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

VP9 is an open and royalty-free video codec developed by Google as a successor to VP8. It is designed to deliver high-quality video compression that rivals or even exceeds the efficiency of H.265/HEVC, making it especially popular for web streaming platforms like YouTube. VP9 supports resolutions up to 8K, variable bitrate encoding, and is optimized for reducing bandwidth consumption while maintaining visual quality, which is particularly useful for streaming over slower internet connections.

Despite its advantages, VP9 faces several challenges. One major issue is limited hardware support. Not all devices or GPUs are capable of decoding VP9 efficiently, especially older or low-end systems. This means that some users may experience playback issues, such as stuttering or increased CPU usage, when watching VP9-encoded videos. Additionally, Apple devices, including Safari and QuickTime Player, do not natively support VP9, favoring H.264 and HEVC instead. This means QuickTime can't play mp4 files on mac with VP09 encoding. This lack of broad compatibility can make VP9 inconvenient for content creators targeting a diverse audience.

Another challenge lies in software tool support and editing compatibility. Many professional video editing tools and media players either do not support VP9 or handle it poorly. This makes post-processing and playback less convenient.