dashcam video - it is really mp4?

[Davidk]

This is a query for the format afacionadoes out there ..

I invested in a Navman dashcamera for the car - 1080p resolution etc. It's become the 'thing' to protect oneself in car crashes to be able to produce video of the event, esp to support an insurance claim. The video captured by it is supposedly a mp4 (thats the file extension), and the video on micro SD card inserts into VS and windows media player OK, but neither of them plays, or indicates it even has, an audio track despite the camera having a microphone. But the Navman app for it happily plays the video and an audio track too, whatever was said inside the car including the music from radio/cd player. So, clearly the recorded file has a recorded audio track that goes with the video.

So, what sort of mp4 video file would have an audio track that doesn't play in common players or editors?

[weaver]

There are many "dialects" in MP4, and it seems every manufacturer make his own private version. I also have to convert the recorded video from MP4 to "standard" MP4 before I can use it for video editing. Fortunately I found a program on my computer which can play the recorded video ( not the VS).
My camera ist not Navman, therefore I cannot tell you what procedure is the best. There are many video converters ( many of them online), you have to find the best one.

[Ken Berry]

David -- have you played it in VLC player? If so its Tools will give you codec info for both video and audio. If not, then MediaInfo or GSpot should help. Then we can start working out why you are not hearing anything in VS. And as Weaver has already suggested, using Handbrake or a similar converter might help.

[Davidk]

Hi Ken,
Thanks for that. Somehow I missed doing that originally, but have now done it. And VLC does play both video and sound; the device has pinhole mic, so the sound level is low, but you can hear it.
I also used a different method to get the properties of the clip; this time using windows, specifically explorer: rt click on file, properties, detail tab. There are other files recorded with the video clip - and they are not small, have no idea what they are/do tho.
First of all, here's the explorer properties screenshot, marked with the file being 'propertied' and those other NMEA files, one for each video clip.

and this one is VLC tools codec details. The model of the dashcam is in the bottom RH corner along with overprints of GPS coords, speed, date and time.

The thing that stood out in these 2 images was the frame rate: in the windows properties it's rounded down to 29, but the VLC data shows it as 29.97.

Seems odd that an mp4 file generated by a device sold in aussie (a PAL country, 25fps) would be using an NTSC frame rate, but apart from a standards issue maybe it doesn't matter?

Which leaves the question of why VS didn't think the clip had an audio track. So, to explore further I opened 2018, loaded the same file into the timeline, and selecting the clip chose the sound mixer function. This should have shown any audio track that is part of the clip as a wavy line within the clip box, even if the level was very low. And I got nix - nothing, so, another screenshot to show that, and I included the VS properties box in the image

The original question was about what sort of mp4 file wouldn't play an audio file. Revising that, why doesn't VS recognise or play the audio component of that clip?

[weaver]

Hi

The audio format may be the reason. It is a very simple audio ( sampling rate 32 kHz and with adoptive PCM), maybe VS cannot recognize this format (IMA WAV ADPCM 32 kHz). I could not find in VS specs this audio format, but maybe my documentations are out od date.
This is not a very common audio format, and many programs incl. Windows need a special codec. It will be probably easier to convert the stream into some common video and audio format.

[Ken Berry]

Did the dashcam come with any software?

[Davidk]

Hi Ken,
Not directly. The user guide did provide a link to obtain the navman viewer program, but it was actually to a mapping sub-site, and it took some poking around with google on the website to actually find the specific item for dashcam model miVue740. Once found (MiVue Manager v1.0.33.18.exe), download/install, 17mB. (Sidebar - it's a flashy website if you want to buy, but very lean to next-to-nothing re info on contacts or for any support like electronic copies of the user guide or reader software). And that was the program that initially told me there was an audio track in the clip, which led to my initial post here.

Seems really odd that a reputed brand like navman would use formats for such an item that are not 'industry standard'. If the clips ever need to be used seriously - eg, the local police now regularly call for dashcam footage in crime incidents - a standard format able to be read by everyone would seem to be essential.

[Ken Berry]

David -- I just did a quick Google search using "IMA WAV ADPCM" as the search target, and found out this format has been around for quite some time. One post from 2006 implied it was a good deal older. And one from 2013 was complaining about the format in a dashcam! Sound familiar.

However, there appear to be converters for it. One is at https://www.erightsoft.com/audio-converter.html though I cannot of course offer any guarantees, never having used it. Another post there hinted that Audacity may even be able to handle it...

[weaver]

Some manufacturers always prefer some exotic formats, just to be different from the main stream....

[Ken Berry]

This one's main attraction seems to be a high compression factor, making for a much smaller file than other formats. And Microsoft apparently tweaked it into a slightly different format of its own, different from the one we are discussing here.

[RobertOZ]

I have a VicoVation VICO-TF2+ full 1080P HD Dashcam, which has served me well since 2012 and in that time have never had an issue with editing in any version of VS, audio has always been fine

[Davidk]

As to that converter link - lots of good stuff there, but getting a download to try it out proved to be impracticable - links etc that seem to do that just led to more read and poke etc etc. I gave up eventually.
Re audacity, I had doubts as to whether an audio editor would open a video clip, but I tried opening a dashcam clip in audacity to verify that implied claim. And no, audacity won't open it. I got an error message as follows:

[Ken Berry]

I wouldn't have tried opening the whole clip (including video) in Audacity. I would have tried hiving off the audio part -- even if it shows as empty in VS -- and trying that in Audacity.

Sorry about the converter... Have you tried putting the whole clip through something like Handbrake?

[Davidk]

yep, was doing that as you responded.
I intended to change the audio to mp3, and whilst I as checking the settings for the output, noticed that the video was set for peak frame rate, which implied some variability and given VS known issues with variable frame rate, changed the spec for the output to fixed frame rate. then re-coded it. Was a bit surprised that for a 3 minute video the re-coding took over double that time.

And inserting the result into VS2018 gave this, one problem solved and another lurking . . .

The problem solved - re-coding the audio to mp3 now allows VS to recognise it and give an audio spec in the properties tab.
The problems lurking - (edited update)
1) I snapshot this image with the sound mixer on, and expected it to show the audio waveform in the clip box. And altho the properties say there is a recognisable audio content there, the sound mixer apparently can't load it - that loading waveform message in the clip box stayed there for a minute or so before I snapshot the screen.
2) volume. playing the clip as imported, volume is Ok. Changing the volume by the attribute tab, to either 200 or 500 - and a clip plays (as a clip or as a project) like there is no sound at all.

[Ken Berry]

Can you try it in X10, or another brand's editor if you have one?