Corrupt MP4 Files? Fix Them for Free with this Great Trick
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After recently playing around with a time-lapse app Droid Timelapse: Create Smooth Time-Lapse Videos With Your Android Phone Droid Timelapse: Create Smooth Time-Lapse Videos With Your Android Phone Read More on my Android device, I discovered that setting a long capture period resulted in a very large, corrupted file. Was it possible to repair it, and if so, how?

The Corrupted File

Sitting at 1.29 GB, the newly created file refused to play back in any of the apps on my phone. The first thing, then, was to quickly transfer it via USB to my PC The Fastest File Transfer Methods Between PCs and Mobile Devices The Fastest File Transfer Methods Between PCs and Mobile Devices PC-to-mobile files transfers are easy to do. This article covers five fast transfer methods between PCs and mobile devices. Read More . Once this was done, it was time to try the old fallback, VLC Player. This incredibly versatile app can play video files that are only partially downloaded, as well as all of the other amazing features it has 7 Top Secret Features of the Free VLC Media Player 7 Top Secret Features of the Free VLC Media Player VLC should be your media player of choice. The cross-platform tool has a bag full of secret features you can use right now. Read More , so it seemed a good bet.


Unfortunately, even the free and open source VLC Player was unable to show me what had been captured in the time-lapse video. I had to find another option.

Using a Video Repair App

Apps that fix dodgy videos are not in wide supply. They don’t come pre-installed on Windows or other operating systems, they’re (surprisingly) not included with video editing tools The Best Free Video Editors for Windows The Best Free Video Editors for Windows Everyone takes videos these days. Yet powerful free video editors remain rare. We present the absolute best free video editors available for Windows. Read More ; in short, they’re rare. As such, we tend to discard videos that don’t work.

In the case of my time-lapse project, this wasn’t a solution. I needed to see what had been captured, and so a video repair tool was really the only option. Eventually, I found a solution that might work – Video Repair from Grau GmbH. While a premium option is available, I first decided to try the corrupted file with the demo version. This has a cut-off point, which means that only the first 50% is repaired. Given the size of the file, however, this was worth the effort — after all, I didn’t want to pay for an app that would fail to repair the video.

Repairing the Video

With the app loaded up, I needed to have both the corrupted video and a similar file, recorded with the same camera and app (and of the same subject) as a reference, also saved to my computer. Once downloaded, Video Repair must be unzipped (natively, or with a tool like 7zip 7Zip: A Free Program to Unzip Uncommon Archive Formats 7Zip: A Free Program to Unzip Uncommon Archive Formats Read More ), rather than installed, and the unpackaged gs.exe file run to open the app.


After selecting the language, and taking note of the 50% limit which is clearly outlined, I browsed for my corrupted video file (MP4 and MOV files are compatible with this app) in the Choose movie… box, along with the reference file in Choose reference movie…. The movie is repaired by clicking Scan.

If successful, Video Repair will provide a list of fixes it employed to make the movie watchable. But if no list of fixes is provided, Video Repair cannot fix your video.

One Fixable Video, One Expensive App

Say, for example, that you have just one corrupt video you want to repair. Video Repair would be the sensible choice now you’ve been introduced, but there’s a problem. It’s expensive. To purchase the app would set you back €29 (around $33) and this only provides FIVE repair jobs. For an unlimited license, the price is €99 ($114). Now, if you find that you regularly have videos that turn out corrupt, this might be an option; however, finding the underlining causes of your corrupt clips might be a better strategy.

So, what do you do to repair the entire video? Well, you can pay the fee and buy the full version, or you can use some totally legal trickery to get the video restored in its entirety…

Double Up and Repair

As demonstrated by YouTube user R3DLIN3S, it’s possible to trick Video Repair into repairing the entire video. The idea is simple: we make a video file that is twice as long, and still convert just 50% of it. Because we doubled the video length, the file that is converted is our entire original file.

But how do we do this?


Begin by dropping the corrupt file into a new, dedicated folder (we called ours “Corrupt File”) and copy it so that you have two identical files — understand that this may take a while for larger files. Now, you should rename them; it’s best to give them sequential names, like VID1 and VID2.


Next, open the command prompt in the Corrupt File directory (hold SHIFT > right-click > Open command window here) and enter the following:

copy/b VID1.mp4+VID2.mp4

This takes a while, but will stitch the two files together into a single MP4, in place of the first file. So in effect, VID1.mp4 is now VID1.mp4 and VID2.mp4.


You can confirm this by checking the file size of VID1.mp4 — if it is now twice as long as it was previously, you’re ready to use the repair tool, as demonstrated above.

Buy it if You Like It!

Although we’ve demonstrated how to fix a one-off corrupt MP4 file, if you like the app and believe it will work for you in the future, then we would encourage you to spend money on Video Repair. But for a one-off fix, our legal cheat should do the trick.

