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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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f03c9fb1e7
Original commit message from CVS: Added a simple mp3 mixer pipeline setup with an explanation of how EOS could be handled with it.
227 lines
8.5 KiB
Plaintext
227 lines
8.5 KiB
Plaintext
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case 1)
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(--------------------------------------------------)
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! bin !
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! (--------) (--------) (--------) !
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! ! fakesrc! !identity! !fakesink! !
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! ! src ----- sink src ---- sink ! !
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! (--------) (--------) (--------) !
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(--------------------------------------------------)
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.scheduling.
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case1 has just one scheduled entity (chain) no problem here.
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.eos.
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fakesrc detects the end of stream. It just returned the last buffer.
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The next _pull will cause the srcpad to trigger gst_pad_set_eos ().
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After that it will return a NULL buffer.
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gst_pad_set_eos() will notify the parent about the plugins attempt to
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signal eos. the parent disables scheduling for the chain containing
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fakesrc.
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no more chains are being scheduled so the bin fires EOS.
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case 2)
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(-----------------------------------------------------------------------)
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! bin !
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! (---------------) !
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! !thread ! !
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! (--------) (--------) (--------) ! (--------)! !
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! ! fakesrc! !identity! ! queue ! ! !fakesink!! !
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! ! src ----- sink src ---- sink src ---- sink !! !
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! (--------) (--------) (--------) ! (--------)! !
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! (---------------) !
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(-----------------------------------------------------------------------)
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.scheduling.
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case2 has two scheduled entities: fsr-i-q, q-fsk.
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The first one is scheduled by the bin, the second one by the thread.
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.eos.
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fakesrc detects the end of stream. It just returned the last buffer.
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The next _pull will cause the srcpad to trigger gst_pad_set_eos ().
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After that it will return a NULL buffer.
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gst_pad_set_eos() will notify the parent about the plugins attempt to
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signal eos. the parent will take chain1 out if its scheduled chains.
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the bin does not fire EOS yet because the thread has not yet signaled
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EOS.
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after the queue has sent out the last buffer, its calls eos on its
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src pad. the chain with the queue is removed from the threads scheduled
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chains. there are no more chains to schedule, the thread fires EOS.
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The bin now has no more scheduled chains and no more pending subbins,
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it fires EOS.
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case 3)
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(-----------------------------------------------------------------------)
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! bin !
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! (---------------) !
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! !thread ! !
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! (--------) (--------) (--------) ! (--------)! !
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! ! fakesrc! ! tee ! ! queue1 ! ! !fakesink!! !
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! ! src ----- sink src ---- sink src ---- sink !! !
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! (--------) ! ! (--------) ! (--------)! !
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! ! ! (---------------) !
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! ! ! !
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! ! ! (---------------) !
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! ! ! !thread ! !
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! ! ! (--------) ! (--------)! !
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! ! ! ! queue2 ! ! !fakesink!! !
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! ! src ---- sink src ---- sink !! !
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! ! ! (--------) ! (--------)! !
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! (--------) (---------------) !
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(-----------------------------------------------------------------------)
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.scheduling.
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case3 has tree scheduled entities: fsr-t(-q1,-q2), q1-fsk. q2-fsk
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the first one is managed by the bin, the second two are managed by the
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threads.
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.eos.
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fakesrc detects the end of stream. It just returned the last buffer.
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The next _pull will cause the srcpad to trigger gst_pad_set_eos ().
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After that it will return a NULL buffer.
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chain1 is taken out of the scheduling algorithm of the bin.
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after a while, the threads finish their scheduling and fire EOS too.
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The bin now has no more scheduled chains and no more pending subbins,
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it fires EOS.
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case 4)
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(-----------------------------------------------------------------------)
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! bin !
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! (---------------) !
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! !thread ! !
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! (--------) (----------) (--------) ! (--------)! !
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! ! fakesrc! !mpeg1parse! ! queue1 ! ! !fakesink!! !
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! ! src -- sink src ---- sink src ---- sink !! !
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! (--------) ! ! (--------) ! (--------)! !
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! ! ! (---------------) !
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! ! ! !
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! ! ! (---------------) !
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! ! ! !thread ! !
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! ! ! (--------) ! (--------)! !
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! ! ! ! queue2 ! ! !fakesink!! !
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! ! src ---- sink src ---- sink !! !
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! ! ! (--------) ! (--------)! !
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! (----------) (---------------) !
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(-----------------------------------------------------------------------)
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this case differs from case3 in that one of the queues can be empty
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while the other isn't. we assume queue1 is empty while queue2 isn't yet.
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.scheduling.
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case3 has tree scheduled entities: fsr-t(-q1,-q2), q1-fsk. q2-fsk
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the first one is managed by the bin, the second two are managed by the
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threads.
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.eos.
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fakesrc detects the end of stream. It just returned the last buffer.
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The next _pull will cause the srcpad to trigger gst_pad_set_eos ().
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After that it will return a NULL buffer.
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chain1 is taken out of the scheduling algorithm of the bin.
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after a while, the threads finish their scheduling and fire EOS too.
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chain2 (with queue1) is taken out of the scheduling first because it
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is empty.
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chain3 (with queue2) finally removes its last scheduled chain and
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fires EOS.
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The bin now has no more scheduled chains and no more pending subbins,
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it fires EOS.
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case 5)
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(-----------------------------------------------------------------------)
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! bin !
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! (---------------) !
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! !audiosink ! !
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! (--------) (----------) (--------) ! ! !
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! !disksrc1! ! effect ! ! mixer ! ! ! !
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! ! src -- sink src ---- sink src -- sink ! !
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! (--------) (----------) ! ! ! ! !
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! ! ! (---------------) !
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! (--------) (----------) ! ! !
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! !disksrc2! ! effect ! ! ! !
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! ! src -- sink src ---- sink ! !
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! (--------) (----------) (--------) !
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(-----------------------------------------------------------------------)
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This is a simple audio mixer (mp3audio mixer).
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We assume disksrc1 is going to be in EOS while disksrc2 is still in !EOS
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.scheduling.
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two chains are detected: disksrc1-effect-mixer-audiosink,
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disksrc2-effect-mixer-audiosink
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.eos.
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disksrc1 has passed the last buffer in the _get function. with its next
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call to _get, it will return a NULL buffer and set the src pad to EOS.
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the EOS call travels up till the mixer element because it has overridden
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the handler. The first chain is disabled from the scheduler.
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finally disksrc2 run into EOS, same procedure as with disksrc1, except
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now the mixer also sets EOS to its src pad, chain2 becomes inactive too
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and the bin fires EOS because there are no more chains to schedule.
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somebody sets the location of disksrc1 to a new mp3 file, the srcpad
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is set to !EOS, chain1 is scheduled again, mixer is activated again too
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and audio is playing again...
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