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773c1e4c1d
Original commit message from CVS: * docs/design/part-TODO.txt: Mumble something about removing GstXML.
102 lines
4.7 KiB
Text
102 lines
4.7 KiB
Text
API/ABI
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-------
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- implement return values from events in addition to the gboolean. This should
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be done by making the event contain a GstStructure with input/output values,
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similar to GstQuery. A typical use case is performing a non-accurate seek to a
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keyframe, after the seek you want to get the new stream time that will
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actually be used to update the slider bar.
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- make gst_pad_push_event() return a GstFlowReturn so that we can resend
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NEWSEGMENT and other events.
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- GstEvent, GstMessage register like GstFormat or GstQuery.
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- query POSITION/DURATION return accuracy. Just a flag or accuracy percentage.
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- add some sort of time/frame stepping functionality, either with a flag on
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the seek event or some new seek event type. The idea would be to operate on
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the current playback position instead of the current configured segment when
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doing the seek.
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Idea is that frame stepping forwards can be done in the sinks, ie, just
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dropping N frames/time, sending more complicated queries upstream which can
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ideally handle those cases more efficiently too. Some ideas are in
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docs/design/draft-framestep.txt
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- use | instead of + as divider in serialization of Flags
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(gstvalue/gststructure)
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- rethink how we handle dynamic replugging wrt segments and other events that
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already got pushed and need to be pushed again. Might need GstFlowReturn from
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gst_pad_push_event().
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- keep track of seeks with a counter so that we can match seek events received
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in the demuxer srcpads. This is needed because a normal seek on a pipeline
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will send the seek event on all sinks, which results in the demuxer receiving
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the seek twice. If there is no way to see that the seek is the same, it will
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perform the seek twice.
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It would also be nice to have this same sequence number in the segment event
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that resulted from the seek so that everything seek related can be tracked
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properly.
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- Optimize negotiation. We currently do a get_caps() call when we link pads,
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which could potentially generate a huge list of caps and all their
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combinations, we need to avoid generating these huge lists by generating them
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incrementaly when needed. We can do this with a gst_pad_iterate_caps() call.
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We also need to incrementally return intersections etc, for this.
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- When an element goes to PAUSED there is no way to figure out the running time
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when this happened. One could think that we can store this time in the
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base_time field of the element but that causes problems when the element is
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still using the base_time before really PAUSING. We seem to need a new element
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field for this. The running time when an element is paused can be usefull to
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clip late buffers instead of prerolling on them.
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- Elements in a bin have no clue about the final state of the parent element
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since the bin sets the target state on its children in small steps. This
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causes problems for elements that like to know the final state (rtspsrc going
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to PAUSED or READY is different in that we can avoid sending the useless
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PAUSED request).
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- Make serialisation of structures more consistent, readable and nicer code-wise.
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- pad block has several issues:
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* can't block on selected things, like push, pull, pad_alloc, events, ...
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* can't check why the block happened. We should also be able to get the item/
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reason that blocked the pad.
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* it only blocks on datapassing. When EOS, the block never happens but ideally
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should because pad block should inform the app when there is no dataflow.
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* the same goes for segment seeks that don't push in-band EOS events. Maybe
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segment seeks should also send an EOS event when they're done.
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* blocking should only happen from one thread. If one thread does pad_alloc
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and another a push, the push might be busy while the block callback is done.
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* maybe this name is overloaded. We need to look at some more use cases before
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trying to fix this.
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- rethink the way we do upstream renegotiation. Currently it's done with
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pad_alloc but this has many issues such as only being able to suggest 1 format
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and the need to allocate a buffer of this suggested format (some elements such
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as capsfilter only know about the format, not the size). We would ideally like
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to let upstream renegotiate a new format just like it did when it started.
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This could, for example, easily be triggered with a RENEGOTIATE event.
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- Remove the XML serialisation stuff.
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IMPLEMENTATION
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--------------
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- implement more QOS, see part-qos.txt.
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- implement BUFFERSIZE.
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- implement pad_block with probes? see above.
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DESIGN
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------
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- unlinking pads in the PAUSED state needs to make sure the stream thread is not
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executing code. Can this be done with a flush to unlock all downstream chain
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functions? Do we do this automatically or let the app handle this?
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