Loop image over audio, as AvidDV codec with ffMPEG
deprecated pixel format used

This is a warning, not an error, and you can ignore it.

DNxHD

The FFmpeg DNxHD encoder only supports valid DNxHD profiles. ffmpeg will output the list if you attempt to output unsupported width x height, frame rate, bitrate, and/or pixel format. Or view the list at another answer.

DV

FFmpeg can output DV, but I'm not quite sure why you would want to. This is an old format and there are better, modern, lossless alternative intermediate formats for editing such as UT video (ffmpeg can encode and decode that too). Like DNxHD it will only output certain DV profiles, but it can use the -target option to make it arguably easier to use:

ffmpeg -i input -target ntsc-dv output.dv