Codec/File extension question

[chibunda]

Originally Posted by Pad

I recently downloaded a number of .avi files. When I right clicked their properties in Windows explorer and looked at the Details tab there were no details listed. Nothing at all.

So I opened them in VLC player and clicked on Tools>Codec Information. VLC reported the codec as H264 - MPEG-4 AVC (part10) (avc1). That leads me to believe that this is really an mp4 file that has incorrectly been given an .avi file extension.

Would my assumption be correct?

Hello your assumption might be not correct, you must be aware that videos files are in facts files ruled by :

- countainers
- codecs
- bitstreams

Avi is just a countainer that hold a video stream and audio stream encoded by differents kinds of codecs. A codec is more or less, an algorythm process, that compress data in some kind of signal

binary video and video datas are stored and sorted in some way.

Mkv is another countainer, that uses xml techniques to sort diffent kinds of streams.

To be simple .mp4, .mkv, .avi, .mpeg.... are just different way of storing datas in a video file.

a file extension is not sufficient enough to make sure the countainer used is correct. In the past there were great tools for avi files, to see what countainer is really used, the tool was GSPOT

Now it might be old now, but might work

you may use MediaInfo 0.7.64 to see what is really encoded in the file.