container formats and "regular" formats

[JWorld]

Hey, everyone

I am working on a project that requires some background in multimedia manipulation.

But the various formats and one other so-called container format seem very confusing.

What I have understood so far is that CONTAINER formats don't really have anything to do with the compression and decompression algorithms used for specific the audio and video data, they are just wrapper formats that specify how various components, such as sound and images, of the file would synchronize whith each other. It might also include something else like the chapter info on a DVD, but not about codecs. Therefore, two files of the same CONTAINER format might actually require two totally incompatible codecs.

Now my question is
IS MY UNDERSTANDING WRONG?

I believe MPEG-4 is a container format. So there would be really no point to say a file is in mpeg-4 format, BECAUSE this does not provide information of what specific codec to use if we want to actually play it. Is it correct?

And yet, I have seen plenty of multimedia files which claim to be in mpeg-1, mepg-2, mepg-4, or AVI formats. All these I believe are container formats. Is this a wrong practice or it has some other meanings.


thanks, i am so desperate for your helps

 

[Nelviticus]

Your understanding of the first part is correct. Beyond that my own understanding gets a bit flaky, but I do know that MPEG 1 and 2 are compression formats and I believe that MPEG 4 is also a compression format.

The Wikipedia site for video codecs is a good place to start for more info.

Regards

Nelviticus

 

[felixc]

Being a container format or not, I don't see what makes it a problem to you.

Mpeg 1-2-4 are compression algorithms. Avi is unfortunately a generic name used by different formats. Mpeg-4 files can have an avi extension. Divx files too. These Mpeg formats can address different resolutions and compression levels. Variatons of these formats are also found in digital broadcast video, where the different broadcasters use different algorithms to squeeze as much contents as possible in a an allocated bandwidth slot.

But anyway I don't see what makes your life difficult. You need to know what your equipment can generate, what your editing system needs, and make sure that you are not scrapping the quality of the original video contents. You can look at it from an easy point of view or you can drown under details. Talk to a knowledgeable person around you, and just concentrate on the results that you need. Digital video comression algorithms isn't a hobby.