Overlay Video Synchronization with BT1 OBDII & XGPS150

[cwatson]

Evening,

I have been working to get a good A/V & DAQ setup for my upcoming track weekend. I was pleased to find that V17 supported my external microphone (Olympus ME52) and am able to get a good, clear recording with the mic in the trunk. Now that the sound is clear, it has become evident there is a large delay between the video/sound and the accelerometer/gps/obdii reader.

I have uploaded two videos: one with the only the GPS attached and the other with both GPS and the BT1 OBDII adapter attached. I disabled wifi in case that might have some effect.

XGPS150 ONLY: http://youtu.be/f2LFxZWwpY8
XGPS150 & GOPOINT BT1: http://youtu.be/ltBpZ4x-zwo

I recorded two videos earlier today (too large to upload) with the XGPS150 & BT1 combo. One video was off by ~1-2s and the data lagged the video in the other by ~3-5s. This was with an identical setup. No background apps are running on the Ipod.

I fiddled with the "Overlay Synchronization" in expert settings. Setting it to 0.0, 3.0, and -2.0 seconds all resulted in an indeterminate amount of lag. I also tried setting the GPS, OBDII, and accelerometer delay to 0.0s. The alternate settings all seemed to make it worse.

I think I am misunderstanding the direction of the synchronization times. If the video is leading the data, what is the correct direction to make adjustments?

All advice is welcome.

Thanks,

Chris

[Harry]

Hi,

Please note only the Overlay Synchronization has an effect after you have recorded. All other delays are applied during recording, which means changing them has no effect on existing recordings.

Delays are defined as the gap between the time of the real event and the time the result is received by LapTimer. This is the reason all delays are positive.

In case video is ahead of recording, either the Overlay Synchronization (which is actually the Video sensor delay) is too big, or the sensor delay is too small.

In case you run out of delay range (i.e. need to reduce a delay below 0), increase all other delays to achieve the same effect.

I doubt any delay is wrong by 2 or 3 seconds, in case like this it might be best to start with the default values.

On the audio topic: are external audio and video in sync? Just curios as I have no experience with this. Furthermore, have you used any adapter for the named mic or is it connected with stock plugs? Still looking for a good testing device here...

Hope that helps.

Harry

[cwatson]

Harry,

Thanks for the prompt reply.

Regarding the a/v setup:
I am using an Olympus ME-52 microphone with a TRRS splitter cable. The microphone is designed for voice recording and is very sensitive. I seem to have found a good compromise of engine/tire/brake/wind noise by locating the microphone in the trunk. It was very important to 'float' the microphone. The microphone body cannot be touching any surfaces. Be careful of running the radio as the microphone picks up interior sounds quite well. Similarly crisp sound can be had by recording in the center console or a rear cubby/cup holder. The A/V is synchronized. You can tell in the above-linked videos during the shift where you can see the car pitch. I have also tapped the microphone in view of the camera to verify the synchronization.

Olympus ME-52 Microphone:
http://www.amazon.com/Olympus-ME-52W-No ... B000MYPPPE
TRRS Splitter Cable:
http://www.amazon.com/StarTech-com-MUYH ... B004SP0WAQ

A stereo extension cable is used between the microphone and TRRS splitter cable with no ill effects.

I also tried using a powered lavalier microphone from radio shack but no audio was recorded through the Camera or HLT:
http://www.radioshack.com/product/index ... Id=2102927#

I am going to do some more runs during lunch in attempt to diagnose the synchronization issue. I wonder if it could have something to do with the fact I am recording without crossing a trigger?

Thanks,

Chris

[Harry]

Thanks, will check that audio configuration.
There should not be a difference from triggered timing to manual timing for synchronization.

- Harry

[Harry]

Thanks again, this configuration definitively works fine.

- Harry

[nismo09]

Harry,

Thanks for the prompt reply.

Regarding the a/v setup:
I am using an Olympus ME-52 microphone with a TRRS splitter cable. The microphone is designed for voice recording and is very sensitive. I seem to have found a good compromise of engine/tire/brake/wind noise by locating the microphone in the trunk. It was very important to 'float' the microphone. The microphone body cannot be touching any surfaces. Be careful of running the radio as the microphone picks up interior sounds quite well. Similarly crisp sound can be had by recording in the center console or a rear cubby/cup holder. The A/V is synchronized. You can tell in the above-linked videos during the shift where you can see the car pitch. I have also tapped the microphone in view of the camera to verify the synchronization.

Olympus ME-52 Microphone:
http://www.amazon.com/Olympus-ME-52W-No ... B000MYPPPE
TRRS Splitter Cable:
http://www.amazon.com/StarTech-com-MUYH ... B004SP0WAQ

A stereo extension cable is used between the microphone and TRRS splitter cable with no ill effects.

I also tried using a powered lavalier microphone from radio shack but no audio was recorded through the Camera or HLT:
http://www.radioshack.com/product/index ... Id=2102927#

I am going to do some more runs during lunch in attempt to diagnose the synchronization issue. I wonder if it could have something to do with the fact I am recording without crossing a trigger?

Thanks,

Chris

Chris - what type of stereo extension cable are you using? I bought a ATR-3350 Lavalier microphone because it has the long cable but alas it does not work as you found out. I do have the StarTech splitter.

Bump