segment.position is meant for internal usage only, but the various
GST_EVENT_SEGMENT creationg/parsing functions won't clear that field.
Use the appropriate segment boundary as an initial value instead
When synchronizing the output by time, there are some use-cases (like
allowing gapless playback downstream) where we want the unlinked streams
to stay slightly behind the linked streams.
The "unlinked-cache-time" property allows the user to specify by how
much time the unlinked streams should wait before pushing again.
Multiqueue should only be used to cope with:
* decoupling upstream and dowstream threading (i.e. having separate threads
for elementary streams).
* Ensuring individual queues have enough space to cope with upstream interleave
(distance in stream time between co-located samples). This is to guarantee
that we have enough room in each individual queues to provide new data in
each, without being blocked.
* Limit the queue sizes to that interleave distance (and an extra minimal
buffering size). This is to ensure we don't consume too much memory.
Based on that, multiqueue now continuously calculates the input interleave
(per incoming streaming thread). Based on that, it calculates a target
interleave (currently 1.5 x real_interleave + 250ms padding).
If the target interleave is greater than the current max_size.time, it will
update it accordingly (to allow enough margin to not block).
If the target interleave goes down by more than 50%, we re-adjust it once
we know we have gone past a safe distance (2 x current max_size.time).
This mode can only be used for incoming streams that are guaranteed to be
properly timestamped.
Furthermore, we ignore sparse streams when calculating interleave and maximum
size of queues.
For the simplest of use-cases (single stream), multiqueue acts as a single
queue with a time limit of 250ms.
If there are multiple inputs, but each come from a different streaming thread,
the maximum time limit will also end up being 250ms.
On regular files (more than one input stream from the same upstream streaming
thread), it can reduce the total memory used as much as 10x, ending up with
max_size.time around 500ms.
Due to the adaptive nature, it can also cope with changing interleave (which
can happen commonly on some files at startup/pre-roll time)
This will mean a much lower delay before a subtitles track changes take
effect. Also avoids excessive memory usage in many cases.
This will also consider sparse streams as (individually) never full, so
as to avoid blocking all playback due to one sparse stream.
https://bugzilla.gnome.org/show_bug.cgi?id=600648
* Avoid the computation completely if we know we don't need it (not in
sync time mode)
* Make sure we don't override highest time with GST_CLOCK_TIME_NONE on
unlinked pads
* Ensure the high_time gets properly updated if all pads are not linked
* Fix the comparision in the loop whether the target high time is the same
as the current time
* Split wake_up_next_non_linked method to avoid useless calculation
https://bugzilla.gnome.org/show_bug.cgi?id=757353
In order to accurately determine the amount (in time) of data
travelling in queues, we should use an increasing value.
If buffers are encoded and potentially reordered, we should be
using their DTS (increasing) and not PTS (reordered)
https://bugzilla.gnome.org/show_bug.cgi?id=756507
Previously this code was just blindly setting the cached flow return
of downstream to GST_FLOW_OK when we get a SEGMENT.
The problem is that this can not be done blindly. If downstream was
not linked, the corresponding sinqlequeue source pad thread might be
waiting for the next ID to be woken up upon.
By blindly setting the cached return value to GST_FLOW_OK, and if that
stream was the only one that was NOT_LINKED, then the next time we
check (from any other thread) to see if we need to wake up a source pad
thread ... we won't even try, because none of the cached flow return
are equal to GST_FLOW_NOT_LINKED.
This would result in that thread never being woken up
https://bugzilla.gnome.org/show_bug.cgi?id=756645
There is no reason I can see to set mq->buffering = TRUE when
use_buffering is set; the code here also calls update_buffering(), which
will set mq->buffering = TRUE if this is warranted because of low buffer
levels.
https://bugzilla.gnome.org/show_bug.cgi?id=745937
multiqueue's queues stored percent value is the percentage from 0
to 100 (max-size-*) and should be compared with the requested limit
(high_percentage) set by the user and not with 100% to check if
buffering should stop. Otherwise we are only stopping buffering when the
queue gets completely full.
If we are pushing a serialized query into a queue and the queue is
filled, we will end in a deadlock. We need to release the lock before
pushing and acquire it again afterward.
https://bugzilla.gnome.org/show_bug.cgi?id=737794
It might cause deadlocks to post messages while holding the multiqueue
lock. To avoid this a new boolean flag is set whenever a new buffering percent
is found. The message is posted after the lock can be released.
