Why quicktime not playing mp4 files on mac and windows pc?

If QuickTime not playing MP4 files on your Mac or Windows PC and you're looking for a free solution, here are some steps and alternative options you can try:

What should you if Quicktime not playing MP4:

• Update QuickTime: Ensure you have the latest version of QuickTime installed (For Mac).
• Check the MP4 Codec: Sometimes, QuickTime may not support certain codecs inside MP4 files. You can verify this with a media info tool like MediaInfo (For Mac).
• Update QuickTime: If you still want to troubleshoot QuickTime, ensure it’s up-to-date (for Windows computer).

1. Use Built-in Media Players (Windows & Mac)
Windows: The default Movies & TV app or Windows Media Player can often handle MP4 files. 
Mac: The default QuickLook or Preview might open some MP4 files, but if not, try other free players.

2. Use Free Open-Source Media Players
MPV Player: A lightweight, open-source media player that supports a wide range of formats.

3. Convert MP4 Files to a Compatible Format
Use HandBrake (free) to convert your MP4 to a format compatible with QuickTime.
* Download from HandBrake
* Open HandBrake, load your MP4, select a compatible format (like MOV or MP4 with supported codecs), and convert.

4. Check and Repair the MP4 File
Sometimes, MP4 files are corrupted or have incompatible codecs.
* Use MediaInfo to check the codecs used.
* If the file is damaged, try repairing with tools like FFmpag (free, command-line) or online repair services.