> If you use libquicktime it should be better.
> When I made some movies with cinelerra I had the following toolchain:
> 
> Raw DV -> gmerlin-transcoder -> QT/JPEG-photo/TWOS -> cinelerra -> 
> QT/JPEG-photo/TWOS ->
> gmerlin-transcoder -> MPEG-2/DVD

makes sense.


> One problem was that cinelerra ignored the pixel aspect ratio of my files.
> So the video was edited slightly squeezed, but in the final transcoding step 
> with
> gmerlin-transcoder I could repair that.

you do know that you can set the aspect ratio that cinelerra uses, right?


> If I make mp4/AAC/H.264 with libquicktime, I can play them with
> Apple Quicktime, vlc and upload them to Vimeo. My version of Apple Quicktime
> (under wine) assumes square pixels though.

I wasn't using gm_transcode at the time, but will from now on.
Cinelerra SAYS it can do mp4/aac/h264   but it really doesn't.  There
are a lot of problems with it.

> > But, that only prints out on stderr on the command line. 
> 
> Not necessarily. In my GUI apps these messages show up in the log window.


I just tried gm_transcode and it wouldn't transcode a file.  The only
error message I got was that that the encoder failed.   This doesn't
tell me much,....however, I'm not so sure there would be a single
problem.  I added a resize filter to the encode chain and it then
worked. 

It would probably take some AI or machine learning to figure out all the
config options and error solutions.  :)


> You can catch the warning messages in your program and ask the user if she
> wants to proceed anyway.
> 
> > Many users
> > don't even know what that is.  How should an application developer
> > notify her user that the container-codec combination is not allowed?
> 
> It can notify if a warning occurred during encoder initialization, that's
> all. If that's because of invalid codecs or something else must be
> irrelevant, because encoding can fail for other reasons as well.

yeah, I see.

> Also there are problems, I cannot catch at all. E.g. there are some illegal
> combinations of H.264 settings. bg_encoder_start() will fail then, but
> there is no generic way to predict it.
> 
> > yes, but that will also limit you to one single stream, correct?  
> 
> No.
> 
> > If you
> > want to stream two parallel videos, what do you do then?  
> 
> Make two encoders. You make as many as fit into your RAM.
> 
> > Or, if you
> > want to encode in two different formats and write them to disk using the
> > same media input, one would have to know how to manipulate the config
> > and plugin registry, correct?
> 
> Yes.
> 
> I see that manipulating the config section is not trivial for 3rd party
> apps. I never had the problem because I programmed the config registry
> together with the gtk widgets. Actually the config system was the first
> module I wrote for libgmerlin, because all other modules configured with
> it.
> 
> An important point is that the config system has *no* idea of what the
> parameters actually mean, if they are codecs or whatever. It's my
> general strategy that one module knows as little as possible about the
> others. All communication works through simple and *generic* interfaces.

this is good, I think.   I just need to learn the interfaces :)

> Advantage is that modules can be combined almost arbitrarily (IMO
> libgmerlin can be compared to a huge bunch of Lego bricks). Also
> firing up a configuration dialog is a few lines in C. And it doesn't
> matter if I configure a bg_encoder_t or a filter chain or GUI colors.
> Once a parameter setting mechanism is in place, things become extremely
> simple.
> 
> Disadvantage is, that e.g. my encoder has no way to generically set a
> "codec", "container", "bitrate" etc. The encoder configuration just has a
> nested structure of parameters, whose values are in a nested structure
> of bg_cfg_section_t's.

> I would really like to make the stuff easier to use and I'm sure that
> presets are a first step for this. But that won't happen before the
> release is out, and for releasing I need to make sure that no serious
> bugs are left. So my priority is now to fix the remaining
> problems in encoding plugins.


of course.  It seems like we were able to squash a few bugs here an
there ..so cheers for that! 

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