Re: New: Type inheritance and conversion parameters

["Kenneth Christiansen" <kenneth christiansen openbossa org>]

Great to hear John,

I will have a look at it today or in the beginning of the next week.
Thanks a lot for the hard work!

Cheers,
Kenneth

On 10/31/07, John Stowers <john stowers gmail com> wrote:
>
>
> On 9/15/07, Kenneth Christiansen
> <kenneth christiansen openbossa org> wrote:
> > Hi John,
> >
> > Sounds pretty nice, and this is definitely something that we need. I guess
> you probably want a way for the user to define what to use to do the
> conversion, especially when it comes to videos (many use mencoder for N800).
>
> All of this should now be implemented in SVN. Transcoding and better nokia
> n800 support. In addition there should be no hard dependence on Gtk
> remaining in the Conduit core.
>
> I would appreciate your thoughts on these changes and how we can continue to
> work together - canola, syncronization, syncropated, conduit and nokia - one
> big family!
>
> See
> http://www.johnstowers.co.nz/blog/index.php/2007/10/31/one-thousand/
> for more info
>
> John
>
> > {"size":"640x480"} mean that the images will be resized to fit within the
> size of 640x480? or will they be scaled until one side fits and then
> cropped? or maybe that should be an option.
> >
> > Cheers,
> > Kenneth
> >
> >
> >
> > On 9/13/07, John Stowers < john stowers gmail com> wrote:
> > >
> > > Hey Team
> > > When I get internet at home in a few days I am going to do a rather
> large commit introducing type inheritance and conversion parameters. I will
> explain what these are, and how we should use them.
> > >
> > > Motivation:
> > > We have kind of hit a wall with the type conversion stuff, there is
> (currently) no sane way in the conversion framework to transcode media,
> resize photos, or other use cases where the general type remains the same,
> but something else about it changes. I want to improve the usefulness of
> conduit to media dataproviders. The $FUTURE_STEP after this stage is to make
> converters objects, and not static functions, but that can be done later.
> > >
> > > Lets start with a contrived example
> > >
> > > class File(DataType):
> > >     _name_ = "file"
> > >     def __init__(self)
> > >         pass
> > >
> > > class Photo(File)
> > >     _name_ = "file/photo"
> > >     def __init__(self)
> > >         pass
> > >     def get_image_size(self):
> > >         pass
> > >
> > > Note: _name_ specifies the named type. This used to be an argument to
> the base constructor.
> > >
> > > Dataproviders may now implement a function call
> get_input_conversion_args and/or get_output_conversion_args which returs a
> dict of parameters to be passed to the conversion function
> > >
> > > class FlickrSink
> > >     _in_type_ = "file/photo"
> > >     def get_input_conversion_args(self)
> > >         return {"size":"640x480"}
> > >
> > > Lets say the user wants to sync a folder of photos with Flickr. Folder
> out_type = "file" and Flickr _in_type_ = "file/photo". Converters now have
> configuration arguments. For example
> > > converters = {"file,file/photo":convert_file_to_photo}
> > > def convert_file_to_photo(file, **kwargs)
> > >     t = file.get_mimetype()
> > >     if t != jpeg:
> > >         return None #may return None if a conversion is not sensible
> > >     p = Photo(URI=f.get_URI())
> > >     p.resize (kwargs["size"])
> > >     return p
> > >
> > > In the two way sync case, such as Flickr <-> Folder, the conversion from
> photo_to_file is not needed becase photo is a subclass of file.
> > >
> > > Imagine syncing Rhythmbox to your n800, you want to encode the audio to
> a lower bitrate. In this case you define a transcode function, which is
> realy just a function that converts a type to itself.
> > >
> > > converters = {"file/music,file/music":transcode_music}
> > > def transcode_music(music, **kwargs)
> > >     return
> music.transcode(kwargs["format"],kwargs["bitrate"])
> > >
> > > Anyway I would appreciate your comments on this new functionaliy, thomas
> does this make sense in the image case. Obvioulsy the pseudo code above
> contains no error handling but is how I envision the data flow.
> > >
> > > Jc2k, how is that gstreamer transcoder going?
> > >
> > > John
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > Conduit-list mailing list
> > > Conduit-list gnome org
> > > http://mail.gnome.org/mailman/listinfo/conduit-list
> > >
> > >
> >
> >
>
>