Bugzilla – Bug 218
Sound drop-outs when streaming FLAC files to Squeezebox
Last modified: 2009-09-08 09:16:37 UTC
Periodically, whilst playing FLAC files from SlimServer to the Squeezebox, there will be momentary drop-outs in sound of maybe a second or two. This was observed on my wireless Squeezebox, but has also been observed by others on Slim Discussion Forum when wired. This does not appear to be a problem with the wireless bandwidth being unable to supply data to the Squeezebox quick enough - with the display changed to show the buffer fullness, it appears as though the buffer is 100% full normally, but suddenly drops to 0% as the sound drops out. Shortly thereafter, the buffer refills and playing continutes. There also appears to be plenty of spare CPU capacity and disk bandwidth on the server during this period. This is backed up by others reporting this same effect with a wired connection. It is not a problem with the FLACs themselves - configuring the server to transcode to MP3s instead, they play fine. Additionally, when playing the FLACs several times the drop-outs will be in different places. This has been observed on SlimServer v5.1.1 and Squeezebox v8, with both a Windows XP and a Linux server (mine is Linux, but the problem has also been noted on Windows XP servers by others). I am reasonably network-savvy, so if there is anything that I could test that would prove helpful then just ask. Also, if there is any configuration information I have not supplied that may be relevant then let me know.
I wonder if you could grab a network trace for the couple of seconds when this happens...
I was trying to do just this yesterday afternoon for several hours. Oddly, everything seemed to be working fine during this period and I couldn't reproduce the problem. This is strange as it was happening consistently the other evening. There had been some discussion on 'discuss' about possible network bandwidth problems. I initially discounted this theory because I would see the buffer suddenly drop to zero when the drop-out occurred, rather than seeing some draining effect. However, I've noticed that this buffer behavious is also that which occurs at the end of the every track with FLACs, and so it is perhaps consistent with a stall in the network after all. I'll continue to try to reproduce the problem whilst capturing packets.
I have the same here and found out that while the music stops for 2 seconds the server load is 100% on flac.exe
Does this happen with all FLAC files, or with specific ones? If the flac binary is pegging the CPU, a strace (or similar) on it during that time would help.
For me, I believe the problem has now 'gone away' - I know how annoying that is when trying to diagnose something, however. I'm pretty certain that it wasn't a CPU usage problem with me (it was Erwin who reported the CPU going high), as I had been watching for that as I know my server isn't hugely powerful (~500MHz). I *think* the problem for me could have actually been on the wireless side - I've since changed my AP's channel and I had a wireless and microwave-equipped neighbour move away, which could have helped. I'm on 5.4.1 now and I only very occasionally see this problem (it's rare enough that it doesn't bother me any more), and it seems to be more related to the time of day and day of week than the music that's playing or the CPU load on the server, so I would suspect it's really all down to wireless performance rather than software/squeezebox issues. Other people may have a different experience, however, as they did comment that they saw similar effects on a wired configuration.
Figured I should add my experience with this bug. This is an excerpt from a post I made to the list a couple weeks ago. When playing music on my SB, I experience periodic pauses. They happen, at a guess, every 30 minutes or so. But that's just a guess. When they happen, the SB display freezes (if the song title is scrolling, it stops) and the music also freezes. A short time later (normally 1-4 seconds, but sometimes it will last closer to 10) the music and the display resume exactly where they left off. I play almost exclusively FLAC files. My SB is WIRED not wireless. There is typically very litle network activity on my network, so I don't expect network saturation is causing this. My SB is connected to the server via Microsoft wireless base station/4-port router. However, the connection between the SB and the server is entirely wired. There is a cable from the SB to the router/basestation, a cable from that to a switch upstairs, and a cable from that switch to my server. I have server version 5.4.0 running on Windows XP. My firmware level is 40. I have the graphical display. Nothing else runs on the server except the Slimserver software. I recently also installed Norton Antivirus, but I was experiencing this problem prior to the installation. I also recently moved to Windows SP2, but again, I was experiencing this problem prior to that. My system has 512MB RAM and 950MHz AMD Athlon processor. I have observed this in previous server/firmware levels as well. I don't recall when it first began showing up. I've also noticed that my music hitches if I am using the web interface to add music to the playlist, although it does not normally pause if I add music using the remote control. I also experience these hitches if I adjust the shuffle setting, whether via remote control or via the web interface.
Someone on the mailing list recently mentioned that he went to the Feb 10th 5.4.1 nightly build and this problem cleared up for him (based on 6 hours of observation). Accordingly, I've just moved to the 5.4.1 Feb 12th nightly, to see if it clears it up for me. I will report back after a couple days listening (or sooner, if I continue to observe it).
Even after the update to the latest 5.4.1 build, I continue to observe these dropouts. The frequency and duration of the dropouts does not appear to have changed.
This appears to be fixed for 6.0. Can you confirm?
I updated to 6.0 a few days ago. I have not listened to enough music since then to confirm that the periodic drop outs are gone, but hopefully over the weekend I will get the chance to do some extended listening. However, I still definitely observe drop-outs if I perform certain operations during music playback. For example, if I add a large playlist into the now playing list, this will cause the music to pause in playback for at least 5-10 seconds. Should I open a separate bug to track those dropouts?