Fixing potential motion blur with HiLook PTZ

[shivampaw]

Hi

We’ve got a HiLook PTZ camera to record some sports (cricket) and it’s working well network wise but the issue we’ve got is there sometimes seems to be what I think is motion blur around graas areas causing it to look a bit like the ground skips frames and changes colour. I’ve attached video.

Is there a way to make it smoother?

It’s at 15fps with an i frame interval of 15. The exposure for the video attached was set to Auto with Max shutter limit of 1/25. I’ve changed that to 1/2500 with a Limit Gain of 15 and the light seems okay but I’m not sure if that’ll help with the ground issues which seem to happen when there’s more movement in frame.

Thank you!

 

[trempa92]

Change from variable bitrate to constant and give it a value that u deem good.

 

[alastairstevenson]

there sometimes seems to be what I think is motion blur around graas areas causing it to look a bit like the ground skips frames and changes colour.

What you are seeing in the video is the consequence of how H.264 / h.265 video compression works in IP cameras.
The 'pulsing' occurs when the timed 'i-frame' frame refresh is sent in the video stream. Check the i-frame settings in the camera web GUI and you'll see how many intermediate frames are configured - I'd guess from your video that i-frame is set to 15 as your fps is 15, giving the once per second full refresh.
edit I now notice you'd already mentioned that.

The way h.264 works is that successive frames holding only changed data are sent until the i-frame interval when a full frame is sent. The cycle repeats.
This full frame refresh is often quite visible on uniform parts of a scene.
Not a great problem for a surveillance camera - not so good for a sporting scene.

The refresh is more obvious if the camera is set to use a low bitrate - ie higher compression - making the refresh more obvious.
Try upping the bitrate as much as you can.
And, as suggested by @trempa92 above, use CBR versus VBR for best results.

 

[alastairstevenson]

I’ve attached video.

alastair@PC-I5 ~/tmp $ mediainfo 1_*.mp4
General
Complete name                            : 1_042_02.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/avc1/mp41)
File size                                : 9.10 MiB
Duration                                 : 36 s 200 ms
Overall bit rate mode                    : Variable
Overall bit rate                         : 2 109 kb/s
Writing application                      : Lavf58.76.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline@L3.1
Format settings                          : 2 Ref Frames
Format settings, CABAC                   : No
Format settings, Reference frames        : 2 frames
Format settings, GOP                     : M=1, N=30
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 36 s 200 ms
Bit rate                                 : 2 103 kb/s
Width                                    : 854 pixels
Height                                   : 480 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 15.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.342
Stream size                              : 9.07 MiB (100%)
Codec configuration box                  : avcC

Audio
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 36 s 200 ms
Source duration                          : 36 s 221 ms
Source_Duration_LastFrame                : -3 ms
Bit rate mode                            : Variable
Bit rate                                 : 2 277 b/s
Maximum bit rate                         : 128 kb/s / 128 kb/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 10.1 KiB (0%)
Source stream size                       : 10.1 KiB (0%)
Default                                  : Yes
Alternate group                          : 1
mdhd_Duration                            : 36200


alastair@PC-I5 ~/tmp $

 

[shivampaw]

Thanks both! I’ve set it to a constant bitrate of 2560 with 1280x720p and 15fps. It seems better, does that seem a reasonable bit rate?

Thanks again!

 

[alastairstevenson]

I’ve set it to a constant bitrate of 2560 with 1280x720p and 15fps. It seems better, does that seem a reasonable bit rate?

I'd bump it up some more to see if there is further improvement. Then you'll know where the optimum setting is.