Mystery: 3GB mp4 file, says it is 0 length, can it be fixed?

[Tazling]

I got a vid from someone who recorded a tv show for me.

It's an mp4 and it's over 3GB in size, but when I load it into VLC it says the length is 00:00. And it won't play.

Is there any way to make VLC (or some other app?) re-evaluate the video and recalculate the runtime? I've used Handbrake and VLC to convert and rip videos (converting my bulky DVD collection slowly to a NAS drive, takes forever). But I've never had one that reports itself 0 length before. I do have the "ff" suite of tools but am not expert in their use. Just a dumb video collector / curator not a dedicated video hacker.

So is there any hope of rescuing this TV show? I don't expect it will ever be rebroadcast. So if the only extant copy is corrupt, argh.

[davexnet]

You can open the video in Mediainfo and see what it says about the video and audio streams.

You can also try a lossless conversion to MKV by using mkvtoolnix-gui

[Tazling]

Thanks for the hints. I will have a look at those tools...

[some minutes pass: update]

Got MediaInfo. What a strange UI. Anyway, the popup subwindows inform me of various things: the length should be 1 hr 26 minutes, for one.

But a flag called IsTruncated is set to Yes. That seems like a smoking gun right there. Off to research IsTruncated. [google google] well it just seems to mean that the file is corrupt in some way.

I guess I will try one of the many "video repair tools" out there with a free trial, just to see if it makes any progress... meanwhile DL'ing mkvtoolnix per your suggestion. [... more minutes...] results so far: mkvtoolnix rejects the mp4 file as "unknown format" but "Stellar Repair" accepts it and is chugging away. I may have to pay some bucks for Stellar to do a real conversion (more than just a teaser) but that could be worth it, this is a rare TV show.

I just hope Stellar Repair isn't some kind of trojan horse.