Original commit message from CVS:
Another big set of changes. Connections are now also pullfunc based.
gstqueue has been updated, I don't know of any other connections offhand.
There are still a few things that need doing, specifically the concept
of a source or connection with connections to multiple thread contexts is
not dealt with. This may force us to move the threadstate from the
element to the pad, maybe keeping the element's copy for simple cases.
Then the Bin would create a structure to pass to the cothreaded _wrappers
of any such elements, which would detail the pads that are to be dealt with
by this particular cothread context.
That will speed things up to, since we don't have to look through the list
of all pads for every Src or Connection element for every iteration, we can
simply step through the list provided by the plan. Special case might even
have a single pad pointer sitting there to trump the list, if there's only
one (the common case anyway).
Task 23098 is tracking these changes. The main task 22588 depends on that
subtask, as well as 22240, which is a consistency check on PAD_DISABLED.
Original commit message from CVS:
Changed the way things are scheduled, especially sources. A Src used to
have a push() function, and optionally a pushregion() to deal with async
reads, etc. That whole thing has gone away, in favor of providing a
pull() function for the output (Src) pad instead, ala chain functions.
This makes constructing cothreaded schedules out of non-loop elements
somewhat easier. Basically there was always a question as to which pad
was being dealt with. In the pullregion case, cothread-specific data was
used to try to pass the region struct to the right place, which is a slow
hack. And in general, the push function severely limited the kind of
tricks that could be played when there's more than one output pad, such as
a multi-out file reader with async capabilities on each pad independently.
This changes the way cothread scheduling occurs. Instead of the hack to
deal with Src's by calling their push() function (or optionally the
pushregion(), in certain cases), we now are working towards a general
mechanism where pads are the only thing that are dealt with directly.
An optimization was made in the process of doing this: the loopfunction
actually run as the outer [stack] frame of the cothread is now set more
intelligently in create_plan() based on what kind of element it is. We
now have:
loopfunc_wrapper: used for loop-based elements, it simply calls the
loopfunc in a loop, paying attention to COTHREAD_STOPPING (see
below). It currently does other, soon to be depracated, stuff.
pullsrc_wrapper: wraps a Src that's not loop-based (since your options
are now loop- or pull-based)
There will be a couple more to deal with other cases, such as Connections
and chain-based elements. The general idea is that it's a lot more
efficient to make the decisions once in create_plan than to keep doing
this huge if/else chain in the wrapper. Just choose the right wrapper up
front. It'll be most apparent performance-wise in the case of whichever
element context is switched to first for each iteration, since the whole
wrapper setup is done for every iteration.
The tricky part is that there is now a bit of overloading of the function
pointers in a pad. The current meanings (possibly to change a bit more
soon) are:
chainfunc: as always, chainfunc pointer is mirrored between peer pads
(this may change, and the chain func may end up in pushfunc)
pushfunc: SrcPad: gst_pad_pushfunc_proxy, cothread_switch to peer
SinkPad: none (may take over chainfunc, see below) pullfunc:
SrcPad: Src or Connection's function to construct buffers
SinkPad: gst_pad_pullfunc_proxy, cothread_switch to peer
There are a number of issues remaining with the scheduling, not the least
of which is the fact that Connections are still dealt with the old way,
with _push() functions and such. I'm trying to figure out a way to unify
the system so it makes sense. Following the scheduling system is hard
enough, trying to change it is murder.
Another useful scheduling addition, mentioned above, is COTHREAD_STOPPING.
It's an element flag that's used to signal whatever code is running in
cothread context that it should be finishing up and exiting soon. An
example of this is in plugins/cobin/spindentity.c. All the loops should
now be composed of do/while loops, rather than while(1) loops:
do {
buf = gst_pad_pull(spindentity->sinkpad);
gst_pad_push(spindentity->srcpad,buf);
} while (!GST_ELEMENT_IS_COTHREAD_STOPPING(element));
The reason for this is that COTHREAD_STOPPING may be set before the above
loop ever gets started. It wouldn't do for the body of the loop to never
once get called, that would simply stall the pipeline. Note that only the
core library code is ever responsible for setting and unsetting this flag.
All elements have to do is respond to it by cleanly exiting the loop and
the function holding it.
This is needed primarily to allow iterations to occur properly.
Basically, there's a single entry point in the cothread scheduling loop,
gst_bin_iterate_func() simply switches to this cothread. If the element
in this context is allowed to loop infinitely, nothing would even switch
back to the context from which the iterate() was originally called. This
is a bit of a problem. The solution is for there to be an implicit switch
back to the originating context. Now, even I'm not sure exactly how this
works, but if the cothread that's switched to actually returns, execution
returns back to the calling context, i.e. iterate_func().
COTHREAD_STOPPING is therefore set just before switching into this
(currently randomly chosen) context, on the assumption that it will return
promptly after finishing its duties. The burden of clearing the flag
falls to the various wrapper functions provided by the Bin code, thus
element writers don't have to worry about doing that at all (and simply
shouldn't).
Related changes:
All the sources in elements/ have been changed to reflect the new system.
FIXMEs:
1) gstpipeline.c calls gst_src_push at some point, dunno why, it's
commented out now.
2) any other sources, including vcdsrc, dvdsrc, and v4lsrc will break
badly and need to be modified to work as pull-based sources.
