demuxing mp4 and queues

[Wudo Balmus]

Just noticed that the version without a queue for h.264 decoder, but with a
queue for aac decoder works too:

gst-launch-1.0 -v filesrc location=working.mp4 ! qtdemux name=a a. !
avdec_h264 ! videoconvert ! autovideosink a. ! queue ! avdec_aac !
autoaudiosink

However, when there is no queue for h.264 decoder, but there is a queue for
aac decoder, it hangs:

gst-launch-1.0 -v filesrc location=working.mp4 ! qtdemux name=a a. ! queue
! avdec_h264 ! videoconvert ! autovideosink a. !  avdec_aac ! autoaudiosink

So the question is, why aac decoder needs a queue?

Best regards,
Wudo

wt., 5 mar 2019 o 22:11 Wudo Balmus <wudo.balmus at gmail.com> napisał(a):

> Hello,
> I'm trying to demux and playback an mp4 file with h.264 video and aac
> audio. This pipeline works fine:
>
> gst-launch-1.0 -v filesrc location=working.mp4 ! qtdemux name=a a. ! queue
> ! avdec_h264 ! videoconvert ! autovideosink a. ! queue ! avdec_aac !
> autoaudiosink
>
> However when the queues are removed, it hangs, nothing is played back:
>
> gst-launch-1.0 -v filesrc location=working.mp4 ! qtdemux name=a a. !
> avdec_h264 ! videoconvert ! autovideosink a. ! avdec_aac ! autoaudiosink
>
> It works fine without a queue when I just try to playback video without
> audio:
>
> gst-launch-1.0 -v filesrc location=working.mp4 ! qtdemux name=a a. !
> avdec_h264 ! videoconvert ! autovideosink
>
> I'm trying to understand why queues are necessary in this scenario. Cannot
> qtdemux just write data to video/audio decoder without the queues?
>
> Best regards,
> Wudo
>
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