Transparency Apparently
BlitzMax Forums/BlitzMax Programming/Transparency Apparently
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| I don't think this is a beginner's question so I am posing it here. What could be written in BlitzMAX to do two things ? [1] Display a movie, an Mp4, at a fixed size and location on the screen. [2] The ability to plot to that screen in BlitzMAX where color R=0, G=0, B=0, bleeds through the video, and any other colors appear as pixels on top. I'd like to do this so I can build an animated watermark and slider marquee in front of the video. |
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| 1) IIRC there's some code that uses the VLC playback libraries to draw video to the screen, which should be able to handle .mp4. (What platform are you talking about here? Windows, Linux, Mac?) 2) Not sure what you mean here, but you can draw whatever you want on top of video, simply by not erasing the background but giving additional drawing statements before the flip. |
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| I know you can display a video in BlitzMAX, Xlsior. what would be unique is to plot directly above that movie surface in BlitzMAX keeping in mind any non-plotted pixels are transparent and would show the video beneath. BlitzMAX code of this design would be interesting and likely helpful for others to see and make use of. For instance, you could play a video from Online and inject SRT directly into it - or inject your own special effects into an Offline video you record and then can re-record with the new effects generated from BlitzMAX, the main reason I would want it. |
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| With Brucey's AVBin module I was able to get each frame of a video as a Pixmap, which I could manipulate any way I wanted. But AVBin seems to be very outdated now. |
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| When you install the VLC media player you can get the libvlc and libvlccore DLLs to use with this: http://www.blitzbasic.com/codearcs/codearcs.php?code=3230 Using that code archive as example, you would supply a function pointer to the "unlock" callback of libvlc to do processing, such as converting the decoded pixels of the video frame to a BlitzMax TPixmap. https://www.videolan.org/developers/vlc/doc/doxygen/html/group__libvlc__media__player.html#gadb157d29493dfc0f89d889603e76aeb9 |
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| I know you can display a video in BlitzMAX, Xlsior. what would be unique is to plot directly above that movie surface in BlitzMAX keeping in mind any non-plotted pixels are transparent and would show the video beneath. What do you mean "plot directly above that movie surface"? Typically, you open a graphics screen or a canvas. you draw the movie frame. As long as you don't FLIP to make the updated screen visible yet, ANY other drawing operations (whether images, lines/pixels/whatever primitives etc.) you draw afterwards before the flip get drawn on top of the movie, and any place where you don't draw you still see the movie. That's it. the video framr would be drawn just like any other image that's part of a scene. Unless you mean something entirely different, I don't really understand what the problem is here... |
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| Hi Xlsior: Here is an example of what I would like to do in BlitzMAX: Display and animate a movie. While the movie plays I can draw circles, lines, raster, and text directly on top of the movie screen.  Where "JORDAN DURAM" is plotted by Blitzmax's own DrawText() routine. It will stay there displayed until you clear the pixels, say with Cls(), which will NOT clear the video frame, just what is plotted on top of it. |
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| It will stay there displayed until you clear the pixels, say with Cls(), which will NOT clear the video frame, just what is plotted on top of it. No way around it -- You will need to redraw the video frame after each and every flip, then draw your own stuff on top of it again. Both the DirectX and openGL specs say that background buffer is undefined after you do a flip, so there is NO guarantee that the background remains... And even on the computers where the videocard does retain the previous frame, it would have everything including the other stuff you already drew, which you apparently don't want. On some card it would be black, and on other cards it may rewind one, two, three, or even four frames depending on how many backbuffers the videocard drivers use and cycle through internally. As far as (re)drawing the videoframe: Here's a snippet from Grable that takes the frame as a pixmap or image with the VLC libraries, which would be trivial to redraw: http://www.blitzbasic.com/codearcs/codearcs.php?code=3230#comments |
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| Ah that's too bad, Xlsior. That would've been a nice and easy way to introduce special effects and information into an already coded or streaming video. |
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| You do zero research and then give up. The next time you're wondering why you don't grow in your field, please remember this moment. |
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| That would've been a nice and easy way to introduce special effects and information into an already coded or streaming video I fail to see how a single "draw the video frame!" call before drawing your own stuff on top of it is apparently such a problem. |
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