2018-06-14 23:03 GMT+02:00, Mark Schafer <[email protected]>: > We're trying to integrate ffmpeg 4 with Pyglet. > Its all going very well but we have one issue: > > - If a VP9 (or VP8) file is created using ffmpeg4 from png files with > alphas, we get a video file (webm) with alpha internally. (Excellent) > - ffmpeg -i image_seq%03d.png -qmin 0 -qmax 50 -crf 5 -b:v 1M output.webm > - The report from this CLI indicates that an alpha has been generated. > > - Sample webm videos with alpha can be found on this page: > https://simpl.info/videoalpha/ > - However on playing back we only get the RGB and do not get the alpha > unless we override the codec to be 'libvpx'.
Yes, this is a known limitation of the native decoder, luckily you have already found the only known work-around - not to use it if you need this feature. If you really want to choose the decoder based on the alpha layer, you can check AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL if the side_data starts with (uint64_t) 1 there is a transparency layer. It is probably simpler to always use the libvpx decoder. Carl Eugen _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
