Gstreamer audio mixer issue

[jim nualart]

I faced similar issues a while back. A search in the group for something
like "audiomixer gaps" should pull up the related posts.

If memory serves, I found that using "adder" instead of "audiomixer"
eliminated the gaps. As did setting a non-zero latency in the audiomixer
properties. However, in my case, the latency value only seemed to have any
effect at all if I also placed a queue after the audiomixer.



>
> Message: 1
> Date: Tue, 5 Jan 2021 09:37:25 -0500
> From: Guillaume Cartier <gucartier at gmail.com>
> To: Discussion of the development of and with GStreamer
>         <gstreamer-devel at lists.freedesktop.org>
> Subject: Re: Gstreamer audio mixer issue
> Message-ID:
>         <CAN4e_LmOgJ6_q4yQOSaaL2jD_LZi80hjM=PJR1rC=
> 4qeGFabqQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi dananjaya, we are also using GStreamer for a project that involves
> mixing multiple live sources together.
>
> For us, the audiomixer would very often generate what we called "gritches"
> that upon looking at the output in Audacity were revealed to be small
> silence gaps in the output. Reading the source code and playing with it has
> led to the gst_aggregator_pad_has_space function that has a test that I
> believe is incorrect (in all humbleness being fairly new to GStreamer) :
>
> if (self->priv->latency == 0)
>   return FALSE;
>
> I think this test should only apply in the non-live case, but in any case
> the good news is that by setting latency to any value in our audiomixer
> element (even 1), this has solved most of our problems.
>
> PS: You could also replace audiomixer with liveadder which is a subclass of
> audiomixer that by default sets latency to 30ms.
>
> On Tue, Jan 5, 2021 at 6:51 AM dananjaya <pulzappcheck890 at gmail.com>
> wrote:
>
> > Hi,
> > I am trying the below pipeline to capture 2 1080p usb video streams while
> > previewing, with 2 usb audio sources mixed together.
> >
> > The issue is, the audio mixed and captured is containing lots of
> artifacts
> > such as click sounds. How can I resolve this issue.
> >
> > gst-launch-1.0 -e mp4mux name=mux ! filesink location=feed1mp1080HS.mp4
> > v4l2src device=/dev/video1 ! tee name=t1 t1. ! queue ! video/x-raw,
> > width=1920, height=1080, framerate=30/1 ! nvvidconv ! queue !
> nvv4l2h264enc
> > maxperf-enable=1 bitrate=4000000 profile=4 ! queue ! h264parse ! queue !
> > mux.video_0 audiomixer name=mixer ! audioconvert ! voaacenc ! aacparse !
> > mux.audio_0 pulsesrc
> > device="alsa_input.usb-VXIS_Inc_ezcap_U3_capture-02.analog-stereo" !
> queue
> > !
> > audio/x-raw,width=16,depth=16,rate=44100,channel=1 ! queue ! mixer.sink_0
> > pulsesrc
> >
> >
> device="alsa_input.usb-C-Media_Electronics_Inc._USB_Advanced_Audio_Device-00.analog-stereo"
> > ! queue ! audio/x-raw,width=16,depth=16,rate=44100,channel=1 ! queue !
> > mixer.sink_1 t1. ! queue ! video/x-raw, width=1920, height=1080,
> > framerate=30/1 !  nvvidconv ! queue !
> >
> "video/x-raw(memory:NVMM),width=959,height=540,framerate=30/1,format=NV12"
> > !
> > queue ! nvoverlaysink overlay-x=0 overlay-y=270 overlay-w=959
> overlay-h=540
> > overlay=1 v4l2src device=/dev/video2 ! tee name=t2 t2. ! queue !
> > video/x-raw, width=1920, height=1080, framerate=30/1 ! nvvidconv ! queue
> !
> > nvv4l2h264enc maxperf-enable=1 bitrate=4000000 profile=4 ! queue !
> > h264parse
> > ! queue ! mp4mux ! filesink location=feed2mp1080HS.mp4 t2. ! queue !
> > video/x-raw, width=1920, height=1080, framerate=30/1 ! nvvidconv ! queue
> !
> >
> "video/x-raw(memory:NVMM),width=960,height=540,framerate=30/1,format=NV12"
> > !
> > queue ! nvoverlaysink overlay-x=960 overlay-y=270 overlay-w=960
> > overlay-h=540 overlay=2
> >
> > Thanks in advance
> >
> >
> >
>
>
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