ARECORD B40D not recording under acceleration?

[wkearney99]

I've got a B40D on the windshield and rear window of my Porsche Cayenne GTS. It works pretty reliably. It's nothing special but OK for my interests most of the time.

This past Saturday I had it in the car when running an autocross. Most of the time it worked as expected. When driving up to the start and around the lot it worked fine. During the first run it also worked fine. But during subsequent runs the .MOV file it recorded won't play. Videos before and after it are fine. Just ones right from the start are 'defective'.

I tried playing from both files copied to a local hard drive and from the card directly (via a USB3 reader).

Anyone else seen this kind of problem? Like I wrote, it records just fine during the drives around the lot and up to the start. But the runs where I nailed it off the starting line won't play.

The card used for the recording is a Samsung 64GB Evo (orange label). It was full when I pulled it out of the dashcam. It lives in the car all the time, and has been reliably recycling old files when it runs out of space.

I wouldn't normally expect to use this for autocross. But the 3M picture hanging strip held it onto the glass just fine, that and I'd forgotten it was in there. (You normally remove EVERYTHING from the interior). That and I hadn't brought along my GoPro 4 or any of it's mounts.

Any tools out there I should try to use for fixing them or extracting at least part of the videos?

 

[jokiin]

try turning G-Sensor off if it's on and see if you still get problems, doesn't help you with the broken file but may prevent it happening in future

 

[wkearney99]

I just ran one of the clips through recover_mp4 (from: https://www.videohelp.com/software/recover-mp4-to-h264) and managed to extract some video. So, yay!

I have the dashcam set to not record audio.

The log during the run reported:

recover_mp4 v1.88 (C) 2011-2017 Dmitry Vasilyev <slydiman@mail.ru>
http://slydiman.me

Writing H264 video file '2017_0520_095852_080A.h264'...
Video format: AVC video 1920x1080, High Profile, Level 4.1
Assuming max AVC/HEVC NAL unit size (IDR) 0xEA3800, (non IDR) 0xFFFFF
Used AVC templates: QuickTime MOV
WARNING: Cannot find 'esds' atom inside audio header 'audio.hdr'.
Ignoring audio
Audio format: Assuming audio stream is PCM, 32000Hz 1ch 16bit
Searching 'mdat' atom in '2017_0520_095852_080A.mov'...
mdat (32-bit) payload from 0x70F0 to end of file (invalid end of mdat 0xB03DEA02)
 PCM: 0x000070F0 [0x   38F10]
H264: 0x00040000 [0x   1E48C] -> 0x      19 {65 88 80 00} IDR frame
H264: 0x0005E48C [0x    C524] -> 0x   1E4A5 {41 9A 00 02} P frame
H264: 0x0006A9B0 [0x   223D8] -> 0x   2A9C9 {41 9A 00 04} P frame

...(a whole bunch more lines like these, but no other errors)...

 PCM: 0x06350000 [0x    FA00]
free: 0x0635FA00 [0x     600]
 PCM: 0x06360000 [0x   100AE]
H264: 0x063700AE [0x    9843] -> 0x 5499EC2 {01 00 00 00} P frame
 PCM: 0x063798F1 [0x    670E]
skip: 0x0637FFFF [0x       1]
Complete!
H264 IDR NAL unit size: Min 0x9C4C, Avg 0x2345C, Max 0x3BE48
H264 non-IDR NAL unit size: Min 0x1128, Avg 0x8DB4, Max 0x4BD20
Audio frame size: Min 0xE12, Avg 0xFA00, Max 0x38F10
Skipped 9 blocks: Min 0x1, Avg 0x1, Max 0x1
WARNING: The current max AVC NAL unit (IDR) size 0xEA3800.
WARNING: The current max AVC NAL unit (non IDR) size 0xFFFFF.
Try to change it adding parameter --avcidrmax 35E74 and/or --avcxmax 443D0
'2017_0520_095852_080A.h264' created, size 88749829 (85.064%)

 

[wkearney99]

try turning G-Sensor off if it's on and see if you still get problems, doesn't help you with the broken file but may prevent it happening in future

Ugh, I hate trying to use the UI on this thing to adjust anything. It's just... bad.

I do like having the G-sensor for regular driving. Mainly in the event of an accident. I've had it already record some files to the RO folder after sudden braking maneuvers. Thankfully the beastly brakes in this thing saved the day.

Hmmm, that could have possibly been the problem though. There was no RO folder on this card, as I've seen on another that had braking-triggered recordings. I swap cards periodically, if just to make sure the cards are still working and videos are being recorded. I keep at least one spare card in the car to be able to do quick swaps in the event of a real incident. No need, thus far, but better to be prepared.

I'm thinking maybe the hard acceleration and braking during the maneuvers might have triggered the G-Sensor and since the card was full it's firmware wasn't prepared to suddenly create the RO folder and put the file in there. Is that likely?

Since I did manage to use a repair tool to extract the video, it's clear the dashcam stayed working and recording the whole time. Perhaps you're right and firmware was unable to deal with saving it properly.

 

[wkearney99]

What I'd love to find is a dashcam that I could control from an app on the same wifi network and use that to transfer clips automagically.

