On Mon, Oct 01, 2001 at 10:45:54AM -0600, Warren Young wrote: > Yes, ANSI has these docs, and they will let _you_ have a copy for about > $400. That's for the first three sections, which are the main ones. > (System, video and audio.) http://webstore.ansi.org/ Search for ISO > 13818, sections 1 through 3.
Gah. How wonderful to have open standards that cost money. > For this simple task, you might find a copy of the Mitchell book more > approachable. It can be had for about $120. It doesn't replace the > MPEG standards, but it's a whole lot easier to read. Maybe I can skim it at Barnes and Noble... > You might do it that way, but usually you chop out the whole GOP, > including the associated I frame. In other words, while you can leave > an I frame in the stream alone, you usually want to chop whole GOPs out. Okay, cool. I was under the impression that the B and P frames might forward-reference a starting I-frame. But GOP boundries makes sense. > > (I realize that it's actually IPBBPBBPBBI.) > > Actually, that's the playback view. In the stream itself, the frames > are given as IBBP.... "playback"? Or decode view? The _visual_ playback should be IBBP, right? (And, by the way, if the decode view is IPBB, why isn't the stream IPBB?) > You will also need to know how to parse MPEG-1 audio layer "frames". > The Mitchell book has almost nothing to say about MPEG audio. Luckily, > there is a whole lot of free MPEG audio code out there which you could > study. Agreed. I have a simple task, IMHO, but I can't do it without format information. > For Windows, yes. Visit the link below and see the MPEG editing article > for info on that subject. None of the programs mentioned work on Linux, > however, which I assume is your aim since you're posting here. > = MPEG articles: http://tangentsoft.net/video/mpeg/ Ah, yes, this is exactly the kind of article I was looking for. So, the formal description is "I want to write a GOP-accurate MPEG editor for linux." :) Now, if I "reverse engineer" the MPEG formats I'm interested in, and "publish" this documentation, will ISO trying to beat me up? Because I can't believe I'm the only person trying to find details on MPEG file formats. Thanks! -- Kees Cook @outflux.net
