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Live HD projection controller feasibility questions.

  • DJonsson

    I'm exploring Snowmix as a framework to use an Ubuntu
    workstation as a video mixer for live projections.

    I've watched some of the Snowmix Youtube videos, and have read the online
    wiki. I understand this is a set of tools, that requires some configuring
    and testing to get going. That is O.K. as am looking for a framework of
    sorts. Before diving into this though need to check with this discussion
    if our goals are feasible with Snowmix...

    Here are our goals.

    • Input : 3 Feeds (HD 1080p Video mpeg4 or avi files & JPEG stills also HD 16:9 1080 format)
    • Output : to HD 1080 projector.
    • Hardware : 1 Ubuntu workstation with monitor (for control panel)
      connected to projector via HDMI.
    • Capacity to dim feed and switch video source files per channel while in production.

    Other features we are looking for.

    Easy togggle/transition for the following.

    • Single screen display, with dissolves and mix between 3 feeds.

    • Split screen display of 2 feeds. diapyct

    • Split screen display of 3 feeds. tryptych

    • No audio mixing needed.

    _Is the above within the scope of Snowmix?
    _Is the Gui Mixer used with Snowmix capable of the above?
    _Is Ubuntu 12 our best best for appropriate libraries and versioning?

    Please advise - D. Jonsson

  • Hi.

    Sorry for being late in answering. Been away on vacation to low bandwidth land.

    Snowmix is specifically well suited for the tasks you mention and it was designed with such tasks in mind.

    Snowmix can take any geometry and aspect ratio, so 1080p/1080HD and 16:9 is easy. Snowmix can take any number of input feed up to possible 2^32. Snowmix uses GStreamer module shmsink for inputting video live or recorded. You can input still images as a video feed as well, but you can also convert images to PNGs with an alpha channel using GIMP and preload these images. In most contexts displaying an image or a video feed is identical for Snowmix and as such interchangeable. Preloading images when possible has the advantage that Snowmix does not risk stalling while waiting for the harddisk to spin up.

    You output from Snowmix using the GStreamer module shmsrc. Displaying on the same machine as you run Snowmix has the advantage that you don't have to encode the output stream possible saving up to half the CPU required for your overall system.

    Snowmix was developed on a Ubuntu workstation. You will want to use a multi core hardware even though Snowmix is mostly, but not entirely single threaded. The extra cores come in good use when you run several GStreamer input pipelines. Decoding and converting video streams from perhaps h.264 to RGBA using GStreamer pipelines is well suited for multi core systems and will usually use more CPU than Snowmix in it self.

    Dimming/fading video feeds and images as well as switching between them is easy and Snowmix supports commands for linear animation of alpha, scale, rotation and placement. Non-lnear animation can be achieved using either external programs talking to Snowmix or by using the embedded tcl interpreter. The demo application Snowcub.tcl uses both methods.

    Snowmix can easily be setup to switch/fade between 3 feeds and also display 2 or or more feeds simultanously. Run the demo script and try out the sapphire testcase using Scenes and snowcub.tcl.

    You can setup any split screen scenario you can think of.

    Mixing audio is not required, just an option offered.

    Snowcub.tcl can be used as a GUI for the listed requirements. Please note that Snowcub.tcl reads the configuration from a running Snowmix session and crate its GUI from that information. Snowcub.tcl is not created to configure Snowmix.

    Snowmix up until 0.4.3 was developed on Ubuntu 12.04 LTS Workstation. The next version 0.4.4 is tested with any Ubuntu 12.04-14.04 as well as Fedora, Debian and OS X.

    Best regards
    Peter Maersk-Moller



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