[Voyage-linux] Glitches on Playback Start/Resume with Arcam rDAC and Voyage MPD 0.8

[John Mayer]

I had some free time today so I decided to test some more things:

When playing a high resolution (say 24bit/96kHz) PCM WAV file using "aplay -v -Dhw:0,0 highresfile.wav"
I can reproduce the same glitches on the very beginning of playback. Stdout doesn't show any errors and playback is
fine after the initial glitches.

When I use the Arcam rDAC with a MacBook Pro and e.g. Fidelia (with automatic sample rate switching enabled)
I get no such glitches, though it seems that Fidelia when in paused or stopped state is sending silence to the sound card
at a fixed resolution; I cannot confirm that technically however apart from my Marantz DAC acting as if there was input.

Thus it currently seems to me that the glitches have something to do with the way snd-usb-audio communicates with the
Arcam rDAC. I could get rid of the glitches if I could get MPD to play silence when paused or stoppedinstead of ending 

the stream to the sound card. Does anyone know how to make MPD do that? Or anyone other way to fix the described issue?



________________________________
 From: John Mayer <sik_lescinovid at yahoo.com>
To: "voyage-linux at list.voyage.hk" <voyage-linux at voyage.hk> 
Sent: Friday, January 20, 2012 12:05 AM
Subject: [Voyage-linux] Glitches on Playback Start/Resume with Arcam rDAC and Voyage MPD 0.8
 

Hi,

I'm having curious issues running Voyage MPD 0.8 on a Compaq Mini 110c-1100dx netbook connected to an Arcam rDAC via USB.
Whenever I resume playback of a FLAC file from a stopped or paused state there are loud glitches at the very beginning
of playback lasting for at most a second. They seem to be most frequent with high resolution files and most prominent with files that have
little to no silence at the beginning. Additionally my kernel log always shows a message of the type "2:1:1: cannot get freq at ep 0x1" when I
start or resume playback of any file. I have also tried playing music from an attached USB harddrive and from the internal one, the glitches were
present both times.

Finally I want to mention that once a file is playing it plays without any glitches whatsoever. Also when I have multiple files, of different bit/sample rate even,
in a playlist and I switch from one playing file to another there are no glitches. The glitches only seem to appear when the sound card is moved form an idle state
into a playing one.

Does anyone have any ideas what the reason for this might be, or at least a possible solution to getting rid of the glitches?
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