Try the latest nightly with SRM memory. You should get a lot more frames. Even my slowest card (Transcend 600x) can record continuous 1568x882 and about 17 seconds at full HD (crop).
Use MLV_REC. Make sure to set picture size to raw and no jpeg (-) in the Canon menu. Switch off global draw in the mlv module and leave 'Fix Black Level' OFF (not needed). Disable the functions you don't need (i.e. don't enable vectorscope etc if you don't need it).
@Kolen - 80 mins?
How big is your card?
In the past people suggests choosing smallest JPEG but not RAW in the Canon menu. Does the newest nightly change it?
For the newest nightly (magiclantern-Nightly.2014Jul17.50D109) it seems in crop mode it gives me occasional pink frames but I am checking if it is the card issue or newest nightly issue.
I tried recording at the lowest possible settings, so it stress on the Live View and the stability of the software, and overheat but not including a huge write speed, in that case I got 80 min.
Yesterday night I tried recording at 1982X992 which is at about 80MB/s and the card heated up the sensor much quicker. But I can still record RAW video untill card full on 128GB 1050X Komputerbay, which just over 24 minutes. By the end of the recording though, there's a warning saying something like "FPS warning, overheat", etc. (wait, now I start worrying if I overheated the sensor too much so that it gives me pink frame even when it's cooled down?)
Edit: I just finished recording a video of 1568X656, full sensor 2.39:1, to fill the whole card of 128GB Komputerbay 1050X. The total duration is just below 50 min (by pressing ISO button to reset timer). And the sensor has overheat warning by the end of it.
Edit: I tried it on an older build and it doesn't seem to have the pink frame. However I only recorded a few minutes.
I guess it is the newest nightly that cause the issue. How do I report the bug (after I have more testing)?
Thanks.
Edit: I nailed down the builds that cause the pink frame problem:
Nightly.2014Jul17.50D109 and magiclantern-Nightly.2014Jul16.50D109 2nd build.
Using earlier build doesn't seem to have the same problem. e.g. magiclantern-Nightly.2014Jul16.50D109 1st build, magiclantern-Nightly.2014Jul15.50D109
The condition is, I use RAW_REC, Expo. Override, Global Draw off, FPS 23.976 exact, RAW Video at 1984X992 in crop mode. Shutter 179 degree, ISO 800, lens with no electronic contact, etc.
And the pink frame will show up quite frequently, and can be seen even in live view.