The car has it's own WiFi network and internet uplink. That and the house's WiFi network reaches to it's parking spot.

It's not a terrible chore to swap microSD cards but being totally hands-off with it would be fantastic.

 

[jokiin]

since the card was full it's firmware wasn't prepared to suddenly create the RO folder and put the file in there. Is that likely?

not really but the cheap public solution they use for these has a poor reputation when it comes to the G-Sensor and the cameras are generally far more stable when it is turned off

What I'd love to find is a dashcam that I could control from an app on the same wifi network and use that to transfer clips automagically.

The car has it's own WiFi network and internet uplink. That and the house's WiFi network reaches to it's parking spot.

It's not a terrible chore to swap microSD cards but being totally hands-off with it would be fantastic.

a lot of people ask for this, the size and quantity of files to be transferred don't make for a practical solution though, not with currently available tech at least

 

[wkearney99]

Oh, I don't know about 'currently available tech'. Stuff like Eye-Fi was doing WiFi sync with their SD cards a decade ago. The trick there was the card was 'passive' inside the camera and you had to leave the camera on for the CPU on the card to do the sync. Some cameras were more troublesome with this than others, but it generally worked.

Me, I'd rather have something that ran from the home network side of things. A program, or scripts that ran from a computer in the house, upon detecting the dashcam was nearby. As in, the dashcam m-DNS name has just appeared in the local network, so start pulling data from it. Sure, the car would have to remain 'on' or the dashcam's 'parking mode' would have to stay alive. But it would be pretty trivial for the computer side of things to deal with keeping tabs on download completions.

With the storage abilities of most current phones or tablets, especially when using things like microSD OTG dongles (like this one). I use that one now to pull video off the microSD card. It can just as easily be used as removable storage on the phone itself were it pulling data from the dashcam wirelessly.

Anyway, it's well within the realm of technologically possible. Trouble is the vendors don't really seem to have the insight as to make the pieces work together that way.

 

[Gibson99]

A lot of it is lack of demand and amount of r&d it would take to make it work right.

Sounds like you and I could get along just fine (geeks who like to race). I agree those would be great features but like jokiin says, the g-sensor used in the b40 and a118 (not exactly the same device) is not reliable. I leave it turned off in mine.

Meanwhile, my a118 worked great for recording an autocross:

And then 3 days later, this happened.

 

[jokiin]

Anyway, it's well within the realm of technologically possible. Trouble is the vendors don't really seem to have the insight as to make the pieces work together that way.

it's not as straightforward as it may seem, nothing to do with insight, want or desire, it would obviously be an attractive feature

 

[wkearney99]

As a developer and IT consultant for over 30 years, I've got a pretty good grasp of what's technically possible. And embedded gizmos are notorious for being "almost there", import ones even more so. That and lots of programmers for these things don't live similarly to the customers buying the stuff. You end up with decisions being made, for no good reasons, that arbitrarily cripple potentially interesting uses. That and making mass-market solutions that might require cross-platform, multi-lingual support are even more difficult for management and the developers to effectively implement. But it sure isn't the technology acting as the impediment.

 

[wkearney99]

Sounds like you and I could get along just fine (geeks who like to race). I agree those would be great features but like jokiin says, the g-sensor used in the b40 and a118 (not exactly the same device) is not reliable. I leave it turned off in mine.

Ugh, sorry to hear about the accident. That was a nice big autocross map. Fun!

I did manage to salvage the h.264 stream from some of the videos. I just have to bone up on my ffmpeg skills to get it back into a proper container. I operate the camera with no audio, as to avoid any unwanted recording from inside the cabin.

Good advice regarding the sensor, I'll have to revisit how it's configured and see about disabling it. The UI on it is to wretchedly annoying that I hate bothering. But it was cheap and fits in a relatively anonymous kind of way in the both windshield and back hatch of my Porsche. I'd hoped the screen would allow for at least some in-vehicle control but the menu control and the buttons make it pretty annoying.

Do any dashcams support a separate external mic?

 

[Gibson99]

Only one I can think of isn't specifically a dashcam. It's an action cam that can do dashcam stuff. It's the GitUp git1. It's nowhere as discrete as the a118 plus it has a lipo battery so it's not good to leave in the car all the time, but it's a very good camera both day and night, and supports external mics via its USB port.

 

[wkearney99]

It's the GitUp git1. It's nowhere as discrete as the a118 plus it has a lipo battery so it's not good to leave in the car all the time, but it's a very good camera both day and night, and supports external mics via its USB port.

I did some searching here last night and also came across the Git1 and Git2 cameras. I also prefer the more discrete look of the B40D (or others in the series).

I'd be willing to go the route of a DVR-with-separate-cameras route if that had other options. But I didn't run across any with the separate mic feature.

Which seems like most aren't geared toward external mics, rather 'better ones' for the interior?

I'd be willing to set aside the external mic feature for something with a simpler way to toggle the mic. The B40D is tedious to try and do this, and lacks a clear indication of the state.

I may have to punt and jump to a Blackvue to get a better regular use experience.