First of all this is a really cool product. I am trying to work my way through some issues.

The one I am concerned with here is audio dropout. It appears to happen at random and can't be duplicated. I have monitored CPU usage and there is nothing to indicate the CPU is maxxed out or that memory is short. There is plenty of memory and I just watched it happen at 4% CPU. The files being played back are FLAC coming from a RAID 5 array connected to the host by Esata.

1) Is there a way to increase the playback buffer?

2) Can anyone suggest alternative solutions or troubleshooting?

did you also monitor i/o ? were there other processes heavily accessing i/o at those times - try the command iostat or ksysguard (a sheet (tab) can show usage for the system and/or a device by selecting a disk's throughput sensor?

does switching the phonon-backed (vlc vs gstreamer) alleviate the issue?

you can try adjusting the buffers in the VLC app's settings if you use the phon-backend-vlc and see if they are recognized and used

Erm, guys, this will not work, the phonon-backend-vlc uses the libvlc library, it doesn't use VLC as an application.

Mamarok wrote:Erm, guys, this will not work, the phonon-backend-vlc uses the libvlc library, it doesn't use VLC as an application.

didn't think so, but figured it was something to try - so there's no way to increase buffers?

Not that I know of. in any case, that should be asked the Phonon guys. I am moving this to Graphics&Multimedia, as it is not Amarok specific anyway.

edit vlc, find the vlc config (supposedly something like $HOME/.config/vlc/vlcrc) and copy it to $HOME/.config/Phonon/vlc.conf. phonon-vlc will now use the settings defined in the config unless the setting is explicitly set through phonon itself.

I am running windows 7.0. I had this problem with foobar and adjusting the buffer resolved the problem.

This may not be appropriate for graphics and multimedia forum and may well be Amarok. Here is why. I know beyond a doubt that the hardware is fine. It is windows 7 with 8GB memory and a fast quad core. Since it is my HTPC I have it stripped down to just support multimedia playback, no other applications. Foobar plays audio flawlessly. All the files are audio in flac format and I suspect that what is happening is that since Amarok is more feature rich the application may not be able to process all of the audio in real time and drops out. I did have a similar issue once on this machine with foobar so I adjusted playback buffer and have never seen the issue with foobar since. Note that the audio buffer is implemented by foobar directly and is not a feature of an audio back end. In fact it is really simple because I am outputting in SPDIF, there is not even ADC conversion taking place, that is all being done outboard. I have watched the DAC and when the dropout occurs there is no data. Amarok will be reading the flac files and decoding flac. I am not sure what flac library is used and how it is implemented. Any help or pointers here would be appreciated. I know if I could just adjust a playback buffer I am fine. It's not a feature of windows but is instead a feature that if implemented would have to be in Amarok.

This is still something which would need to be implemented on the Phonon backend level - as that is where all the audio/video decoding, etc. is handled.
In terms of the issue - how big are these FLAC files, and are they stored on local, fast storage or network based, slow storage?

The flac files are on a RAID 5 array and are track sized about 25 MB each. The RAID implementation is HW and I have checked IO, memory and CPU load. All are well within range. Foobar2000 plays the files flawlessly but it doesn't have the features that Amarok does. VLC also plays the files flawlessly, For some reason Amarok seems to have these subsecond dropouts (I would estimate in range of 500ms) which is more than enough to be be very bothersome, It occurs roughly every 2 or 3 tracks. When I look at the backend all is says is VLC. The version is 0.6.2 and there is nothing to configure. Note that this is all on windows. On Linux Amarok simply packed it in when trying to load the flac music library, which takes hours so I am not going down that road again as each trial is half a day. I am using SPDIF out so all the ADC is offboard and because this is a HTPC I have disabled all nonused HW - serial port, midi port, parallel port and all services unrelated to audio and video playback. My gut tells me that this is one of a flac decoder problem or an IO problem. The chain is pretty simply Hardware Raid->File Read->FLAC decode->SPDIF out

When the buffer becomes empty, is anything of relevance printed out on the terminal? Unfortunately I suspect you'll need modifications to the Phonon VLC backend in order to adjust the buffer sizes used.