Convert ABR to MP4

To our knowledge, converting any existing ABR file types directly to MPEG-4 Videos (.abr to .mp4 conversion) is not possible.

Should this, however, be a typo, and you were in fact searching for ways to convert Adaptive Multi-Rate Codec Files to MPEG-4 Videos, please check out the AMR to MP4 conversion entry.

In a word, direct abr to mp4 conversion is not possible.
So don't expect any so-called abr to mp4 converter or abr to mp4 free online conversion tool available.