Hi Terry, Any time the audio subsystem can't feed JACK all the data it requires you get an XRUN error and the box goes red. All this means is if JACK expects 10 pieces of audio data to fill every second then at some point it only got 9, or 5 or if its really bad 1 or 0. The side effect to this is if there isn't enough audio to fill the time you get no audio and hear a glitch.
Obviously JACK asks for more than 10 pieces of audio a second. This is all controlled in your JACK settings under Frames/Period (default 1024), Sample Rate and Periods/Buffer (default 4 I think). From my basic understanding Frames/Period means 1024 pieces of audio per time period (I'm not sure how big this period is). Following on from that Periods/Buffer is how big the buffer will be to deal with glitches. Again I'm not sure if this means 4 periods out of 1024 are the buffer or its 4 * 1024 as a buffer (I'd imagine 4 * judging by the latency increases). Changing these settings increases or decreases the latency (bottom right) which is the delay between you pressing a button and audio coming out. In theory the bigger the delay the more resilience you have if your system gets bogged down before you get a VRUN. Anyway thats the JACK and red box thing. Theres plenty more on Google about JACK and tweaking settings. Just have a poke around. As for ALSA and Pulse, its kind of a stacked system. ALSA sits on top of your sound card and deals with anything coming in. As far as I understand the limitation of ALSA is that only one application can access it at a time (so no mixing audio from different sources). So you can get around this by using other programs to act as the mixers to ALSA. Pulse is relatively recent to Linux, it works as a mixer but there are no guarantees for low latency high quality sound. Unfortunately a lot of normal applications such as firefox and other random desktop things rely on Pulse for sound and to complicate things Rivendell can only work either directly with ALSA (which is actually the best setup for a studio broadcast that will do nothing else) or with JACK. I'll repeat that last bit, if you only need a broadcast machine to play Rivendell, you can uninstall pulse and give Rivendell sole access to the sound card. It will be more reliable by virtue of not stacking things together. If you need to mix sound for example on an editing machine or you broadcast with youtube videos or some strange concoction then you need to get Rivendell to work with JACK and then pulse to plug into that. So what you're achieving is ALSA --> JACK which splits off to --> Riv && Pulse --> Any other Audio apps. My eventual setup is to have Riv + ALSA only on the broadcast machines with the Riv, JACK, Pulse setup on general workstation editing machines. I live by keeping the broadcast simple as it tends to mean less 3am phone calls. On the editing machines I can tweak the latencies to make VRUNs rare (hopefully non-existent) but at the same time I can live with occasional glitches too so its not a problem for me. Any further JACK and ALSA things are probably much better explained by people with much more experience than me via Google. Either way hope this helps a bit, Wayne On Thu, 13 Oct 2011 01:51:34 +0100, Terry LeTourneau <[email protected]> wrote: > This is a follow-up question from yesterday (Thanks Wayne for all of your > help!) > > When you get a chance could anyone please assist me in understanding > JACK, > Pulse Audio and ALSA? As of right now, we have audio coming through the > board with JACK and Pulse Audio working together. The problem is I > think we > might have some confusion with our sound card (Delat44 - ICE1712) and > those > 2 programs. When we boot the system the JACK icon shows "green" but > after > about 10 minutes it will be inside a red box. Audio still works but it's > driving me nuts why. Is there another option here? Should we just run > Pulse Audio and ALSA? We're running RD 2.02 with Ubuntu 11.04. > > Thanks in advance! > > -Terry ####################### Scanned by MailMarshal ####################### #################################################################################################################################################################################################################### Attention: The information contained in this message is confidential and intended for the addressee(s) only. If you have received this message in error or there are any problems, please notify the originator immediately. The unauthorised use, disclosure, copying or alteration of this message is strictly forbidden. Christian Vision or any of its subsidiaries will not be liable for direct, special, indirect or consequential damages arising from alteration of the contents of this message by a third party or as a result of any virus being passed on. 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