bruce108
Head-Fier
- Joined
- Sep 19, 2006
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Right, voltage v current.
[size=medium]Hi Kingwa,[/size]
[size=medium]reading about usb audio standard I think I know now where lies a problem with firmware #4.[/size]
[size=medium]Here for example is not too technical explanation about usb audio:[/size]
[size=medium] http://www.edn.com/design/consumer/4376143/Fundamentals-of-USB-Audio?page=2[/size]
[size=medium]and you can read that feedback format should be 16.16.[/size]
[size=medium]This lead me to usb 2.0 specification and in point 5.12.4.2 you have:[/size]
[size=medium]“For high-speed endpoints, the value shall be encoded in an unsigned 12.13 format which fits into four bytes.[/size]
[size=medium] The value shall be aligned into these four bytes so that the binary point is located between the second and[/size]
[size=medium] the third byte so that it has a 16.16 format.”[/size]
[size=medium]Firmware #4 uses 14.18 feedback format. This must lead to incorrect calculation of momentary frequency,[/size]
[size=medium]when to send next portion of data. This is why Linux try to send 44.1kHz audio stream with frequency of 48kHz.[/size]
[size=medium]And this must cause buffer overflow in DAC.[/size]
[size=medium]Can someone check firmware #4 under Mac OS? Mac should expect standard 16.16 format too. [/size]
[size=medium]Kingwa could you prepare firmware #5 with standard implementation of usb audio with 16.16 feedback format?[/size]
[size=medium]Then we will be able to test it.[/size]
I was wondering if anyone has had any success using an android device to feed USB audio to this thing. I was thinking about switching to an android device as my primary source. If anyone has a Galaxy SIII or a note II, as well as a USB OTG cable they can test this out.
Hi Jlav,
I've got a Samsung Note 2 and the Compass 2 from Audio-GD. Need to grab a OTG cable somewhere and will test it one of these days. Will report back results when available.
Steve
Hi Jlav,
I've got a Samsung Note 2 and the Compass 2 from Audio-GD. Need to grab a OTG cable somewhere and will test it one of these days. Will report back results when available.
Steve
Thanks for the info. Did you use an OTG cable?