IP camera files

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Hans Erasmus

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Jul 31, 2018, 5:19:40 AM7/31/18
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Hi all

So a while back I came across this "issue/bug". I just did not have the time to report it here, but figured out a work-around on our Opencast using ffmpeg to solve our processing issues. The problem pertains to the duration of the files created by our IP cameras i.e. camera.avi files.

The scenario: 
A video is scheduled to record for 1h20min. Our capture restarts Galicaster every morning at 06:00. Upon restarting all the feeds are initialised, as expected. Now, lets say the recording is scheduled to start at 08:00, the recording will go well and all will be as expected. However, if you then inspect the files with ffmpeg, a discrepancy in the duration of the individual files is found. See the following outputs.

ffmpeg -i camera.avi

Duration: 03:13:55.58, start: 0.000000, bitrate: 1489 kb/s

ffmpeg -i presentation.avi

Duration: 01:20:00.43, start: 0.000000, bitrate: 1960 kb/s

ffmpeg -i scound.mp3

Duration: 01:20:00.05, start: 0.000000, bitrate: 192 kb/s

The following example shows a file recorded at 12:25PM (CA was also booted at 06:00 like every morning)

ffmpeg -i camera.avi
Duration: 09:44:57.85, start: 0.000000, bitrate: 398 kb/s

ffmpeg -i presentation.avi
Duration: 01:26:00.40, start: 0.000000, bitrate: 1933 kb/s

ffmpeg -i sound.mp3
 Duration: 01:26:00.05, start: 0.000000, bitrate: 192 kb/s

Have any of you guys experienced this with IP cameras? Or is this due to the IP cameras we use? They are not high-end, but they do the job. If it is only us, I will keep our work-around in OC working, but like always, just wanna check with the rest if we are unique in this (again). I suspect this can be attributed to the rtmp feed running continuously and only recorded by GC when the schedule kicks in. I have found that the if there is a follow-up schedule, for instance 5 min after the recording stopped, the duration difference will be a lot smaller, making me think that the re-initialise process resets the counters to 00:00:00 for the rtmp feed.

Regards

Vrywaringsklousule / Disclaimer: http://www.nwu.ac.za/it/gov-man/disclaimer.html


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