[FFmpeg-user] loosing fps damaging index

[Sw@g]

Hi all,

I record a logitech pro 9000 webcam with ffmpeg, using libx264 I realise 
lately when the FPS drop the file then become corrupted and is unreadble 
after the fps drop - image is fix and the video remain at the same time.

As I use a loop to record the webcam by lapse of 10 minutes, is there a 
way to monitor the FPS and then stop and restart the command rather than 
waiting the remaining time (from the 10 minutes) ?

Alternatively, why would the FPS drops? Is there something to do to 
avoid it?

I use the following command to record the video.
ffmpeg -t 600 -f alsa -i pulse -acodec ac3 -f video4linux2 -s 960x720 -r 
15 -i /dev/video0 -vcodec mpeg4 -threads 0 cam_`date +%F_%T`.mkv

Should you require any further details, please do not hesitate to ask me,

Looking forward for your reply,

Regards,