VP8 specific options

vp8_quality

This sets the quality parameter for libvpx. The default value is good. The options are:

Quality Description
realtime Fastest encoding, but less quality
good Default encoding
best Very slow encoding but better quality

vp8_yuv420p

This forces it to translate the video to YUV420 before encoding, this is required for most video players so it is true by default.

vp8_crf

This sets the constant rate factor. The CRF controls the output quality. The range is 4-63.

The default value is 10