So, a funny thing happened. While doing some additional testing, the sound recording started working out of nowhere, as it seems. I did have some issues and I did get one Err70 out of all my extra tests and it was the strangest one yet.
Mar07 Build
mlv_lite + mlv_snd + sd_uhs
1832x1024, 14-bit lossless, 16:9
Preview: Realtime
Small hacks: ON
Auto Mirroring: Don't allow
15 min. - Video OK, sound OK, NO ERRORS!
Additionally tested later:
45 min. - Video OK, sound OK, NO ERRORS!
50 min. at ISO200 - Video OK, sound OK, NO ERRORS!
47 min. at ISO400 - Video OK, sound OK, NO ERRORS!
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mlv_rec + mlv_snd + sd_uhs
1824x1026, 10bpp, 16:9
Global Draw: Allow
15 min. - Video OK, sound OK, NO ERRORS!
Additionally tested later:
15 min. - Video OK, sound OK, NO ERRORS!
The mlv_snd module was loaded and turned on, but the sound meter bars didn't show up.
Mar14 Build
mlv_rec + mlv_snd
1792x716, 10bpp, 2.50:1
Global Draw: Allow
15 min. - Video OK, sound OK, but Err70
When I pressed stop at the 15th minute, the recording timer froze, the top display said "Busy" and a few seconds later.. guess what.. Err70! Had to take out my battery this time. The MLV file had sound, though.
mlv_lite + mlv_snd
1600x900, 14-bit lossless, 16:9
Preview: Realtime
Small hacks: ON
Auto Mirroring: Don't allow
15 min. - Video OK, sound OK, NO ERRORS!
Everything went as normal: audio meter bars showing up and working, camera reacting normally, when starting and stopping recording. I should mention, that I tried recording in 1776x1000 with everything alse the same, but the camera stopped after a couple of minutes. It stopped in a normal manner, like when the resolution is just too high - no unusual errors. When I tested that build before, with the higher resolution, it worked for 40 mins., but now with mlv_snd also loaded, it looks like it can't keep up.
Doesn't make much sense to me. In all tests I kept ML at default settings with only the modules, mentioned above loaded. I don't think Canon's menu settings have an effect on RAW recording, but most were kept at defaults (incl. audio), except: image recording set to RAW only, video recording format set to 24fps, IPB, colour profile set to Faithful (from Auto), Beeping turned off. Can't think of anything else. The way I switched from build to build for testing, was without uninstalling ML, just deleting one build's files from the card and copying the other build's onto it. I have both builds with my settings backed up in folders.
I'll keep testing. If anyone has any insight, please share.