Thread

Teach me about video formats

· Troubleshooting · 5 posts · Apr 19, 2005 — Apr 20, 2005 View original thread ↗

#1 Tue, 19 Apr 2005 - 14:01

My cousin stopped by last night with some VHS footage of his band playing some songs. He wanted me to use my ADVC converter to capture the analog footage. I captured it in iMovie, cropped and added transitions, titles, and iDVD chapter markers. This is all stuff I had done before, and so I felt like I knew what I was doing. I saved the movie and created an iDVD project, burned the DVD and everything was ok.

But in addition to the DVD, my cousin wanted me to give him the video as two separate mpeg2 files, so that he could convert them to WMV format (he's a Windowser) and put them on the web. Now, I could do that as a Quicktime web export in iMovie, no problem. But when I started trying to figure out how to export as mpeg I realized I don't know squat about video formats.

My question is this... What makes Quicktime and WMV and Divx different formats if the file you export is encoded in MPEG4? What makes an AVI an AVI if there are all different kinds of ways to encode it? If you have a 'video.mpg' file that is neither Quicktime or WMV, what is it? Can someone break it down for me as to how the file format vs. encoding format stuff works?

TIA

#2 Tue, 19 Apr 2005 - 17:18

You won't want to encode to MPEG2 and then to WMV. Just give him the DV files directly, and he can encode to WMV from there. If you are willing to spend ~$50, you can also buy a Quicktime export component for WMV, so you could get to WMV directly from iMovie. But even better would be to encode to a standard, like MPEG4.

Quote:

What makes Quicktime and WMV and Divx different formats if the file you export is encoded in MPEG4?

Quicktime's .mov is a container. It can contain a number of different audio/video codecs, including MPEG4. WMV is a codec, but it is also generally tied to the Windows Media container. It is not MPEG4, though older versions were similar to MPEG4. Divx is an MPEG4 codec, which most people put into an AVI container.

Quote:

What makes an AVI an AVI if there are all different kinds of ways to encode it?

AVI is just a container. It can contain a number of different codecs.

Quote:

If you have a 'video.mpg' file that is neither Quicktime or WMV, what is it?

It's supposed to be MPEG1. Just like if you come across an MP4, it's supposed to be MPEG4.

#3 Tue, 19 Apr 2005 - 20:29

Thanks for the great info. Thinking about the different formats as containers makes sense. And I'm sure there are advantages/disadvantages to the different containers. I know I more commonly have problems watching streaming wmv video than quicktime video, even on Windows PCs. They commonly just stop in the middle of the stream and won't rebuffer. Quicktime files online rarely have that problem.

So since you could save a MPEG4 encoded file within a .mov container, or within an .avi container, does that mean that a file saved as .mp4 has no container?

Quote:

Originally Posted by bmedina

You won't want to encode to MPEG2 and then to WMV. Just give him the DV files directly, and he can encode to WMV from there.

That was actually the first thing we tried. Windows Movie Maker couldn't import the file (not surprisingly) and even Quicktime player couldn't play it (surprisingly). I didn't export the file though, I just dragged it out of iMovie as a .dv clip and over to his laptop.

#4 Wed, 20 Apr 2005 - 01:10

This is still mostly up to date I think, but it's not specific to your question and won't tell you how to encode WMV:

http://forums.macnn.com/showthread.php?p=2414670

Quote:

Originally Posted by jasonsRX7

So since you could save a MPEG4 encoded file within a .mov container, or within an .avi container, does that mean that a file saved as .mp4 has no container?

No, mp4 is a container too. Actually, "mp4" is just a container and "mpeg-4" is just a codec (actually "mpeg-4" also other things you don't have to worry about). It's confusing. The only thing I know of that's just a raw bitstream with no container is .xvid, and you never see that in the wild. It's possible .m1v/.m2v/.mpv are raw bitstreams; I give that a 50% chance. You never see them either.

Quote:

I just dragged it out of iMovie as a .dv clip and over to his laptop.

I don't know how iMovie handles drag and drop, but in QTPlayer that would just create a reference movie (a small file that's dependent on the original, wherever iMovie stores that). How big was the file you dragged to his laptop? DV is always fixed at the same bitrate, about 13 GB per hour; that's the first clue you have to find.

#5 Wed, 20 Apr 2005 - 07:45

Quote:

Originally Posted by Uncle Skeleton

The name of the iMovie project was jeff, and when I dragged the clip in its entirety to my desktop, it created a 'jeff.dv' file that was 2.33gb in size, but it had a "blank page" icon instead of the icon that would indicate that it was associated with Quicktime. When I opened the jeff.dv file on my Mac, it would play in Quicktime player. On his PC laptop it wouldn't, even when manually going thru File -> Open and picking the file.

Last night I tried something else. I selected the clip in the timeline and exported it via the 'Share' function and saved it as full quality Quicktime. This created a file called jeff.dv but this file had the Quicktime icon associated with it, and was the same 2.33gb in size. I copied it over to my PC and it opened in Quicktime player. Movie Maker still couldn't import it, but I'm sure there's some freeware conversion program available.