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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'>Hi
everybody,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'>I
have been using speex-1.2beta1 and my input data is 8-bit unsigned so I know that
I should convert from 8 to 16 bits. I’ve done the convertion as following.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>for(int
i=0; i<160; ++i)<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:35.4pt;text-autospace:none'><font size=2
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>{<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'> input_frame[i]
= (short)( (data[2*i] << 8) | data[2*i+1]);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'> }<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'>When
my codec application didn’t work right, I think that the reason is an
error at this convertion. For this aim, I looked at read_samples function in
speexenc project and I can’t understand why the convertion is done in
this way:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'>
for(i=frame_size*channels-1;i>=0;i--)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'> {<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'>
s[i]=(in[i]<<8)^0x8000;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'> }<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'>(in
my application, channels is 1 and frame_size=160)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt'>I can
understand why shift left 8, but can’t why we should do XOR operation with
1000 0000 0000 0000. Should I do the convertion operation so and why? Please can
you </span></font><span lang=EN-US>clarify? Thanks a lot for your helps.<o:p></o:p></span></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-US style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-US style='font-size:
10.0pt'>Sincerely<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-US style='font-size:
10.0pt'>Yasemin</span></font><o:p></o:p></p>
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