How come videos work fine with any dot ending?

[johnharlin]

I used virtual dub to trim a mp4 dx50 video. The only option to save was in .avi. However, in order to make the videos uniform with other parts of the video I already edited in avidemux and saved as .mp4, I change the virtualdub .mp4 videos that were saved in .avi back to .mp4 just by retyping the ending and it worked fine. That is, when I used vlc player to open the the typed in .mp4 videos they opened fine and played fine. So then I retyped the ending to .mp2 and it played fine as well. So now I am somewhat confused about the purpose of the dot endings. What is the point of the different endings if they all seem to play fine with any ending you type in.

[jagabo]

Media players usually look at the contents of the file to determine the container, not just the extension. Windows Explorer uses the extension to determine what the file type is (and hence, what program to use to open it). So if you change .AVI to .XYZ and double click on the file Windows won't know what to do with the file. But if you open the file with a media player it will see the AVI data structures in the file and play it.

[Cornucopia]

Media players usually look at the contents of the file to determine the container, not just the extension. Windows Explorer uses the extension to determine what the file type is (and hence, what program to use to open it). So if you change .AVI to .XYZ and double click on the file Windows won't know what to do with the file. But if you open the file with a media player it will see the AVI data structures in the file and play it.

Some do, some don't.

Note that the common factor in the OP's scenario is h264 video codec. With most all current media players, h264 support is ubiquitous, regardless of the container.

Scott

[lordsmurf]

h264 support is ubiquitous, regardless of the container.

Most people forget (or don't know) that H.264 doesn't even require a container. That usually blows their mind until you ask them this simple question: "HDTV is H.264 right? (Rhetorical.) So what container file do broadcasters use?" ... followed by drooling, "uhhh", and similar responses.

Same for CD audio.
DV video.
etc.

Completely oblivious.

[jagabo]

So what container file do broadcasters use?"

MPEG transport streams.