Kees Cook writes: > 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! > > --
I have a primitiv MPEG cutting program in the mpegtools that come with the DVB card drivers at linuxtv.org. You can give it a filesize and it will cut the MPEG file along GOP boundaries into the approximate size. In the code you can see how to find the boundaries. I don't do anything special for sound, just trusting in good enough muxing :). Marcus -- --------------------------------------------------------------------- Dr. Marcus Metzler [EMAIL PROTECTED] http://www.metzlerbros.de [EMAIL PROTECTED] http://www.convergence.de Convergence Integrated Media GmbH Rosenthaler Str. 51 D-10178 Berlin ---------------------------------------------------------------------
