how do I add or modify or add custom string data in an mp4?

[phibertron]

When I view an mp4 with mediainfo
Depending on what I use to encode with, I some times get different string data added to the file
for ex:

Writing Application : string
Writing Library : string
Encoding settings : string

I am currently using mencoder for my encodes, and would like to be able add what encode settings i used when the file was created

I have tried looking at mp4creator and mp4box to see how I could do this, but I havent had any success

[Brazil2]

I think you can use either YAMB (http://forum.doom9.org/showthread.php?t=115459) (a GUI for MP4Box) or MP3Tag (http://www.mp3tag.de/en/index.html) for doing such things.

[Dark Shikari]

x264 already writes the settings into the stream for you.

[LoRd_MuldeR]

x264 already writes the settings into the stream for you.

Maybe he wants to store his entire MEncoder commandline, including audio encoder settings and pre-processing filters...

[Dark Shikari]

"Encoding settings" are stored in a special H.264 NAL unit called the SEI, so it's slightly nontrivial to just cat extra data in there, and it's part of the video stream, not the container.

[phibertron]

"Encoding settings" are stored in a special H.264 NAL unit called the SEI, so it's slightly nontrivial to just cat extra data in there, and it's part of the video stream, not the container.

Ahhh, I see
But, yeah but what tool could I use to cat a string to it?

Maybe he wants to store his entire MEncoder commandline, including audio encoder settings and pre-processing filters...

Thats exactly what I want to do
Becasue a lot of times, i try different tests
and I would really love to know what the hell i did for that encode

handbrake, and x264 add the encode settings, but not the cli string i used etc.

so any help on how to add that, would mucho appreciated
Dark Shikari, has given the closest clue this far, thanks
I at least now have a starting point

do you know what searching is like on this idea
all the hits for string and mp4 dont come up with anything like this =(