[gst-devel] Signals and parsing of files...

Erik Walthinsen omega at temple-baptist.com
Wed Mar 7 21:01:13 CET 2001

On Wed, 7 Mar 2001, Thomas Nyberg wrote:

> Does there already exists an easy way of starting playing at
> arbitrary positions? Or is it a feature yet-to-come?
We have some rudimentary support, but it's going to be re-written very

> One way, would to define a signal that gets emitted when a
> parser/decoder/encoder has enough information for it to be able
> to decode/encode the stream. However, there still exists an issue
> with the amount of information sent to the parser. Too much or too
> little would not be good.
One of the main reasons I decided that an event system was really
necessary is because I realized that some formats have their headers at
the front.  That means that a parser is going to need to be informed when
there's a new file.  That means that if you change the file parameter of
the disksrc, it would send a 'new-file' event down the pipeline, which the
parser could pick up and use to trigger some pre-streaming seek to the

> To start playing in the middle, one could connect to the signal
> described above, and then do a flush/seek-sequence to the
> position in question. But that looks a little bit ugly from
> my point of perspective. There should be a much nicer way
> of doing this. I am sure someone here have thought about it,
> or is thinking about it.
I think as long as the parser is the one that's got all that intelligence,
we're OK.  Parsers are *going* to get ugly, because they have a lot of
responsibilities.  But they are in the best position to do all of this
stuff, because they are fundamentally aware of the media format that
they're dealing with.

      Erik Walthinsen <omega at temple-baptist.com> - System Administrator
       /  \                GStreamer - The only way to stream!
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