<div dir="ltr">Hi, On a CentOS 7 instance (3.10.0-1062.18.1.el7.x86_64), I'm using Snowmix video mixer (<a href="https://snowmix.sourceforge.io/">https://snowmix.sourceforge.io/</a>) version 0.5.1 with its output attached to the following pipeline (GStreamer 1.16.2, compiled from source): outsocket=/tmp/53cc8523-dd33-47ac-8cd6-c69f42315578prog width=320 height=180 VIDEOFORMAT="video/x-raw,framerate=25/1,width=$width,height=$height,format=BGRA,pixel-aspect-ratio=1/1" AUDIOFORMAT="audio/x-raw,format=S16LE,layout=interleaved,rate=48000,channels=2" ( echo "audio sink ctr isaudio 1" ; sleep 1000000) | nc 127.0.0.1 $SNOWMIX_PORT | \ ( head -1 /usr/local/bin/gst-launch-1.0 -v rtpbin name=bin \ shmsrc socket-path=$outsocket do-timestamp=true is-live=true ! \ $VIDEOFORMAT ! \ queue ! \ videoscale ! \ videoconvert ! \ x264enc bitrate=488 key-int-max=25 aud=false ! \ video/x-h264,profile=baseline ! \ rtph264pay config-interval=0 pt=96 ! \ bin.send_rtp_sink_0 bin.send_rtp_src_0 ! \ udpsink host=224.0.0.0 port=7000 sync=true \ fdsrc fd=0 do-timestamp=true ! \ $AUDIOFORMAT ! \ queue max-size-buffers=200 max-size-time=1000000000 max-size-bytes=192000 ! \ identity silent=false ! \ audiorate tolerance=40000000 skip-to-first=false ! \ audioresample ! \ audioconvert ! \ queue ! \ opusenc bitrate=120000 ! \ rtpopuspay pt=97 ! \ bin.send_rtp_sink_1 bin.send_rtp_src_1 ! \ udpsink host=224.0.0.0 port=7002 sync=true ) & I start snowmix and then the gst-launch pipeline. Sometimes (about half of the times I start the pipeline) snowmix gives the following error message: Frame xxx - audio sink 1 would block" This behaviour was reported to Snowmix (you can find more details and logs there): <a href="https://sourceforge.net/p/snowmix/discussion/Snowmix_Support_Forum/thread/ccee999022/">https://sourceforge.net/p/snowmix/discussion/Snowmix_Support_Forum/thread/ccee999022/</a> Checking the logs from gst-launch, I've seen the following. If at the beginning I get a line with a high dts (not always exactly the same high value), after some seconds (usually less than a minute) I will get a would block error on Snowmix: /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (3496 bytes, dts: none, pts: none, duration: none, offset: 387980, offset_end: -1, flags: 00000000 , meta: none) 0x7fd69c02bb40 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (4096 bytes, dts: none, pts: none, duration: none, offset: 391476, offset_end: -1, flags: 00000000 , meta: none) 0x7fd69c02bc60 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (3616 bytes, dts: none, pts: none, duration: none, offset: 395572, offset_end: -1, flags: 00000000 , meta: none) 0x7fd69c02bd80 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (4096 bytes, dts: 9:30:20.594089255, pts: 9:30:20.594089255, duration: none, offset: 399188, offset_end: -1, flags: 00000000 , meta: none) 0x7fd69c02bea0 0:00:03.744090862 [332m13087 [00m 0x16f71e0 [36mINFO [00m [00;01;34m GST_EVENT gstevent.c:820:gst_event_new_caps: [00m creating caps event video/x-h264, codec_data=(buffer)0142c00dffe1001d6742c00dd901419f9f016a0c020b4a000003000200000300651e28549001000468cb8cb2, stream-format=(string)avc, alignment=(string)au, level=(string)1.3, profile=(string)baseline, width=(int)320, height=(int)180, pixel-aspect-ratio=(fraction)1/1, framerate=(fraction)25/1, interlace-mode=(string)progressive, colorimetry=(string)bt601, chroma-site=(string)jpeg However, if dts values start at zero, I will not get a would block error on Snowmix: /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (3552 bytes, dts: none, pts: none, duration: none, offset: 372480, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c01f6c0 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (4096 bytes, dts: none, pts: none, duration: none, offset: 376032, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c01f7e0 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (3764 bytes, dts: none, pts: none, duration: none, offset: 380128, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c01f900 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (4096 bytes, dts: 0:00:00.023109823, pts: 0:00:00.023109823, duration: none, offset: 383892, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c01fa20 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (3416 bytes, dts: 0:00:00.023165513, pts: 0:00:00.023165513, duration: none, offset: 387988, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c01fb40 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (4096 bytes, dts: 0:00:00.063396237, pts: 0:00:00.063396237, duration: none, offset: 391404, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c01fc60 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (3596 bytes, dts: 0:00:00.063551013, pts: 0:00:00.063551013, duration: none, offset: 395500, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c01fd80 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (4096 bytes, dts: 0:00:00.105300171, pts: 0:00:00.105300171, duration: none, offset: 399096, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c03f480 /GstPipeline:pipeline0/GstIdentity:identity0: last-message = chain ******* (identity0:sink) (3764 bytes, dts: 0:00:00.105402911, pts: 0:00:00.105402911, duration: none, offset: 403192, offset_end: -1, flags: 00000000 , meta: none) 0x7f990c03f360 What could be causing these wrong (9:30:20.594089255) dts values? Francesc -- <div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Francesc Pinyol Margalef <a href="http://www.francescpinyol.cat/" target="_blank">http://www.francescpinyol.cat/</a></div></div></div>