demuxing mp4 and queues

Wudo Balmus wudo.balmus at gmail.com
Tue Mar 5 22:40:53 UTC 2019


Sorry, it should be:

However, when there is a queue for h.264 decoder, but there is no 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

wt., 5 mar 2019 o 22:38 Wudo Balmus <wudo.balmus at gmail.com> napisał(a):

> 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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