One of the older native codecs in Avid, the Meridien motion-JPEG (MJPEG) codec, can be read by the FFmpeg utility and, therefore, converted into other more popular codecs and wrappers. However, there is a caveat concerning the luminance levels.

Meridien MJPEG files, whether wrapped as MXF or OMF, are signalled as full-range (0 – 255) files, but in fact they contain limited range (16 – 235) data, leaving room for super-white and super-black excursions. Their pixel format is read as yuvj422p but, in conversion to the usual yuv420p used for most consumer-oriented formats, the range is reduced yet again. So, this must be prevented.

Remember also that Avid’s Meridien files contain 16 blank lines at the top for VBI information. These need to be cropped.

There is a simple solution, using FFmpeg’s scaler. For SD 576-line files (“PAL” standard), include, early in the video filter chain, this:

scale=src_range=0:dst_range=1,crop=x=0:y:16:w=720:h=576

For 480-line (“NTSC” standard) files, use this:

scale=src_range=0:dst_range=1,crop=x=0:y=16:w=720:h=480

A full command line to convert a UK television picture might be:

$ ffmpeg -i VIDEO.mxf -i AUDIO.wav -vcodec libx264 -acodec libfdk_aac -vf scale=src_range=0:dst_range=1,crop=x=0:y=16:w=720:h=576,setdar=16/9 -aspect 16:9 VIDEO-AND-AUDIO-H264.mkv