that I have as much control as possible, and the miniMAD makes as few adjustments as possible?
  • Pierre Guilluy
    garageCube team
    Posts: 258
    Joined: Mon Oct 12, 2015 1:50 pm

    Re: Why the compression?

    by Pierre Guilluy » Wed Dec 06, 2017 3:23 pm

    The Raspberry Pi (which miniMAD is based upon) supports H264 hardware decoding with a very specific pixel format (420p) so most of the time transcoding (compressing) is required when exporting to the miniMAD.

    Then, depending on the resolution and framerate of the original video-file, the part of it that will actually be mapped, and the selected projector resolution, MadMapper will crop and downscale the original file while transcoding to guaranty a smooth playback on the minMAD that has limited computing power, especially when using the graphics adapter for live video-mapping and color management as we do.

    There are a few advanced options that are available for tweaking the transcoding and get better results for a specific content.
    But if you feel like so, you can transcode your files with your favorite video-file-encoder and place the results in the mapping/ folder of the miniMAD. Just keep in mind the file has to be H264 / 420p encoded to be played by the miniMAD.
  • brendanrbercik
    junior Member
    Posts: 8
    Joined: Tue Nov 08, 2016 12:53 am

    Re: Why the compression?

    by brendanrbercik » Thu Dec 07, 2017 1:14 am

    Thank you for the thorough answer, and suggestions...but yikes! 420p! Well, you live and you learn.
  • Pierre Guilluy
    garageCube team
    Posts: 258
    Joined: Mon Oct 12, 2015 1:50 pm

    Re: Why the compression?

    by Pierre Guilluy » Thu Dec 07, 2017 10:44 am

    420p suggest you're using more than the usual 25/30 fps, isn't it?
  • brendanrbercik
    junior Member
    Posts: 8
    Joined: Tue Nov 08, 2016 12:53 am

    Re: Why the compression?

    by brendanrbercik » Thu Dec 07, 2017 7:16 pm

    420p suggest you're using more than the usual 25/30 fps, isn't it?
    The video is 30fps. If I exported at 25 would it remain at 1080p?
  • Pierre Guilluy
    garageCube team
    Posts: 258
    Joined: Mon Oct 12, 2015 1:50 pm

    Re: Why the compression?

    by Pierre Guilluy » Wed Dec 20, 2017 5:57 pm

    Yes, using a lower framerate should increase the resolution.
    You can send me the original file in a PM so I can analyze it.

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