MLP Report

Errata and Contingencies
Operating System
Failing Test
Expiry
Date
ID
Number
Type
Error Description
Windows 7
Windows 7 64-bit
Windows Vista
Windows Vista 64-bit
1) Class Driver
AC3 Test -
Win7 (System)
2) HDAudio
Class Driver
Test - Vista or
Server08
(System)
06/01/2010
1256
Erratum
The HD Audio class driver hdaudio.sys exposes AC-3 data
ranges on S/PDIF Kernel Streaming pins incorrectly.
The compressed AC-3 transport is "stereo", "16-bit", and at the
same sample rate as the uncompressed format. As such, AC-3
data ranges are expected to have MaximumChannels = 2, and
MinimumBitDepth = MaximumBitDepth = 16.
However, the HD Audio class driver sometimes incorrectly
exposes a MaximumBitDepth of 24 or even 32.
Windows Vista
Windows Vista 64-bit
HDAudio Class
Driver Test -
Vista or
Server08
(System)
01/31/2011
142
Erratum
HDMI is required to support 44.1 kHz on Windows 7 The
Windows Vista HD Audio class driver does not support 44.1 kHz
sample rates. There is an errata to cover this violation of
AUDIO-0023. It was mistakenly applied to third-party drivers. As
of Windows 7, the Windows Vista HD Audio class driver
supports 44.1 kHz sample rates on hardware that advertises
support for it. AUDIO-0023 is applicable. This is a filter to allow
vendors to ship with systems that violated AUDIO-0023 but
were incorrectly filtered by the Vista filter. Hardware that does
not support 44.1 needs to be updated to support 44.1, and
advertise that support in a way that the Microsoft HD Audio
class driver can pick up on. Third-party drivers need to relay this
support to the OS correctly.
Windows 7
Windows 7 64-bit
Window Vista
1) Class Driver
Fidelity Test -
Win7 (System,
Manual)
2) HDAudio
Class Driver
Fidelity Test-
Vista (System,
Manual)
3) Fidelity Test
(System,
Manual)
12/01/2010
1012
Erratum
Fidelity uses too small of a buffer and wakes up too
infrequently during the System Activity test. This causes errors
like: Noise level during system activity on (left or right) channel
73.2016 dB: *** FAIL *** (requirement >= 80 dB)
Windows 7
Windows 7 64-bit
Windows Vista
Windows Vista 64-bit
1) Class Driver
Fidelity Test -
Win7 (System,
Manual)
2) HDAudio
Class Driver
Fidelity Test-
Vista (System,
Manual)
07/31/2011
598
Erratum
The European Union requires the headphone output level to be
<= 150 mVrms for headphone jacks. There's a note in WLP
requirement AUDIO-0006 that states, in the presence of
regional regulations, the output level requirement for
headphones is dropped from >= 1000 mVrms to >= 120 mVrms.
This provides freedom for manufacturers to meet both the EU
<= 150 mVrms @ 32 Ohms and the WLP >= 120 mVrms @ 32
Ohms requirements. The Fidelity Test tests headphones at 300
Ohm load, though. Without knowledge of the output impedance
at the jack, the test cannot extrapolate what the output level at
32 Ohms would have been from the output level at 300 Ohms.
The test assumes that the output level at 32 Ohms will be
*less* than the output level at 300 Ohms, though. So any
measurement >= 120 mVrms at 300 Ohms "could be" a passing
result, depending on the output impedance.