Proposal for KDE media interface

Tim Jansen ml at
Tue Aug 5 22:59:26 BST 2003

On Tuesday 05 August 2003 23:06, Morten Hustveit wrote:
> Today I wrote a sample interface for handling media files (audio and video,
> not MIDI) in KDE.  It features raw read and write access, as well as
> playback.  It's intended to have multiple backends, specifically for
> OSS/Free, ALSA and aRts, but more may be added.

That interface does not work with GStreamer and other implementations that 
discover the format's properties as they are reading them. For them you need 
callbacks, signals or a similar solution. Depending on the media type they 
may even change.

Instead of those two hardcoded video/picture formats i would rather have 
FourCC codes or MIME types, which are more flexible (and who knows what kind 
of format tomorrows video cards will take - think XvMC). The audio formats 
lack 4 channel, 5.1, 6.1 and similar newer formats that are used by DVDs, HD 
WMVs and those new CD formats. MIME types would be fine for that as well...

The API does not have a mechanism for reporting the position in the stream. 
When you seek with a complex pipeline it is not always possible to seek 
immediately, this may take some time and the user should be notified about 
the progress (especially with large non-interleaved AVIs). With some formats 
it is impossible to seek to an exact position. Decoders for video formats 
like MPEG do not always allow you to jump to any frame, and some formats do 
not allow seeking at all (Vivo). Seeking to a frame relative to the end 
should be very difficult with many formats, especially those without a 
constant frame rate. The ability to seek may also depend on the KIO module, 
as KIO itself does not support seeking. 


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