I am following a tutorial on how to work with cinelerra-cv,
in the very beginning it was said, that the very first step
in working with cinelerra, is to convert whatever video clip
one has into the dnxhd format.
It was just said, not explained how to do it.

After some research, I came across ffmpeg, but I have no idea how to use it with regard to dnxhd, with the little knowledge I gathered about ffmpeg, my guess how to do it would be:

ffmpeg -i <video-clip> -vcodec dnxhd <video-clip-in-dnxhd>

however, this does not work, and the examples I have seen on converting into dnxhd with ffmpeg I do not understand, they seemed each time having some different tags without explaining why to use them.

This is a picky encoder so you have to choose proper parameters including:

• frame rate


• pixel format / color space


• width x height / resolution / frame size


• bitrate

See the Valid DNxHD parameters below for accepted values.

DNxHD example

This example will scale to 1280x720, choose a frame rate of 30000/1001 (aka "29.97"), and a pixel format of YUV 4:2:2 planar.

ffmpeg -i input -c:v dnxhd -vf "scale=1280:720,fps=30000/1001,format=yuv422p" -b:v 110M -c:a pcm_s16le output.mov

• If your input file already conforms to some of the accepted parameters then you don't have to manually declare them.




• Output format container for DNxHD is typically MXF or MOV.

DNxHR example

DNxHR is for resolutions bigger than 1080p such as 2K, 4K, and 8K.

If you want DNxHR then add the -profile output option, such as -profile dnxhr_hq.

Accepted values are: dnxhd, dnxhr_444, dnxhr_hqx, dnxhr_hq, dnxhr_sq, dnxhr_lb.

• DNxHR LB: dnxhr_lb - Low Bandwidth. 8-bit 4:2:2 (yuv422p). Offline Quality.


• DNxHR SQ: dnxhr_sq - Standard Quality. 8-bit 4:2:2 (yuv422p). Suitable for delivery format.


• DNxHR HQ: dnxhr_hq - High Quality. 8-bit 4:2:2 (yuv422p).


• DNxHR HQX: dnxhr_hqx - High Quality. 10-bit 4:2:2 (yuv422p10le). UHD/4K Broadcast-quality delivery.


• DNxHR 444: dnxhr_444 - Finishing Quality. 10-bit 4:4:4 (yuv444p10le). Cinema-quality delivery.

The above list was adapted from DNxHR codec.

Valid DNxHD parameters

ffmpeg will fail if you provide incorrect values, but it can provide a list of what is accepted.

You can show the list with the following "dummy" command:

ffmpeg -f lavfi -i testsrc2 -c:v dnxhd -f null -

Important Notes about Frame Rate

• Frame rate is missing from the list that is generated from this command. ffmpeg will blindly accept any frame rate for this encoder, and Avid software will reportedly accept it (unconfirmed), but the DNxHD bitrate is supposed to be matched to specific frame rates only. For maximum compatibility I recommended only using the proper bitrate/frame rate combination. So use the command above to get the proper bitrates and pixel formats accepted by ffmpeg, and cross reference with the List of Avid DNxHD resolutions or the DNxHD White Paper (page 9) for the proper frame rates.



• 
  

  The frame rates listed in the links above are using inaccurate rounded approximations. The proper values are listed below; the abbreviated name is to the left and the proper value is to the right.

  
  
  
  
  
  • 29.97 = 30000/1001 (or use the alias ntsc)
  
  
  • 59.94 = 60000/1001
  
  
  • 23.967 = 24000/1001 (or use the alias ntsc-film)
  
  
  
  

More options

For additional encoder specific options, and a list of supported pixel formats, refer to:

ffmpeg -h encoder=dnxhd

Errors

ff_frame_thread_encoder_init failed

Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

Conversion failed!

This means that your frame rate, width, height, pixel format, and/or bitrate are incorrect. Refer to Valid DNxHD parameters above for accepted values.

pixel format is incompatible with DNxHD profile

Choose a proper pixel format using the format filter. See the DNxHD example above.