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Dec 25, 2018

Compression artifacts at 1080p

16 comments

Hi all,

 

after my first trip with the K2 installed, I am a little bit disappointed about the video quality because of compression artifacts.

When the area beside the road is clear (e.g. open fields), everything looks nice and clear in the video. But as soon as there are more objects (e.g. much trees with leafless branches) the video gets blurry in some areas. Below are some examples.

 

For me it seems, that the bitrate isn't high enough to compress/save all the details.

The vidos of my K2 are recorded with a bitrate of max 12000 kbps, while the videos of a friend of mine are recorded at up to 24000 kbps (using a Sony ActionCam).

 

My SD-Card is a SanDisk 32GB HC I (UHS Class 1)

Firmware of K2: K2.20180925.V0.39

 

Examples

Its hard to see at that resolution here in the forum. You need to see it at full screen. Watch the lower right side of the road and the number plate of the incoming car.

Recorded at 60 km/h.

ArtifactsArtifacts

 

 

In comparison this picture without artifacts, recorded only some seconds later. Same road, same speed. Everything looks fine. You can see every detail of the road.

No ArtifactsNo Artifacts

 

 

Another example. Again hard to see at that resolution. You need so see it at full screen.

The roadside at the lower left and right corner looks blurry. Recorded at 30 km/h.

 

And in comparison the same road without artifacts, some seconds later

Everything looks fine and the roadside is very detailed. You can nearly count the grasses.

 

Any suggestions what I can do against those artifacts?

 

I tried to check whether the K2 does a better job in 720p or not, but I cannot change the resolution (see other topic)

 

Regards,

 

Frostie

 

Dec 26, 2018

 

For me it seems, that the bitrate isn't high enough to compress/save all the details.
The vidos of my K2 are recorded with a bitrate of max 12000 kbps, while the videos of a friend of mine are recorded at up to 24000 kbps (using a Sony ActionCam).

 

Sony ActionCam and the K2 are not comparable, The K2 has lens and DVR jointed by 3 meter video cable, which was limited to transfer high big rate video data.

 

For the screen shots you uploaded, the difference was cased by the slight sun/light direction and difference. the lens is not smart enough to adjust itself. in some section, it is clear enough, some section is not.

 

As mentioned, we can upgraded the video regulation to be 2K or 4K, but it is not able to transfer such data via video cable, and we are not able to get the reliable recording. We choice such design for hiding installation on motorcycle, we have to live with that.

Dec 30, 2018

Hi Rock,

 

thanks for your explanation. I got your point about the cable length, but I am curious now.

What kind of data do the cameras send to the DVR? Raw Data or MJPEG or something else?

I guess that the NT96663 within the DVR will do the final H.264 encoding.

 

Regards,

 

Frostie

Mar 6

I am not with you, Rock, that the compression artifacts in my videos are due to different sunlights. And that the cable length between the cameras and the DVR is the bottleneck, which would cause the artifacts.

 

The compression artifacts (as the name says) come from the H.264 encoding, which is done by the NT96663 within the DVR and not by the cameras. So the cable can´t be the bottleneck here. Maybe if we would talk about 2k or even 4k. But not at 1080p.

 

Given that, I first took a look at the technical specs of the NT96663. And that shows clearly, that the NT96663 can do a higher bitrate than what the K2 is using.

So I modified the V39 firmware and increased the default bitrate of 12kbps to (currently) 20kbps myself. And guess what happened? That compression artifacts are almost gone now, even when there are much details within the video (trees with branches, bushes, etc). Maybe I should raise the bitrate a little bit more to completely remove them. The drawback is, of course, that the size of the video files increased accordingly. 15 Minutes now takes 2,3GB instead of 1,4GB. But that is not important for me.

 

I also did a modification to solve my problem with the 720p resolution (https://www.innovv.com/forum/innovv-k2/resolution-always-revert-to-1080p)

simply by creating two firmware files with a fixed resolution of 1080p or 720p and a appropriate bitrate.

 

 

And the end, I was able to solve the problems myself. But it is disappointing that I had to, as there were not willingness from Innovv to solve them.

 

Regards,

 

Frostie

 

Mar 13

Hi Frostie,

 

Sorry for delayed reply as the forum fulfilled spamming messages.

 

It is amazing you edited the firmware yourself!!

 

We are very interested in your edition, do you mind send it for our testing? We'd like to see how it goes well.

 

Click below link you can upload the bin file.

https://www.dropbox.com/request/Ge24zlDutU0o8pShpR3U

 

I should say our engineers are not skilled as you are. I'd like to be honest.

 

 

 

 

Mar 13

would be interested in a higher bit rate as well if this can be done. I’ve noticed the video can get very grainy in some situations.

Mar 14

@Rock Liu

 

Just to avoid any misunderstandings. I am neither a developer nor an engineer. I am only an IT professional and stubborn in solving problems.

After I knew that the NT96663 could do higher bitrates than 12MBit (just read the technical specs) , I searched the Internet about information how to increase the bitrate. And as the Novatek chips are widely used in various dashcams, I was able to find plenty of information. All I had to do was to apply these information to the K2 firmware.

So the credits have to go to the people in the net, as they did the main work. I am only a beneficiary.

 

But I am curious why you are interested in the modified firmware. For Innovv, as the developer of the K2, is should be only a fingertip to increase the bitrate. Just change the value in the appropriate registers and compile the firmware.

Anyway...you will find the download link(s) below.

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Mar 15

@Frostie, Thank you for such input, we will do further testing and keep discussion.

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