Hi all:
I have a apinion about voice data, but I don't know
whether it is correct or not.
Please give me some comments.
If we type "hciconfig hci0 voice" and it will appear this on
my PC:
[root@bluez root]# hciconfig hci0 voice
hci0:
Type: USB
BD Address:
00:09:DD:xx:xx:xx ACL MTU: 192:8 SCO MTU:
64:8
Voice setting: 0x0060
(Default Condition)
Input Coding:
Linear
Input Data Format: 2's
complement
Input Sample Size: 16
bit
# of bits padding at MSB:
0
Air Coding Format:
CVSD
And my viewpoint is as below:
1. Input Coding :
Linear --> quantification and frequency are a ratio of
equality.
2. Input Data Format: 2's complement --> ???? I don't know
what's mean.
3. Input Sample Size: 16 bit --> per sample is used 16
bit to indicate.
4. Air Coding Format: CVSD --> Voice is sampled by
soundcard , then Baseband covert these data using CVSD codec and translate these
data on air.
As above, I give a conclusion:
I can extract voice datas
from SCO socket, and these data are coded by PCM (linear, 16 bit/per sample,
sample rate = 8k).
ex:
outgoing voice
data:
soundcard
sco socket
Baseband
|
|
|
| 8k sample
rate |
|
|
,16bit/sample |
|
voice
--->|-------------------->|----------->|---->CVSD
data
|
|
|
|
|
|
incoming voice
data:
Baseband
sco socket soundcard
Application
|
|
|
|
| linear PCM
|
| 8k sample rate
|
| ,16bit/sample
|
| 16 bit/sample |
CVSD
---->|------------------->|---------->|------------------->|---->analogy
voice
|
|
|
|
|
|
|
|
As
above , that are my concept, Is my concept correct?
Please give me some
comments.
Thank you .