my macbook air won't play mp4
my macbook air won't play an mp4 file. says it's incompatible?
MacBook Air 13″, macOS 11.5
...about the codecs:
There is the "old" H.264 (AVC Advanced Video Coding) and new H.265 (High Efficiency Video Coding HEVC) that needs macOS 10.13 High Sierra or later.
QuickTime Player refuses to play some H.265/HEVC flavors. Currently macOS 11-13 Big Sur, Monterey and Ventura are more forgiving but they still has the following issues with "Codec ID" and "Chroma subsampling" options.
You can check all those pesky details with apps like Invisor (my favorite because it neatly highlights differences when a folder is dropped on it) or MediaInfo.
H.265 Codec ID hvc1 plays OK.
H.265 Codec ID hev1 has an error message "This file contains some media that isn't compatible with QuickTime Player" and plays audio only. There is a lossless fix if you install ffmpeg and add '-tag:v hvc1' without re-encoding in the Terminal:
ffmpeg -i input.mp4 -c copy -tag:v hvc1 output.mp4
Chroma subsampling 4:2:0 (Bit depth 8 bits) plays OK.
Chroma subsampling 4:2:2 (Bit depth 10 bits) has an error message "This file contains media which isn't compatible with QuickTime Player". It fails in Mojave, opens anyway in Big Sur, no problem in Ventura.
Usually H.264 Codec ID avc1 is OK. But DJI Mavic3 5k H264 10Bit420 does not open, and Sony XAVC-S (H264) 10-bit displays only black frame.
Google, Youtube, Facebook might use VP8 or VP9 video and OPUS audio codecs that have to be converted to more common H.264/265 and AAC/PCM codecs. macOS 14 Sonoma added support OPUS audio.
VLC and IINA should have no issues with playing any decent new or old codec. Handbrake, VLC and ffmpeg can be used to convert old codecs to new H.264 or H.265 wrapped as common mp4 (or its very close cousin m4v or mov). ffmpeg can output also ProRes.