Re: [Bluez-devel] What endian type is supported by audio device ?

[Marcel Holtmann <marcel@holtmann.org>]

Hi Mayank,

> Don't you think that we should first find out which
> endian type the user's audio device supports ?
> 
> I mean, in the file sbc.c in the following lines
> 
> for (i = 0; i < samples; i++) {
> 	for (ch = 0; ch < priv->frame.channels; ch++) {
> 		int16_t s =
> (int16_t)(priv->frame.pcm_sample[ch][i]);
> 		*ptr++ = (s & 0xff00) >> 8;
> 		*ptr++ = (s & 0x00ff);
> 	}
> }
> 
> Shouldn't we first check out whether the user's audio
> device supports little endian or big endian type ?
> 
> It should be something like below...
> 
> for (i = 0; i < samples; i++) {
> 	for (ch = 0; ch < priv->frame.channels; ch++) {
> 		int16_t s =
> (int16_t)(priv->frame.pcm_sample[ch][i]);
> 		if(BIG_ENDIAN) {
> 			*ptr++ = (s & 0xff00) >> 8;
> 			*ptr++ = (s & 0x00ff);
> 		}
> 		else {
> 			*ptr++ = (s & 0x00ff);
> 			*ptr++ = (s & 0xff00) >> 8;
> 		}
> 	}
> }
> 
> Ofcourse BIG_ENDIAN will be replaced by a function or
> macro which returns the endian type.
> 
> Do you have knowledge of such a function or macro ?
> If yes, please patch sbc.c file for us.
> 
> It will be great for people like me who have spent
> weeks in figuring out why the sound quality is so poor
> while using sbcdec.c
> 
> I use an Intel based machine, which follows
> little-endian format.
> But sbc.c was using big endian format.

actually this has nothing to do with the machine type. It depends on the
endian format of the input PCM stream. So we should add a flags that
tells us about the endian format of the input.

Regards

Marcel




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