Re: [Linphone-users]Sound card 8 bits

[Simon Morlat]

Le lun 16/12/2002 à 15:58, Stephane List a écrit :
> Hello,
> 
> I'm using a sound card that as only one channel of 8 bits for the micro.
> In the code of mediastreamer, I've seen that it must always be a 16
> bits.
> 
> If I modify the mediastreamer code to initialise my sound card with 8
> bits mono, will it work ? What are the codec (speex, G711...) that can
> do 8/16 bits ?
Hi,

All codecs must work with 16 bits... You have to modify the MSSoudRead
and MSSoudWrite code to do a conversion from your 8bits to 16bits, like
this:
char *buffer8;
gint16 *buffer16;

for(i=0;i<size;i++)
        buffer16[i]=  ((gint16)buffer8[i]) << 8;

The quality won't be very good...

PS: it assumes that your card is giving you 8bit linear PCM, not 8bit
Mulaw or Alaw.

Simon



> 
> Thanks
> 
> Stephane
> 
> PS : I'm using an integrated audio codec in a geode processor, so I can't
> change my soundcard :-<
-- 
Simon Morlat <address@hidden>