Workaround NPOT buffers when using hardware acceleration
I currently get this error when running a program with a NPOT framebuffer and --hwvideo:
S7238: 48.940234 [src/video.c:664] Video dimensions (WxH = 1366x768) not alignable to use hardware video encoding
A possible workaround would be to use a ffmpeg filter to add (black?) borders to complete the buffer, encode that, and remove the borders on the decoding side.