To make sure the buffering messages are posted in the right order, messages
are posted holding another lock. This prevents 2 threads trying to post
messages at the same time.
https://bugzilla.gnome.org/show_bug.cgi?id=736295
Imagine the following 'pipeline'
--------------
p1/| 'fullqueue' |--- 'laggy' downstream
--------- / | |
-| demuxer | | multiqueue |
--------- \ | |
p2\| 'emptyqueue' |--- 'fast' downstream
--------------
In the case downstream of one single queue (fullqueue) has (a lot of) latency
(for example for reverse playback with video), we can end up having the other
SingleQueue (emptyqueue) emptied, before that fullqueue gets
unblocked. In the meantime, the demuxer tries to push on fullqueue, and
is blocking there.
In that case the current code will post a BUFFERING message on the bus when
emptyqueue gets emptied, that leads to the application setting the pipeline state to
PAUSED. So now we end up in a situation where 'laggy downstream' is
prerolled and will not unblock anymore because the pipeline is set to
PAUSED, the fullequeue does not have a chance to be emptied and
the emptyqueue can not get filled anymore so no more BUFERRING message
will be posted and the pipeline is stucked in PAUSED for the eternity.
Making sure that we do not try to "buffer" if one of the single queue
does not need buffering, prevents this situtation from happening though it lets the
oportunity for buffering in all other cases.
That implements a new logic where we need all singlequeue to need
buffering for the multiqueue to actually state buffering is needed,
taking the maximum buffering of the single queue as the reference point.
https://bugzilla.gnome.org/show_bug.cgi?id=734412
After EOS there will be no further buffer which could propagate the
error upstream, so nothing is going to post an error message and
the pipeline just idles around.
When the first segment has position != 0 and position > max-size-time
it will immediatelly cause the multiqueue to signal overrun.
This can happen easily with adaptive streams when switching bitrates
and starting a new group. The segment for this new group will have
a position that is much greater than 0 and will lead to this issue.
This is particularly harmful when the adaptive stream uses mpegts
that doesn't emit no-more-pads and it might happen that only one
of the stream pads was added when the multiqueue overruns and gets
the group ready for exposing. So the user will only get audio or
video.
The solution is to fallback to the sink segment while the source pad
has no segment.
https://bugzilla.gnome.org/show_bug.cgi?id=729124
They are very confusing for people, and more often than not
also just not very accurate. Seeing 'last reviewed: 2005' in
your docs is not very confidence-inspiring. Let's just remove
those comments.
Use the last result as a default when pushing a item from a single queue,
otherwise the status gets reset to _OK when pushing events.
This causes problems when mistakenly activating a not-linked stream
that is being ignored upstream as it is not being used (adaptive
scenarios), it will make the multiqueue post a buffering message
on a pad that won't receive buffers
https://bugzilla.gnome.org/show_bug.cgi?id=725917
When the single queue size was just bumped by 1 to allow more buffers to
be added, the buffers limit could be reduced to the current level when
setting the max-size-buffers property. This would result in a stall
since the queue would not grow anymore at this point.
Prevent this by not reducing a single queue size below the current
number of buffers + 1.
https://bugzilla.gnome.org/show_bug.cgi?id=712597
In the case where one singlequeue is full and all other are not linked, the
growing of the full queue does not work correctly. The result depends on if
the full queue is last in the queue list or not.
https://bugzilla.gnome.org/show_bug.cgi?id=722891
When prerolling/buffering, multiqueue has its buffers limit set
to 0, this means it can take an infinite amount of buffers.
When prerolling/buffering finishes, its limit is set back to 5, but
only if the current level is lower than 5. It should (almost) never be
and this will cause prerolling/buffering to need to wait to reach the
hard bytes and time limits, which are much higher.
This can lead to a very long startup time. This patch fixes this
by setting the single queues to the max(current, new_value) instead
of simply ignoring the new value and letting it as infinite(0)
https://bugzilla.gnome.org/show_bug.cgi?id=712597
This makes buffering stop in case a stream switch happens. This is
important for adaptive streams that can disable not-linked streams
to avoid consuming the network bandwidth.
https://bugzilla.gnome.org/show_bug.cgi?id=719575
After patch bda406c4, the state of the singlequeue was set to OK, but nothing
would then wake up the thread, as the other wakeup functions only look at
singlequeues that are marked as having received as not-linked.
https://bugzilla.gnome.org/show_bug.cgi?id=708200
If the multiqueue has automatically grown chances are good that
we will cause the pipeline to starve if the maximum level is reduced
below that automatically grown size.
https://bugzilla.gnome.org/show_bug.cgi?id=707156
We must be certain that we don't cause a deadlock when blocking the serialized
queries. One such deadlock can happen when we are buffering and downstream is
blocked in preroll and a serialized query arrives. Downstream will not unblock
(and allow our query to execute) until we complete buffering and buffering will
not complete until we can answer the query..
https://bugzilla.gnome.org/show_bug.cgi?id=702840
