On Sun, 29 Oct 2006 19:50:11 +0200
Wolfgang Wershofen <wolfgang@...> wrote:
> You don't have too much knowledge of DVD authoring, right?
Apparently, but then again, when it really comes down to it, who does? ;)
> The DVD specification forces the contained vob files not to extend
> 1 GB filesize. dvdauthor takes your input stream and creates those
> chunks for you but for your dvd player, it's still only one big stream.
I am aware of this. However, sometimes it would be nice to be able
to divide a VOB and have the chapters marked off according to these
VOBs rather than timestamps. For example, it would then be easy enough
to approximately divide a stream into say, tenths, even when the
running time is not exactly known.
What gets me is that those "output" VOBs on the DVD are broken in what
appears to be mid stream and yet play seamlessly. But, as you mentioned,
their boundaries are not marked as "chapters".
> The original DVD had the chapter definition in the IFO-File (AFAIK).
> With the way, you extracted it, you got only the mpeg stream and
> not the dvd navigation structure. Why do you use this brute force
> attack at all and not give dvdunauthor or other dvd ripping
> solutions (there are many!) a chance?
Because as I mentioned, the original structure causes my player to
crash. Also, don't get me started on "SCR moves backwards".
We may have sparse DVD authoring tools for Linux, but it seems that
many Windows folks have tools that are just plain broken.
To the credit of the open source authors, I have found that DVDs authored
with dvdauthor are more robust with respect to player compatibility than
many DVDs that were produced using commercial products.
> Because in most mpeg files, the video and audio tracks are not
> exactly of the same length. So, at the end of an mpeg file, either
> the audio or the video stream has to wait for the other to finish.
Does the player enforce this at chapter breaks, even though the
different VOB files themselves form an "unbroken stream"?
> Another point is how you divide your movie in chunks. It is most
> likely that you leave an incomplete GOP at the end and/or beginning
> of a file and this GOP (12-15 pictures) will be discarded by your
At 0x00 0x00 0x01 0xba .... 0x00 0x00 0x01 0xbb break points, dvdauthor
does not complain about skipped sectors looking for a VOBU or
unclosed GOPs. I think this sequence marks the start of a "VOBU", so
I am not breaking within VOBUs. However, I now see that although
video is padded at the end of each VOBU, audio is not. So, audio
frames can span multiple VOBUs. Dang it.
> The 1GB VOB-Files of a dvd are created by a piece of software
> that knows how a dvd player works and those files are linked
> together in the DVD navigation information - to put it in simple
Suppose that we have two VOBs that are divided "properly". Are you
saying that if I feed these into dvdauthor as two different files,
that I can indeed have seamless transitions between them? I would
love it if someone conducted an experiment to see. I should point
out that the skip is not noticeable in the software player I've
tried. I don't know about other hardware players.
> You don't need to use the xml to specify chapter breakpoints.
> It seems, you don't spend too much time in reading documentations
> and help texts.
Not from my perspective. ;) IMHO, few applications in Linux history have
more disparity between the capability of an application and its available
documentation than dvdauthor.
> By issuing "dvdauthor -h" you may find the following:
> --chapter[s][=COPTS] or -c COPTS or -C where COPTS is a comma (,)
> separated list of chapter markers. Each marker is of the form
> [[h:]mm:]ss[.frac] and is relative to the SCR of the next file
> listed (independent of any timestamp transposing that occurs within
> dvdauthor). The chapter markers ONLY apply to the next file listed.
> COPTS defaults to 0
> So simply put -c with a list of timecodes before your input mpeg file and
> dvdauthor creates perfect chapter transitions withour any hickups.
ahhh, need I point out that this is not covered in the dvdauthor man page
nor in the "official documentation" at:
My only hint in the man page is "-c chapterpts". This is the first time
that I've seen an application's usage help message be more informative
than its man page.
> If you find a solution, how your mpeg stream can be splitted without
> producing incomplete GOPs at the transitions points and that the
> resulting mpeg streams will have video and audio streams of exactly
> the same length, then dvdauthor will create perfect chapter transiitons,
Are you really, really sure about this? As I said, I am pretty sure that
I am not breaking VOBUs or GOPs. Are you sure that dvdauthor is doing,
or is not doing, something that can prevent the seamless playback of
even correctly broken VOBs when they are fed in on the command line?
I guess my problem is with the audio frames that span multiple VOBUs.
But, I'd sure like to know if anybody has ever done a:
dvdauthor -t -o outdir *.VOB
and ever got seamless playback this way.
> But I'm afraid, there isn't such a solution... At least I haven't
> seen any yet...
What about vobwalker?:
which breaks according to cells? I have not tried it yet though, but
I think the cell level is not very fine grained. Maybe I'll give it
a try and let you know what happens.
Could you tell me any good sources (even on paid basis, except for
the official standards themselves) of information on the VOB