.mj video file, how to play on iPhone? - Page 1
Forum section: electronics / general

author: Jester
author_rank: Frequent Contributor
timestamp: September 06, 2023, 02:31:48 pm
content: I installed a security camera that creates .mj files on my iPhone.Looking for an app that can actually play these files, anyone?If not an app that will convert to something an iPad can play?Thanks

author: ataradov
author_rank: Super Contributor
timestamp: September 06, 2023, 02:58:43 pm
content: VLC your best bet for playing any video files. If MJ is motion-JPEG, then VLC would be able to play that. If not - then it may be impossible to tell without looking at the sample file.

author: Jester
author_rank: Frequent Contributor
timestamp: September 06, 2023, 03:42:20 pm
content: Quote from: ataradov on September 06, 2023, 02:58:43 pmThanks Alex,I think they are motion-JPEG files but not sure, VLC does not appear to work.The only thing that works (on my Win7 PC) is KMPlayer, however the ios version of KM Player does not work on my iPhone.

author: ataradov
author_rank: Super Contributor
timestamp: September 06, 2023, 03:45:01 pm
content: VLC should be able to play standard mjpeg files, so if it can't, then there is something non-standard about them.Can you share some short example file?

author: Jester
author_rank: Frequent Contributor
timestamp: September 06, 2023, 04:57:13 pm
content: Alex,Please see attached

author: ataradov
author_rank: Super Contributor
timestamp: September 06, 2023, 05:35:18 pm
content: It looks like this uses some extra wrapper or something. It does not start with a regular JPEG header and I have no idea what it is.If you remove first 92 bytes, the resulting file would start with JPEG header and VLC will display the first frame, but not the whole video, but then mplayer will stop recognizing that.And there are 33 byte inter-frame headers, so I guess this is why VLC only shows the first frame and then stops.I don't know what that header is. Usually MJPEG files are just a bunch of independent JPEGs glued together.

author: luudee
author_rank: Frequent Contributor
timestamp: September 06, 2023, 05:38:59 pm
content: Check if somebody makes an Android simulator for iPhone, then you should be able to enjoy your phone to the fullest extent ...Sorry, I couldn't help myself ....luudee

author: ataradov
author_rank: Super Contributor
timestamp: September 06, 2023, 05:43:27 pm
content: Do you really need to hijack topics with useless comments like this?

author: Jester
author_rank: Frequent Contributor
timestamp: September 06, 2023, 06:49:26 pm
content: Turns out the camera App actually has a playback mode. Daaa....I'm still trying to decipher some icons.Thanks again.

author: golden_labels
author_rank: Super Contributor
timestamp: September 06, 2023, 07:50:17 pm
content: While this will not help you with watching directly on iPhone, ffmpeg detects it as a malformed MJPEG and seems to have no trouble recoding the video. So for storage/archiving you may encode it to something digestible. MJPEG is a very inefficient format anyway.This may be a slightly damaged MJPEG to ensure vendor lock-in or lure users to install manufacturer’s app, but equally likely this may be an unintentional damage from a horribly bad implementation. The latter is not that rare.