[gstreamer-bugs] [Bug 583098] Add jpegparse element

[GStreamer (bugzilla.gnome.org)]

http://bugzilla.gnome.org/show_bug.cgi?id=583098



--- Comment #8 from Arnout Vandecappelle <arnout at mind.be> 2009-08-25 13:45:56 UTC ---
(In reply to comment #7)
> (In reply to comment #6)
> > In fact, is
> > there a reason not to split it into two elements, one for parsing and one for
> > caps?
> 
> I don't know. I don't get why it should be split. A gstpjpegpacketize and a
> gstjpegparse ??

Splitting because they have somewhat orthogonal functionality.  The packetiser
splits a continuous stream into single-frame buffers, the parser analyses caps.
 The reason to split is because you may need one but not the other.  E.g., if
the stream comes out of a demuxer or rtp, it is already packetised but perhaps
caps are not set correctly yet (e.g. rtpjpegdepay sets w/h but not format - not
that I think the format is actually useful).  On the other hand, if you just
want to packetise and don't care about the metadata (e.g. because you'll just
send it to a decoder that doesn't packetise itself), the scanning of the
headers is redundant work.

In addition, if you set the 'parsed' property on the source/sink caps to enable
autoplugging of the parser, then it is no longer possible to create a pipeline
like rtpjpegdepay ! jpegparse (assuming rtpjpegdepay also sets the parsed=true
property).  If jpegpacketize and jpegparse are split up, you could still create
a rtpjpegdepay ! jpegparse pipeline (but not the useless rtpjpegdepay !
jpegpacketize pipeline).


> Btw, what are your feelings about using gstbaseparse (bug 518857) ??

I'm completely in favour of using base classes, but I didn't realize a parser
base class existed when I wrote the element.  I was basing myself on
mpeg4videoparse which doesn't use the base class (yet).

I noticed now that gstbaseparse also assumes packetising and parsing are done
together, so I guess my statements here do not reflect the general feeling of
the community.

-- 
Configure bugmail: http://bugzilla.gnome.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
You are the assignee for the bug.