Philippe Gorley authored Aug 12, 2019 and Adrien Béraud committed Aug 12, 2019

Hardware decoders output nv12, but Jami's software encoders want
yuv420p. If using a hardware decoder, make sure the input frames are
yuv420p. If using a hardware encoder, keep the frames as nv12.

Change-Id: I5b20238786104da4ddf25bee061899be18fa0d59