Can't open mp4's in Sony Vegas

[ClownInBrown]

Hey there!

I've two mp4 files.

a) is 1.27 GB big
b) is 4.29 GB big

According to GSpot, both use the same codec. H.264/MPEG-4 AVC
And I can playback both of them in MPC.

The problem is, I can't open b) while a) works without a problem. The following message pops up when I try to open b)
"The file is most likely corrupted or of an unknown format"
So, I assume this is due to the file size and I wonder if there's any fix for that?

[Baldrick]

You can try remux it to a new mp4 using mp4muxer or YAMB and see if it works better.

Or convert it to an avi using mp4cam2avi.

No reconversion of the video.

[ClownInBrown]

Or convert it to an avi using mp4cam2avi.

Tried that and it gave me this error: "Thread error: Invalid floating point operation"

About the mp4 to mp4, I'm rather sceptical that the new mp4 will work in Vegas. Also, I guess it will take ages to encode.
But if there's no other solution, I'll give it a shot!

Thanks so far!

[Baldrick]

No, remuxing a mp4 will just take some minutes as it's no encoding. And you can also try cut it while you are remuxing.

[ClownInBrown]

Oh okey, will do it then!

[ClownInBrown]

So, I've been playing around with it and have got a question or two.
How do I actually save the file as a new mp4, is that even possible?
Or isn't it needed because with the 'demultiplex' option you can basically 'restore' your old mp4?

[Baldrick]

YAmb or mp4muxer??

[ClownInBrown]

My bad.
mp4muxer that is.