I know almost nothing about video editing/encoding, other than that there are many ways of encoding video/sound and wrapping it all up into an avi or whatever.

So I've taken some videos in mp4 format on my phone, which play fine on my phone but when I uploaded them to Facebook, the sound was out of sync. I copied the mp4s to my PC and ran them with Quicktime (ugh...) and they played out of sync too.

Fine, something funky must be going on with the encoder I thought, so I loaded it into Avidemux 2.6 (tried Virtualdub but it crashed when I tried to play it), changed the audio encoder, saved it as an avi and - hooray! The avis play fine on the computer. I reuploaded them to Facebook and oops - the sound's out of sync on the Facebook version.


Can anyone help? I'm guessing Facebook are pulling it apart at their end and re-encoding it, but is there anything I can do at my end to stop this happening?

I have no idea what the originals used, but the encoders on the version that plays fine on my PC (but not on Facebook) use 'MPeg4 AVC (x264)' for the video and MP3(lame) for the audio. I have no idea what those things are but they seemed to work after a bit of trial and error.

Does your phone produce an interlaced or progressive scan file?

https://www.youtube.com/watch?v=LV8UDBsf45Q <-To tell the difference.

If you have a choice, try using progressive scan on your phone. Resolution options should be 1080p/i 720p/i etc (choose p for progressive scan).

Not a clue. It's a Samsung Galaxy S2.

It's charging at the moment and won't let me use the camera so I'll see if there's any options in a bit.

Quote from Crashgate3 :

It's charging at the moment and won't let me use the camera so I'll see if there's any options in a bit.

That seems really broken. That you can't use the camera while its charging.

It's just if the battery is below about 2%. Once it gets a bit of juice it works.

I checked the options but it doesn't mention whether it's interlaced, just gives a list of resolutions.

Then try to upload at 1280x720, not at 1920x1080. See if that makes any difference.

dont think its a problem with the resolution...i always record at 1920x1080 (also SGS 2) and it works just fine.

Along the same lines; does anyone know why that some MKV files get progressively more and more out of sync while watching them? This doesn't affect all MKVs, just some of them, but it happens on both my TV (which plays files from USB), PS3 and my PC with some files. As they play, they get more and more out of sync. I have to fast-forward a little bit to re-sync the sound, but it goes off again as it plays after that too.

bad rip id say...if it happens on different platforms it isnt a software fault.