I don't know how to put this, an Apple Audio HW bug? Post: 302907224

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Operating Systems OS X (Apple) I don't know how to put this, an Apple Audio HW bug? Post 302907224 by wisecracker on Thursday 26th of June 2014 03:40:32 PM

06-26-2014

Registered User

I don't know how to put this, an Apple Audio HW bug?

Hi guys and gals...

Apologies for any typos...

Well I have a major problem and I don't know how to take it further so I need your advice AND help...
Found from the AudioScope.sh calibration method(s)...

I think I have found a HW bug in Apple gear...

This has been checked so far on a new iPhone 5S,
a 3 month old iPad Air and my Macbook Pro...

As a confirmation I have tried it on my old Blackberry Phone, Windows Vista and XP on various machines
Debian Linux and PCLinuxOS 2009 on an HP laptop and an Acer Aspire One netbook these work perfectly as
the sound _card_ should...
It has even been checked as a RAW file in /dev/dsp too and is correct.
(Will check CygWin tomorrow.)

Consider the code below:-
It was written to set up the vertical amplifier polarity and works as designed BUT........

Code:

#!/bin/bash --posix
> /tmp/pulse.wav
printf "\x52\x49\x46\x46\x24\x00\x01\x00\x57\x41\x56\x45\x66\x6d\x74\x20\x10\x00\x00\x00\x01\x00\x01\x00\x40\x1f\x00\x00\x40\x1f\x00\x00\x01\x00\x08\x00\x64\x61\x74\x61\x00\x00\x01\x00" >> /tmp/pulse.wav
for n in {0..8191}
do
	printf "\xFF\xFF\x00\x00\x00\x00\x00\x00" >> /tmp/pulse.wav
done
afplay /tmp/pulse.wav
exit 0

This works perfectly on the RANDOM gear as it should; a NEGATIVE going pulse NOT a POSITIVE one.
When pulse.wav is transferred to run on the Apple gear above the waveform is inverted, I.E. it is a
POSITIVE going pilse. AFAIK this is wrong.

What I would dearly like is for the interested on here to check the waveform from the earphone socket
against a known Oscilloscope and reply to this thread.

You can test on anything that plays a .WAV file. The quality of the wave is NOT important the polarity
IS however...

It should look something like this:-

Code:

 =-+  +-----------+  +-------  <- 0x00 Unsigned 8 bit.
   |  |           |  |
   |  |           |  |
   |  |           |  |
   |  |           |  |
   +--+           +--+  <- 0xFF Unsigned 8 bit.

Remember quality is NOT important, polarity IS...

I will be checking on other machines and phones myself over the WE...

Many thanks in advance...

NOTE:- I have not yet posted anywhere else and hope I am wrong. thanks guys and gals...

If this is consitent throughout Apple gear then I don't know how to take it further...

Barry.

EDIT:
Many thanks to my workmate Richard Carter for letting me test on his iPhone 5S and
his iPad Air...

Last edited by wisecracker; 06-26-2014 at 04:47 PM.. Reason: See above...

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LEARN ABOUT CENTOS

pulse-client.conf

pulse-client.conf(5)						File Formats Manual					      pulse-client.conf(5)

NAME

       pulse-client.conf - PulseAudio client configuration file

SYNOPSIS

       ~/.config/pulse/client.conf

       /etc/pulse/client.conf

DESCRIPTION

       The  PulseAudio client library reads configuration directives from a file ~/.config/pulse/client.conf on startup and when that file doesn't
       exist from /etc/pulse/client.conf.

       The configuration file is a simple collection of variable declarations. If the configuration file  parser  encounters  either  ;  or  #	it
       ignores the rest of the line until its end.

       For the settings that take a boolean argument the values true, yes, on and 1 are equivalent, resp. false, no, off, 0.

DIRECTIVES

       default-sink=  The default sink to connect to. If specified overwrites the setting in the daemon. The environment variable $PULSE_SINK how-
       ever takes precedence.

       default-source= The default source to connect to. If specified overwrites the setting in the daemon. The environment variable $PULSE_SOURCE
       however takes precedence.

       default-server= The default sever to connect to. The environment variable $PULSE_SERVER takes precedence.

       autospawn= Autospawn a PulseAudio daemon when needed. Takes a boolean value, defaults to yes.

       daemon-binary= Path to the PulseAudio daemon to run when autospawning. Defaults to a path configured at compile time.

       extra-arguments= Extra arguments to pass to the PulseAudio daemon when autospawning. Defaults to --log-target=syslog

       cookie-file= Specify the path to the PulseAudio authentication cookie. Defaults to ~/.config/pulse/cookie.

       enable-shm= Enable data transfer via POSIX shared memory. Takes a boolean argument, defaults to yes.

       shm-size-bytes=	Sets the shared memory segment size for clients, in bytes. If left unspecified or is set to 0 it will default to some sys-
       tem-specific default, usually 64 MiB. Please note that usually there is no need to change this value, unless you are running an	OS  kernel
       that does not do memory overcommit.

       auto-connect-localhost=	Automatically try to connect to localhost via IP. Enabling this is a potential security hole since connections are
       only authenticated one-way and a rogue server might hence fool a client into sending it its private (e.g. VoIP call) data. This was enabled
       by default on PulseAudio version 0.9.21 and older. Defaults to no.

       auto-connect-display=  Automatically  try  to  connect  to the host X11's $DISPLAY variable is set to. The same security issues apply as to
       auto-connect-localhost=. Defaults to no.

AUTHORS

       The PulseAudio Developers <pulseaudio-discuss (at) lists (dot) freedesktop (dot) org>; PulseAudio is available from http://pulseaudio.org/

SEE ALSO

       pulse-daemon.conf(5), pulseaudio(1)

Manuals 							       User						      pulse-client.conf(5)