So, a straightforward, quick and easy way to repair a corrupt or broken MP4 file. Does it work for you? Or do you have a better alternative? Tell us in the comments!

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  1. Damian PL
    September 18, 2018 at 6:53 pm

    Thank you for sharing this program! I've recovered my daughter's first steps, cause F@^#&N camera didn't save just that one video :D Cheers!

  2. Denis Vasquez
    June 22, 2018 at 7:28 pm

    1/2 of video is showing but with out sound.

  3. Leon_ID
    June 6, 2018 at 8:31 pm


  4. Leon_ID
    June 6, 2018 at 8:31 pm

    These tools are not free anymore. E.g. grauonline charges a fortune, and I wasn't satisfied with the result. Among similar tools, the only option I can think of is Restore.Media online service - worked like a charm for me. They have been free back in March, 2018 - maybe they charge something now

  5. chris
    January 2, 2018 at 9:36 pm

    Not working anymore in v3.1.0.1
    The tool knows it's two files and recovers half of it two times.

  6. Faith
    December 18, 2017 at 2:42 am

    Mine some clips running wont. Either uploaded place in one playing doesnt.

  7. RonaldDKTrump
    December 5, 2017 at 7:24 pm

    Why the output file only have 70 kb if my original corrupt file has around 900 mb??

  8. another way
    September 10, 2017 at 9:23 pm

    you could also try what I do sometimes:
    dump it into a few players first (I use GOM player)
    then try vlc player. A lot of the time this will work

  9. Praveen
    September 1, 2017 at 5:39 pm

    I tried this. But the app is creating two files, both of the same length, which are half the length of the original. I used version 3. Maybe the developers know the trick now, and the new version is still repairing 50% of the original. I cannot download the older version from anywhere. Please help.

  10. Praveen
    September 1, 2017 at 5:36 pm

    I tried this. But the app created two repaired files, both of same length, which are half the length of the original. I used version 3 . I think the new version knows the trick. I cannot download the older version from anywhere. Please help.

  11. Joe R
    July 19, 2017 at 11:41 pm

    Worked great. Well worth the about $35 US dollars. Pay people their fair wage. I had to turn on the option called NO ctts. Thank you to the software engineers who saved an important family video. Remember, read the help tips. The free demo mode worked great, and that allowed me to experiment with several options. My first demo try failed and then my second attempt with CTTS off worked great. Then once I knew it would work I made the purchase.

  12. JerryV
    July 3, 2017 at 10:48 am

    Thank you so much for this. I had a video file that had been corrupted on recording and thanks to you I was able to recover all the footage.

  13. Ganyman
    June 26, 2017 at 9:35 pm

    Perfect ! It works very well !

  14. Joyvel
    April 23, 2017 at 6:55 pm

    Thanks so much!!!

  15. Aaron
    January 24, 2017 at 5:16 am

    Doubles the file size of my mp4 but did not double the length, so it still only processed the first half of the file. :(

    • Dex
      April 15, 2017 at 6:36 pm

      I tested the trick several times and can confirm that by simply merging video files, the tool repairs 50% of the first video and 50% of the second video, even if they are one merged file.
      Then I removed the header of second video file before merging, using HxD binary editor. This is actually quite easy. Just start selecting bytes from beginning until you reach unrecognizable stuff (most likely video stream). My MP4 files had headers of about 450 bytes. You can recognize header by clearly visible words between lots of zeroes.
      I guess that this way the tool thinks that this is one big file.
      Removing the header of the second video file does not matter, because the second 50% is not recovered in demo mode, so the first 50% (first video file) is properly recovered.

  16. Audi
    January 15, 2017 at 7:56 pm

    Man .. This is just awesome :-* I love you :-)

  17. YouTube/JonnoPlaysCoC
    December 17, 2016 at 6:14 pm

    Thank you so much. This just saved me.

  18. Dalton
    December 13, 2016 at 2:42 am

    Haha.. if they didn't want you to come up with a way to trick it, they shouldn't have made the app so pricey. Great thinking and thanks!

  19. alan
    November 15, 2016 at 11:31 pm

    you da man! thanks for tutorial!

  20. Mitchell
    August 5, 2016 at 4:35 pm

    Worked for me! Thanks a bunch.

  21. Maximilian Kern
    August 2, 2016 at 8:05 pm

    Further Info: It indead doubles the file size but not video length

  22. Maximilian Kern
    August 2, 2016 at 8:04 pm

    The command copy/b file1+file2 seems not to double the length of the video as expected/explained. Atleast for corrupt videos ;(

  23. Venom
    June 15, 2016 at 5:36 pm

    Output video seems like slow motion

    • DonL
      August 9, 2017 at 7:58 pm

      Try change the frame rate