FPS and bitrate
- Thread starter lacibaci
- Start date
I would experiment a little and see if you see any difference between 8194 & 6144 bitrate. 10fps may work well for you, if it seems a little choppy you could try 15fps. 15fps seems to be a favorite of a lot of people on this forum.
DemonicHawk
Young grasshopper
See page 2 of this pdf: http://www.hikvision.msk.ru/_fr/0/IP_Camera_Recom.pdf
Ok, looking at that, if I choose 8fps, the default bit rate (4096bps) should be plenty. Does that seem right?
Michelin Man
Getting the hang of it
I reckon if you're going to set the max bitrate that high you might as well increase the framerate. 10fps I reckon is a bit too low for my liking, I personally wouldn't run less than 20fps but that is my opinion (for cameras that can do 20fps at the respective resolution).
DemonicHawk
Young grasshopper
Yep, so 8192kbps at 10fps would be overkill in my opinion. BUT, if you're looking to really maximize image quality, there are definitely some small benefits to increasing the bitrate even further. I've played around with the bitrates myself and the "Best" bitrate isn't "Absolute Best". Alternatively you could just set a ROI to compensate.
I agree as I run mine at 20fps as well, but there are a lot of practical reasons for having a lower fps such as higher image quality or lower storage requirements. Really just depends on the use case.
Michelin Man
Getting the hang of it
Ohh of course. In this case the OP didn't seem to have too many cameras or space restrictions, especially if the set bitrate was 8192kbps.
If OP needed heaps more storage for a given space then by all means. Although In that case I'd probably turn down the max bitrate a bit, and set a higher framerate. IMO, the more frames you have the better. Especially if you need it to ID someone.
- - - Updated - - -
I believe you are supposed to match IFrame to FPS. Otherwise that happens.
If you set the iframe interval at the same fps as the video frame rate, then you will notice the flashing (I would call it judder) every one second and therefore it is visible. If you set the iframe interval at 100 and the video frame rate at 20 then you will notice (very difficult) the judder every 5 seconds. In this case it will not be very much visible but only because our brain "forgets" easily what has happened 5 seconds before. The truth is that at every x frames defined as the iframe rate, the camera cpu generates and stores the iframe which the full image frame and it has the largest size (in bytes) compared with the rest (intermediate) frames. All other intermediate frames are only the differences compared to the last iframe image and therefore occupy less bytes. The generation of the iframe takes more processing time and cpu load compared to the rest of the frames and require more storage space. Therefore the more frequently the iframe is generated the more the camera cpu processing is loaded. The advantage of having more frequent iframes is the speed of decoding the video stream during playback. If you set the iframe every 20fps and the video frame rate at 20fps, then the cpu needs to decode 20 frames before displaying a video stream of 1 second. If you set the iframe at 100 fps and the video frate rate at 20 fps, then the cpu must decode 100frames before it starts to stream the 5 seconds video stream, therefore the starting of the video stream delays and the cpu may be loaded more during playback. It also depends on how fast the hard diskcan provide the data stream to the cpu.
Therefore the selection of the iframe rate is a combination of the cpu camera abilities, the NVR decoding capability and therefore the number of cameras decoded at the same time and the ability of the hard disks to provide the data stream of the cameras decoded for viewing.
If you do not mind the judder or flashing, then let the iframe equal the video framerate.
Therefore the selection of the iframe rate is a combination of the cpu camera abilities, the NVR decoding capability and therefore the number of cameras decoded at the same time and the ability of the hard disks to provide the data stream of the cameras decoded for viewing.
If you do not mind the judder or flashing, then let the iframe equal the video framerate.
My old settings were 4fps/4iframe at 4096bps. The quality was OK (no pulsating/judder) but I wanted a little more fps. After setting it to 8fps/8iframe I can see the judder. No matter what I set the fps/iframe, there is always some judder.
The only way I was able to get rid of it was setting the bitrate to the highest value.
The only way I was able to get rid of it was setting the bitrate to the highest value.
DemonicHawk
Young grasshopper
What firmware are you using? On my 2CD2032s, the 5.3 firmware had noticeably more pulsating than 5.2.x firmwares.
Michelin Man
Getting the hang of it
The thing about the I-Frame is interesting.
For those that don't know what an I-Frame is here is a good explanation:
http://www.slingbox.com/en-US/Support/KB/KB-2000081.aspx
Also, more discussion on I-Frame here on Cam-It.
http://www.cam-it.org/index.php?topic=6328.0
as well as on cctv forum
http://www.cctvforum.com/viewtopic.php?f=19&t=39362
So basically you sorta want more I-Frames, but you need to set a higher max bitrate to accommodate. Again every situatin is different so see what works best for you.
For those that don't know what an I-Frame is here is a good explanation:
http://www.slingbox.com/en-US/Support/KB/KB-2000081.aspx
Also, more discussion on I-Frame here on Cam-It.
http://www.cam-it.org/index.php?topic=6328.0
as well as on cctv forum
http://www.cctvforum.com/viewtopic.php?f=19&t=39362
So basically you sorta want more I-Frames, but you need to set a higher max bitrate to accommodate. Again every situatin is different so see what works best for you.