创建具有Alpha通道/透明度的视频文件

Question

I'm experimenting with a video file with alpha channel. Later on the file should be an overlay for another video. It will be merged with another file in real time and saved to another file. But that is not the important point. The problem starts earlier because I can't even play it.

The video is a png-encoded Quicktime-file which I cannot play with any video player. WMP, VLC, MPC and ffplay all show various problems which all lead to the problem that the images seem to get decoded too slowly. The strange thing is that neither cpu (i7) nor my ssd are on limit but the file isn't played correctly.

Since the problem appears with all players I think it's based on using png in video. I googled but didn't find a proper way to create a partly transparent video file. I tried various methods of exporting (with adobe media encoder) with no result: the file lost its transparency or is running too slow.

The resulting file which I create with my SDK is correct (video and audio are synchronous and fluid) but it takes 1 minute to render a video of 40 seconds although it works in real time with files without transparency.

Does anyone know what kind of file I should export that has a minimum resolution of 720p, that is partly transparent and that can be played with ffplay in real time? I would also appreciate any experiences with partly transparent videos which could help me because I couldn't find any helpful links?

Thanks, Marius

Answer 1

The real solution to this problem is to always export a Quicktime file that makes use of the lossless Animation codec. This can either be 24BPP (Million) or 32BPP (Millions+) with a full alpha channel, but the main point is that the codec is lossless and should be playable on different desktop computers.