Original commit message from CVS:
gstbin.c: modified so create_plan occurs after the state change of all the
child elements.
gstelement.c: set_state now loops such that each element only deals with
one state change at a time, i.e. NULL->READY,READY->PLAYING,
instead of a single NULL->PLAYING.
Original commit message from CVS:
Docs updates.
Added LICENSE info to headers/code where missing in gst directory
Added a bonobo wrapper for the media player (it shows up in gshell but
locks up when activating the component, anyone?)
Fixed some XML save/load problems with arguments.
Original commit message from CVS:
Added seeking to the avi decoder by implementing pull_region.
Fixes to the asyncdisksrc.
Added thread specific data to the cothreads.
Original commit message from CVS:
Misc fixes and cleanups
A reworked gstplay. Now it is called gstmediaplay. gstplay is a custom
widget that can display media and is to become a bonobo component soon.
put the tables of the mpeg audio encoder in a header file.
maybe faster quantisation for the mpeg encoder.
Original commit message from CVS:
Fixed a bug in the typeloading.
Fixes to various elements so that correct types are returned.
Fixed flag collision with GtkObject.
Elements can now suggest a thread. not sure if this is the right way to
handle automatic thread creation.
Autoplugging now works with multiple sinks and thread setup. No threads
are created for intermediate elements yet, so MPEG may still be choppy.
Original commit message from CVS:
Loading and saving of XML pipeline descriptions.
GladeXML like operation implemented (you can retrieve parts of a pipeline)
Original commit message from CVS:
The cothreads were not initialized in its thread context resulting in
severe stack corruption. This was very hard to track down.
We should be able now to modify some plugins to a loop based setup so that
we can get rid of the mp3parse and mp1videoparse elements.
Modified the GList to a GSList in the queue.
Original commit message from CVS:
A first attempt to fix the queues in a cothreaded pipeline.
Some fixes to the thread handling.
Fix a bug in gstreamer-config : gthread was not included.
gst_bin_create_plan() is now done in the READY state.
a bin with only another bin in it will now work with gst_bin_iterate.
Added some examples for the queues.
Original commit message from CVS:
Added gst_pipeline_add_sink/src to allow multiple sink cases and
more complex autoplugging. Update docs too.
Simplified the pipeline autoplugging code.
Changed the cothread case: One iteration is now a push from the src
element. The disk source does not change its state anymore on eof.
Better type setting for the ac3 parser/decoder and mpeg2parse.
Original commit message from CVS:
Added check for vorbis.
Really compile with Xv extension if the library is found.
Changed the disksrc so that is goes to the PAUSE state if eof.
Original commit message from CVS:
Added a quick hack to allow loop based elements to finish intead of
looping till infinity.
Added compile time i386 or plain C getbits implementation selection.
The vorbis decoder now is our first loop based element!
Original commit message from CVS:
Due to popular demand :-), I added a vorbis decoder.
The encoder is not yet functional.
Small cosmetic changes to gstcpu.c
Beware:
You *need* to install libvorbis.a from the main vorbis CVS.
you *have* to change the line in libtool to
deplibs_check_method="pass_all"
because else the plugin shared library refuses to link against the
static libvorbis.a library. This is a hack. I have no intention in
including libvorbis into the gstreamer CVS tree and making it
libtool compatible.
Original commit message from CVS:
Faster and modular getbits implementation.
Fixed a bug in the audiosink that could lock up your box on bad MB.
Modified the plugins to use the new getbits functions.
Original commit message from CVS:
A first (rude) attempt at autoplug.
Autoplugging selects appropriate codecs to connect src to sink, adds
them to the pipeline and connect pads.
Autoplugging will run the typedetect plugin if the src pad has no MIME
type.
No autoplugging is done on the src and sink pads, it's hardcoded:
connect 'src to sink'.
No attempt at creating threads.
No attempt at dynamically autoplugging not yet existing pads.
Changes to (some) plugins to properly set their MIME types.
Original commit message from CVS:
Megapatch, changes which states are available, how they're used, and how
they're set. Also modifies the scheduling system, breaking pulled
buffers. Check mail archives for more details.
Original commit message from CVS:
This is the audio/video sync release.
Changed the mpegvideoparser to parse complete pictures. Added the PTS
timestamps to the pictures.
Added PTS timestamps to the MPEG audio frames.
Made the clock a littlebit better.
Gstplay now uses two more threads one for video, one for audio playback.
Added the first QoS callbacks for the pads.
hopefully fix an mmx compilation problem.
Original commit message from CVS:
Documentation updates. All standard library objects and standard
elements are documented. Modified some of the elements to more
accuratly report about their arguments so the documentation builds
more reasonable output.
Added aviencoder and jpegencoder elements (not working yet)
Original commit message from CVS:
This is a rather large patch. Switched on -Wall compiler flag and fixed
the warnings.
Made the Video for Linux more like it should be.
Original commit message from CVS:
Changed the way state is dealt with when a child is added to the bin. The
note states that the COMPLETE state should probably reflect nothing more
than whether or not there is a child in the bin, not whether or not all
children are COMPLETE. I need to write out a few scenarios for complex
pipeline manipulations to figure out how all the states should interact.
The idea is to maintain the ability to dynamically recofigure the
pipeline.
