(I'm not sure if this is the right forum section for my post, but here goes...)
I have a problem with a .mp4 file, the sound plays at a normal rate, but the video is extremely slow: for about 50min. of sound, there is 3h10min. of video
The file was created on a Windows phone, Lumia 620 to be specific, and it was corrupted when I copied it from the device. I managed to open it with GS video repair, but now I have a file with a huge video delay... Also, I managed to extract the sound, I had no trouble there.
Any ideas on how to fix this?
It does help if you read the sticky at the top of this forum. Without complete details we all end up taking a lot of time with blind back and forth guesses.
If you're playing the file, there must be a Player and a Version Number for that Player. You should include that information. Of course the OS would help too. We can't assume that from anything you've posted. Certainly files from Windows phones can play on Macs.
First, I'd suggest testing playback in the free VLC media player.
Second I'd suggest opening the file in the free MediaInfo and looking at the complete specs for video and audio and posting that here.
Both utilities are cross platform.
Some players have problems with variable frame rates or the frame rate flags (or lack of).
It's possible that your repair impacted the frame rate flag (if there was one).
It's also not clear how you determined the file was corrupted to begin with so you should explain.
Thank you for your guidance on the matter.
Anyway, I got help on another forum, so I'll share the solution, if anyone else runs into the same problem.
First of all, the file was unplayable in different players, this is how I determined the video was corrupted.
I compared the framerate with a working clip from the same device with MediaInfo, it was too low, so I used MkvMerge to change the fps (load the source, highlight the video stream and set the FPS to the desired value in 'format specific options' tab).