Converts the data contained by inbuf using the formats specified by the #GstCaps passed to gstgl.glcolor_convert.GLColorConvert.setCaps
the #GstGLMemory filled #GstBuffer to convert
a converted #GstBuffer or null
Converts the data contained by inbuf using the formats specified by the #GstCaps passed to gstgl.glcolor_convert.GLColorConvert.setCaps