MI2 Slow Motion Video Capture


Oct 5, 2011
2
4
13
#1
Hello, i bought a MI 2 device recently, and i have a problem with slow motion video captue.

I've selected 90 fps in settings and enabled "Fast" mode in camera interface. The recording process went ok, the actual output file is three times longer than the recording time, as expected, but has playback fps of ~10 (as reported by VLC and MediaInfo).

Similar thread with no solution – http://miuiandroid.com/community/threads/camera-issues.19540/ (with example videos)
I apologize for making another thread about the issue, but the old one is outdated and the problem is poorly described in the 1st post.

I tried JLB14, 3.4.12, 3.4.19 roms, but the issue remains.
There are lots of smooth videos filmed with Xiaomi Mi2 (~30fps as reported by MediaInfo), some of them are also recorded on 3.4.19.
I'm not satisfied with my phone's result (planned to try some computer vision magic with high fps).

I recorded some logcats (on 3.4.19) and it seems that the buffer/encoder is the issue. For example:
Code:
E/OMX-VENC-720p(  170): ERROR: Unsupported H.264 level= 1105119184
E/OMX-VENC-720p(  170):  ERROR: unsigned int venc_dev::venc_start()(): Driver Profile/Level is NOT SET
W/OMXCodec(  170): Failed to set frame packing format on component
More detailed logcats are attached.
The issue also presents in 480p + fast mode, but there is nothing about H.264 levels in the log, only "frame packing format" error.

Also, strange observation about camera: In FullHD video capture the output file has 1920x1088 resolution.

Can anyone provide any further information about the problem? Thanks!
 

Attachments

Oct 5, 2011
2
4
13
#2
Further research showed that there is no problem with the camera or encoder. The actual problem was with the lighting conditions.
When filming with insufficient light, the camera increases exposure time for each frame to make image more bright and clear. As soon as the exposure time exceeds 1/90 sec, filming in 90fps becomes physically impossible. If you force the camera to reduce the exposure time somehow – filming in 90 fps with insufficient light will be possible, but the image quality will suffer greatly.

So, if you're not satisfied with frame rate your device provides in slow motion videos - improve lighting conditions.