Heh, people got excited without even knowing the big news: g3gg0 just discovered how to use the DMA cropping routines, which just made possible RAW video recording at 1920x1080 at 24fps on 1000x cards.
Technical: we now know how to copy a cropped version of some image buffer at very high speeds (over 700MB/s), and with this trick we can save the video data the card at full speed, without being slowed down by image borders, for example.
1920x1080 RAW video now requires 83MB/s at 24fps, so it should work just fine on 1000x cards. I didn't try it.
So, I've lost my patience and rewritten the lv_rec module from scratch, to use these new routines and to experiment with different buffering algorithms. The new module is called raw_rec and outputs the same file format (RAW files).
- The ring buffer only uses 32MB memory blocks (maximum we can get). Reason: card benchmarks showed higher data rates for large buffers.
- Frame copying is done outside the LiveView task (not sure if it has any effect).
- When the buffer gets full, it skips some frames, rather than stopping.
- Fewer hardcoded things: should be easier to port.
- Resolution presets, from 640x320 to 3592x1320.
Just like lv_rec, this is in very early stages, so you have to compile it yourself.
Source code: https://bitbucket.org/hudson/magic-lantern/commits/54537cb85d7d
If you try it, I'd like you to look for any signs of image tearing. The source raw data is single-buffered, but it's possible to make it double-buffered if the vertical sync is less than ideal.
All credits go to g3gg0 - without his reverse engineering work on understanding the image processor
, this would have been impossible.