[Bluez-users] SCO question ?

[Bluez-users] SCO question ?

[guang]

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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 .

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