[MPlayer-dev-eng] Make dvd-compatible mpeg's and keyint (gop size)

[Oded Shimon]

On Thu, Sep 29, 2005 at 03:12:09PM +0600, byavl wrote:
> What exactly ? mpeg-4 has smart defaults, but what dvd ?
> Is it good practic when I must to explore all options
> because your defaults is out of standarts ?
> You suggest to specify all options. Say no if I say it is stupid!
> Default means values that decrease preparing time and
> save from mistakes.  In your case it is not!
> I expect to get good result without investigation all kind of your
> defaults even if I know many dvd specific terms.
> It is cool if you can operate with mpeg options.
> Talk about to other. But in accurate form.
> Manual has no intelligible description
> how to do mpeg2 and DVD compliance materials.
> Are you try using 'transcode' ? Same problem.
> Work correctly only for special prepeared materials.
> And after above you speak mplayer is the best!
> I'm agree mplayer very good application.
> But mencoder not.
> 
> Furthermore for my case no any debug output about gop size.
> In one mailing list anyone talking about verbose option...
> I say about - many garbage, not to groups,
> very unuseful.
> For current techical debug maybe useful, but for daily
> operating it is not.
> 
> 
> In addition what you can say about many SIGSEGV
> that happens very often when using mpeg2video ?
> I think - nothing news again.
> 
> About vrc settings. If one is omited the result mpeg
> is bullsheet. So, where is default ? Where is any warnings ?

It's not bullshit, it's still a completely valid mpeg-2 stream, it's just 
not a valid _DVD_ stream, because the DVD specification is VERY (studpidly) 
strict, the values requested by the standard increase bitrate and lower 
quality A LOT, so making them default, when using MEncoder is usually for 
making high quality low bitrate MPEG-4 streams, not DVD, is just not 
sensible!!

MEncoder is a command line tool, it's purpose is not to be friendly, but to 
be powerful. If a (l)user wants to create a compliant DVD, he should check 
the documentation (see DOCS/HTML, there's a COMPLETE guide there about DVD 
compliance, including command line examples) to do it right, or use a smart 
frontend which already does the settings for him...

> By the way I'm programmer in linux about 15 ages and one
> think about all above - DVD is not intresting for you.
> mpeg-4 it is cool for you, but is is last age...
> Or may be it is laziness.

MEncoder was originally an MPEG-4 creater, creating valid DVD streams is a 
VERY recent new feature in MEncoder, and it's even a hack... And, well, the 
default has to be picked for SOME direction, it being towards MPEG-4 makes 
more sense as it is more popular to use MEncoder for MPEG-4 than for DVD.

If anything, one thing that does make sense is possibly adding this 
feature:
-lavdopts preset=dvd

or similar, but I'm not sure if that's such a good idea.

- ods15