Conversion from S16 format to ALAW

Conversion from S16 format to ALAW

[Manu Sharma]

Hi all,

I am trying to sample and play alaw streams on my iPAQ 5500. The HW 
driver registers support for S16_LE only. So, to achieve my purpose, I 
register a plugin like following in my alsa.conf file:

pcm.alaw {
	type alaw
	slave {
		pcm  "hw:0.0"
		format S16_LE
	}
}

With this, when I use arecord to capture sound, I get an error "arecord: 
set_params:832: Sample format not available".

Is there something wrong in my configuration setup or am I missing 
something ? Any clues or suggestions would be appreciated.

Regards,
Manu


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Re: Conversion from S16 format to ALAW

[Jaroslav Kysela]

On Tue, 16 Nov 2004, Manu Sharma wrote:

> Hi all,
> 
> I am trying to sample and play alaw streams on my iPAQ 5500. The HW 
> driver registers support for S16_LE only. So, to achieve my purpose, I 
> register a plugin like following in my alsa.conf file:
> 
> pcm.alaw {
> 	type alaw
> 	slave {
> 		pcm  "hw:0.0"
> 		format S16_LE
> 	}
> }
> 
> With this, when I use arecord to capture sound, I get an error "arecord: 
> set_params:832: Sample format not available".

Could you specify the full command? It should be something like:

arecord -D alaw -f A_LAW ...

Anyway, the default device should do this job for you also:

arecord -f A_LAW ...

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project, SUSE Labs


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Re: Conversion from S16 format to ALAW

[Takashi Iwai]

At Tue, 16 Nov 2004 08:59:05 +0100,
Manu Sharma wrote:
> 
> Hi all,
> 
> I am trying to sample and play alaw streams on my iPAQ 5500. The HW 
> driver registers support for S16_LE only. So, to achieve my purpose, I 
> register a plugin like following in my alsa.conf file:
> 
> pcm.alaw {
> 	type alaw
> 	slave {
> 		pcm  "hw:0.0"

Typo of "0,0"?

> 		format S16_LE
> 	}
> }
> 
> With this, when I use arecord to capture sound, I get an error "arecord: 
> set_params:832: Sample format not available".
> 
> Is there something wrong in my configuration setup or am I missing 
> something ? Any clues or suggestions would be appreciated.

I didn't get the error message.

	% arecord -Dalaw -traw -fA_LAW -c2 -r44100 foo.raw


Takashi


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Re: Conversion from S16 format to ALAW

[Manu Sharma]

Hi,

Thanks Jaroslav and Takashi for your questions; they served as inputs !

I was not explicitly specifying the format (-f A_LAW), considering that 
since the plugin type itself is "alaw". I missed the fact that I 
specified default format of this plugin to be S16_LE in my alsa.conf !

I have another question about the warning given in function header of 
snd_pcm_alaw_open (same applies for corresponding mulaw function).

Does the warning suggest that applications should not be using this 
function directly, they should instead configure their alsa.conf and use 
snd_pcm_open ?

Manu

Jaroslav Kysela wrote:
> On Tue, 16 Nov 2004, Manu Sharma wrote:
> 
> 
>>Hi all,
>>
>>I am trying to sample and play alaw streams on my iPAQ 5500. The HW 
>>driver registers support for S16_LE only. So, to achieve my purpose, I 
>>register a plugin like following in my alsa.conf file:
>>
>>pcm.alaw {
>>	type alaw
>>	slave {
>>		pcm  "hw:0.0"
>>		format S16_LE
>>	}
>>}
>>
>>With this, when I use arecord to capture sound, I get an error "arecord: 
>>set_params:832: Sample format not available".
> 
> 
> Could you specify the full command? It should be something like:
> 
> arecord -D alaw -f A_LAW ...
> 
> Anyway, the default device should do this job for you also:
> 
> arecord -f A_LAW ...
> 
> 						Jaroslav
> 
> -----
> Jaroslav Kysela <perex@suse.cz>
> Linux Kernel Sound Maintainer
> ALSA Project, SUSE Labs
> 
> 



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Re: Conversion from S16 format to ALAW

[Clemens Ladisch]

Manu Sharma wrote:
> I have another question about the warning given in function header of
> snd_pcm_alaw_open (same applies for corresponding mulaw function).
>
> Does the warning suggest that applications should not be using this
> function directly, they should instead configure their alsa.conf and use
> snd_pcm_open ?

Yes.  The way how alsa-lib creates plugins might change in the future.


HTH
Clemens



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