usb/183409: USB Class 2 audio device playback issue

[Taner]

>Number:         183409
>Category:       usb
>Synopsis:       USB Class 2 audio device playback issue
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-usb
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Oct 28 16:20:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Taner
>Release:        10.0-BETA1
>Organization:
>Environment:
FreeBSD bsd 10.0-BETA1 FreeBSD 10.0-BETA1 #2 r256773M: Sun Oct 20 20:52:31 EEST 2013     root at bsd:/usr/obj/usr/src/sys/GENERIC  amd64
>Description:
My asyncronous USB to I2S interface (http://amanero.com/) has detected on a amd64 FreeBSD-10.0-BETA1 system. But playback is crackling like old vinyl records.

I haven't similar issues with other operating systems.

With enabling debug, lots of these error messages appear on dmesg output:

uaudio_chan_play_sync_callback: Value = 0x0005fff8
uaudio_chan_play_sync_callback: Comparing 47998 < 48000
uaudio_chan_play_sync_callback: Value = 0x0005fff6
uaudio_chan_play_sync_callback: Comparing 47998 < 48000

or

uaudio_chan_play_sync_callback: Value = 0x000bfff0
uaudio_chan_play_sync_callback: Comparing 95997 < 96000
uaudio_chan_play_sync_callback: Value = 0x000bfff0
uaudio_chan_play_sync_callback: Comparing 95997 < 96000

---> dmesg output while device attached

uaudio0: at uhub1, port 3, addr 1 (disconnected)
pcm0: detached
uaudio0: <Amanero Technologies Combo384 Amanero, class 239/2, rev
2.00/1.80, addr 1> on usbus0
uaudio0: Play: 96000 Hz, 2 ch, 32-bit S-LE PCM format, 2x8ms buffer.
uaudio0: Play: 88200 Hz, 2 ch, 32-bit S-LE PCM format, 2x8ms buffer.
uaudio0: Play: 48000 Hz, 2 ch, 32-bit S-LE PCM format, 2x8ms buffer.
uaudio0: Play: 44100 Hz, 2 ch, 32-bit S-LE PCM format, 2x8ms buffer.
uaudio0: Play: 32000 Hz, 2 ch, 32-bit S-LE PCM format, 2x8ms buffer.
uaudio0: No recording.
uaudio0: No MIDI sequencer.
pcm0: <USB audio> on uaudio0
uaudio0: No HID volume keys found.
>How-To-Repeat:
Playback any audio file/stream.
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: