[wdmaudiodev] Re: Audio data conversion in apps?
- From: "Bob Johnston" <Bob_Johnston@xxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 23 Sep 2002 15:00:06 -0400
Hi Chris,
Maybe cool edit looking for a WAVEFORMATEX header preceding the RAW PCM =
describing the format of the data?
Bob Johnston
-----Original Message-----
From: Chris Edgington [mailto:chris.lists@xxxxxxxxxxxxxxxxxxxxxxxx]
Sent: Monday, September 23, 2002 2:18 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Audio data conversion in apps?
Hello. I'm new to the WDM audio world. I'm working with a device that
really isn't an audio device, it's a conduit for transporting audio
data. I've been tasked with debugging some problems with the audio
driver written for the device. One problem I have is that of audio data
manipulation by applications. I'm using CoolEdit for my testing, on
Win2K. In order to have a known dataset, I created a binary file full of
0xB0 values. I then imported that file as raw PCM into CoolEdit, as 8bit
unsigned data. The driver is configured to receive 8bit data. So, I
expected to receive all 0xB0 values when playing back the file through
the driver. But, I receive 0x99 instead of 0xB0. After hitting stop, the
driver gets a string of 0x80 values, I assume to silence things out
(since 0x80 is silence in 8bit unsigned world). Anybody know what
parameters / algorithm is being used for the data conversion and why
CoolEdit is not sending me the 0xB0 I imported? I also tried this with
Audacity, the open-source app for windows. It send 0x9B instead of 0xB0.
I'm going to start reading through the source for it to see how it goes
from my imported data to what it sends me .... but thought I'd ask here
to see if someone can explain.
Thanks,
-Chris
Awesome Software & Consulting
http://www.thatsawesomesoftware.com
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