[Asterisk-video] if2 bit stuffing in app_h324m

[Francesco Emmi]

Klaus Darilion wrote:

>> b243 = buf[31] & (1 << 5)
>> b244 = buf[31] & (1 << 4)
> 
> I guess the end should be following (as we start from 0):
> 
> b242 = buf[31] & (1 << 5)
> b243 = buf[31] & (1 << 4)

Sure!

>> if2[0] = ((b3 b2 b1 b0 )& 0xF0) | (mode & 0x0f) = (REV(buf[1]) & 0xF0) | 
>>   (mode & 0x0f)
> 
> Thus, if2 does not use network bit order? Or is it only h324m which does 
> not use network bit order?
> 
> Now I know how it is done - but why? Is this somewhere specified in 
> standard?
> 
> btw: Why is the mode not bit-reversed? If it is about bit order in 
> general I would think that "mode" must be reversed too?

No. Mode must not bit reversed. About standards and reason of bit order 
I can't answer you. To be honest when dealing with amr stuff we found 
that it is difficult to retrieve informations from specifications (or at 
least I had no much time to do it...) and helped ourselves by looking 
directly h223 dumps coming from 3g mobiles.

Greetings
Francesco

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Francesco Emmi
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