Fixing corrupted mp4 files

 I went to grab some files from my Rexing dashcam, but they wouldn't play. It seems there's an issue when the dashcam powers off with the engine. So I went down the rabbit hole to see if I could recover them. Of course, most options didn't work, and some seem to be scams.

These are the files I'm working with

MediaInfo details

454295552B S2026_0817_153842_007.MP4 - simple repair

319029248B S2026_0817_165138_001.MP4 - hard repair

565644598B S2026_0817_174309_001.MP4 - reference file

Kind of worked

Clever Online Video Repair recovered the more difficult S2026_0817_165138_001.MP4 file. It recovered 314244981 bytes for $6.72, including tax. On S2026_0817_153842_007.MP4, it recovered 448,217,987 bytes for $7.35, including tax. You should be able to sign up for better pricing, but it requires sending you emails, which it seems unable to do. The video looks good, and they appear to be full-length, but the audio was not good at all. Fortunately, I did not want the audio anyway. The previews looked good, but I waited to look at the others before paying for the repaired files since I really wanted an app.

Repaired S2026_0817_153842_007.MP4

Repaired S2026_0817_165138_001.MP4

EaseUS Fixo Video Repair app appears to work from the previews, but you need to sign up for $49.95/year to get the actual files. But if you go through the app, the price is higher; then it offers 40% off if you decline the first offer. That felt scammy to me, so I didn't pay them. The interface looks more polished than Stellar's, at least.

Did not work at all

Paid

Stellar Repair for Video online chugs for a while and shows you a thumbnail that looks like it works, but then wants you to sign up for a $9.99/month subscription to get the video, or optionally buy and download the software for $ 49.99. Since it was the top-rated option I found, I bought the app that claims to fix photos as well for $59,99. It did not work on either file. A total waste of money, and buying the software doesn't get you off the "free" level online. The refund request link says it sends a code, but it didn't work for me. The interface is pretty sad too. You can't even resize the window. I'll be watching PayPal for any more charges.

Free

Untrunc free app. Did not work for either file. Its GUI is about as primitive as Stellar's. It is resizable but closes as soon as it is done so you can not see the output. 

The end of the output from the command line is:

Info: Found 7980 packets ( mp4a: 4509 avc1: 3471 avc1-keyframes: 289 )

Info: Duration of mp4a: 2min 24s 288ms  (144288 ms)

Info: Duration of avc1: 2min 24s 625ms  (144625 ms)

Warning: Unknown sequences: 11

Warning: Bytes NOT matched: 3.26MiB (0.7517%)

Warning: Skipped atoms in mdat: 290 -> 5.66MiB total

Info: saving F:\CARDV\Movie\S2026_0817_153842_007.MP4_fixed-s1-k.MP4

src/atom.cpp:479: void BufferedAtom::write(FileWrite&, bool): Assertion `end - start == new_length' failed.

VLC Media Player: Rename mp4 to avi. Open VLC Media Player, go to Tools > Preferences > Input/Codecs, set "Damaged or incomplete AVI file" to Always fix, then try playing your MP4 (or rename it to .avi). You can also use VLC’s Convert / Save tool to re-mux the file. Neither way worked.

FFmpeg: Run the command ffmpeg -i corrupted.mp4 -c copy repaired.mp4 in your terminal or command prompt to quickly re-wrap broken headers without re-encoding. Choked when opening the files. Output:

[mov,mp4,m4a,3gp,3g2,mj2 @ 000001b2ed85adc0] moov atom not found

[in#0 @ 000001b2ed876c40] Error opening input: Invalid data found when processing input

Error opening input file S2026_0817_153842_007.MP4.

Error opening input files: Invalid data found when processing input

What system should I get bullet points

Not sure why people do not search the group before posting questions like this. You mainly get loads of people trying to sell you their stuff and others suggesting junk. You can hire someone to set it all up, but odds are good you will end up with their standard setup, not something tuned to your needs. What you need to know:

Avoid WiFi. When you are trying to ID or detect with AI, you want every frame. You will not even notice most frame drops until you are trying to get the one you need that is not there.

Cloud is for backups only. Record to an NVR, and it does not hurt to record to an SD card in the camera as well. My personal favorite is a PC running Blue Iris, since it is dead simple to learn, talks to about everything, and costs only $100. If you are tech-savvy, there is Frigate, which has similar features and is free but has a lot more of a learning curve to set up

Record 24/7. Anything less will miss something.

Filter with AI. You want AI to do the work of looking at all the motion triggering your cams, or you will come to ignore them. Note there will always be a trade-off between always notifying you, even when it is nothing, and missing something significant. You will need to tune this over time. Another reason to do it yourself.

Each camera needs to match its target. Look at where you want to monitor, then where you can put a camera. From there, you have distance and view angle. A site like https://www.jvsg.com/calculators/cctv-lens-calculator/ will help sort the specs you need to get the detail you are looking for. Prefer cameras that support ONVIF but require at least RSTP support.

Lighting: lots of models claim color night vision these days, but get there by slowing the frame rate down to a point where moving objects are blurred or even ghosted. Or they get there with white lights in the camera. Look for videos with moving things in them. Stills are useless. That said, the best are ColorVus, which will give you cloudy-day-looking video for a target area where you can make out your hand in front of your face. In darker areas, you will want to go with IR for night vision. It is much better to use external lighting to get the level you need, since lights attract bugs. Cameras that turn on white lights when motion is detected are a plus.

Networking: As with any IoT, you should isolate them from your main network and the internet. Either have 2 Ethernet cards in the PC, one for the camera network and one for your main network, or look up VLANs. Do not get distracted by NDAA-compliant claims. No camera should be exposed to the internet.