[MPlayer-users] Question on conversion of svq1 and wmv files

[Dave Hayes]

[ First off, thank you for your insightful replies. I must point out
  one complication of your request for complete output: I have a message
  awaiting moderator approval because the complete output is too big for
  the list (200K roughly). Is there output I can omit without loss of
  usefulness? ]

rcooley  <RC> writes:
> Dave Hayes <dave at jetcafe.org> wrote:
>> $ /usr/local/bin/mencoder movie1.mov -ovc lavc -oac mp3lame -lavcopts
>> vcodec=flv:abitrate=56 -srate 22050 -mc 1 -ofps 15 -of lavf -o
>> movie.flv
> Is there some reason you're using -mc 1?  I would first try without
> "-mc" at all.  If that doesn't help, try different values for -mc.
> 0/0.01/0.1/10.

Just out of curiosity, why would I do "-mc 0"? 

> Attentive reading of the man page will certainly tell you all of this. 
> The HTML documentation isn't explicit about it, but reading through it
> should still give you a good idea how it works.

My real problem here is that there is little contextually organized
documentation for what I am trying to do. It's all "here's all the
switches" and "here's a few examples". This forces me to hack. 

I have come pretty far from a point of never converting a video before
to understanding that there are multiple streams in video files and
there is a difference between the container and the codecs used inside
the container. However, the specific problems I encounter lack
corresponding contextually grouped and carefully explained
documentation entries.

For example -- I find my video is out of sync. So I dig around and 
find the "-mc" switch  ... here's the man page info:

  -mc <seconds/frame>
   maximum A-V sync correction per frame (in seconds)

Ok. Great! Why is there a maximum, can't I just say "sync this as best
you can"? What's the default? What is this really doing when I invoke
it? :)

Another example -- In trying to use the win32 DLL codecs I see these
two switches:

  -vc <[-]codec1,[-]codec2,...[,]>
   Specify  a priority list of video codecs to be used, according to
   their codec name in codecs.conf

  -vfm <driver1,driver2,...>
    Specify a priority list of video codec families  to  be  used,  
    according  to their  names in codecs.conf.

What's the difference between a codec and codec family? It sounds like
a newbie question (and probably is), but I dont find any explanation
of this distinction anywhere. 

Just to be painstakingly clear: my intent here is at no time to berate
anyone for -not- writing proper documentation. I'm just pointing out
why I'm confused, and pointing to issues in the documentation, in the
hopes that someday these documentation issues (along with others)
might be addressed (or my unwilling ignorance be removed by pointing me
to the correct things to read for these issues).

> RANT:  I've never understood why so many people expect just changing the
> file extension will work.  In my many years of experience using numerous
> programs, I can only recall a handful that will actually change the type
> based on the filename extension (sox/convert/ffmpeg).  Absolutely
> everything else in the world requires you to set a filetype option
> somewhere.

This I do understand.

The philosophy difference between a user and a geek is that we geeks
have a need to specify everything exactly, even if such specification
is redundant and keystroke costly. Users just want to click and have
it "do the right thing" without having to specify options. 

Do you note that in most GUI systems the file extension matters? The
most common example: A GUI makes a different decision about what to
invoke on a double-click based on the extension. This is very common
behavior, especially for GUI centric people, and since we command line
people are rare and outnumbered ... we've had to adopt the above
mindset as the "normal" one.

Even command line software I have had to write for clients, they
expect that I make the "right" decision based on the file extension I
pass them.

I've become comfortable with either methodology, as long as I know how
it works beforehand. 

Ironically, I could very well argue that the default behavior of
writing an "avi" container format in a file you have named
"something.mov" is not very user friendly and could lead to
problems and needless questions. I won't though. :)
------
Dave Hayes - Consultant - Altadena CA, USA - dave at jetcafe.org 
>>> The opinions expressed above are entirely my own <<<

Bribe (n.) - 1. Substitute for law.
Law   (n.) - 1. Substitute for justice.