Summary: MP4 is the widely used file format supported by almost all devices and media players. Check the detailed free MP4 converters for Mac review that will lead you to AVI/MKV/YouTube to MP4 converting and MP4 decoding for your purpose.
Why are you going nuts? You download video in MKV format and plan to watch MKV files on your MacBook Pro with Retina display. But your QuickTime player informs you that it can't handle MKV files. You're disposed to play AVI on your iPhone when on the trip or way back home. Yet, iTunes doesn't allow you to add AVI to iTunes, let alone to iPhone. You extract music from MP4 to MP3 for music player, yet the output audio quality is extremely garbled. So you have no choice but to resort to a free MP4 converter for Mac. But some free MP4 converter Mac software drives you insane with varied problems like poor output quality, irremovable watermarks, endless 'demux' 'remux', etc. To help you out of such troubles, this post covers all sides about video conversion to MP4, read the specific solution you need:
Repair Damaged MPEG4 Video File on Mac Use Remo Repair MOV tool to repair corrupt MPEG4 video file easily on Mac. It can repair MPEG4 videos that are broken, truncated, unplayable or inaccessible.