Harry's GPS Suite Forum

I tried out for the first time today recording a video and then overlaying the driving data onto it. I watched the raw video then the overlayed video and I was surprised by the amount of artifacts compared to the raw video. Are my expectations set too high or is this not normal?
This video was done on a Nexus 5 with Petrolhead v18.0.16

Raw: http://youtu.be/PMEQEFELg1c

Overlayed: http://youtu.be/OYjfD_5Jy-Q

Every decoding / encoding cycle adds additional artifacts. Video compression algorithms used for consumer level devices typically do not use lossless encoders, which means every run will loss a bit quality. In case you want to trade some space against quality, you can select the highest video quality level in LapTimer Settings (Overlay Quality). This will increase file size by roughly 30% compared to "Normal Quality".

Btw. you need a better mount. In terms of quality, this will add a lot more compared to quality settings. Recommendations are included here: http://www.gps-laptimer.de/Compatibility_Android.html Furthermore, please turn off the video stabilizer. It seems to not do a good job for the Nexus 5. Not all devices allow a manual on/off here, try the settings button from the Video View.

- Harry

Ok I'll try changing the quality.

Yes watching the video I realized that I need to figure out a way to dampen the vibrations and or find a different mounting location.

I think the video stabilizer is already turned off.

I checked the specs and see the N5 has an optical stabilizer. The odd thing about this stabilizer is it cannot be turned off (matches the snapshot above). This link discusses the differences between the N4 and the N5. While the N4 has a software stabilizer that can be turned off, the N5 can't be turned off. Stabilizers are made to stabilize videos recorded by a human with the device in its hands. In general, these stabilizers run into big issues when used in cars with higher frequency movements. The effects can be seen on your raw video link above...

Please check the mount linked and recommended on the Compatibility page. I tested numerous mounts and most are not good enough for in car recordings. The RAM mount linked generates very good recordings when attached to the windscreen.

- Harry

Saw the overlay artifact issue on my recordings from yesterday. I was also using a different RAM mount, to keep the mount itself out of the video, but the additional axis passed much more vibration through to the phone.

I will try the largest overlay size now.

Question: Does video synchronization value (0 - 3s range, currently using 1.0) have any relation to overlay artifacts?

No, the overlay artifacts are usually due to compression. Normal compression shows some artefacts, while High should show nearly none.

- Harry

I processed this version using the least compression, but still has artifacts. I'll go back to the prior RAM mount next time, does the vibration make the artifacts worse? This file is 2 minutes 46 seconds @ 107k.

https://drive.google.com/file/d/0Bxw95o ... sp=sharing

The overlay I created during the beta, that also had OBD content, is 3 minutes 14 seconds @ 641k. Was that version uncompressed? Any possibility to have an option with no compression?

https://drive.google.com/file/d/0Bxw95o ... sp=sharing

Select 720p as a resolution, it isn't the default.

The beta used H.264 encoding - which is not available in the production version due to license topics. Furthermore the beta had a ridiculous setting for compression and generated far too big files. The current "High" quality is approximately double the size of the raw video (which is encoded in H.264 too) - to compensate the weaker compression capabilities of MPEG4SP2 currently used.

Btw. you have used "High" quality, not "High" compression - right?

I believe vibration (not compensated by a stabilizer) increases artifacts as it cannot be compressed as well as two consecutive video frames being practically the same. But I'm not deep enough in this topic to be sure...

- Harry

Confirmed. Overlay Quality is set to "Huge Size, Highest Quality"

What's your wording proposal for an even higher quality / bigger size? "Unbelievable Size, Higher than Highest Quality"?

- Harry