Re: usb-audio

[Takashi Iwai <tiwai@suse.de>]

At Tue, 28 Oct 2003 11:41:07 +0100,
Niklas Werner wrote:
> 
> Am Dienstag, 28. Oktober 2003 11:11 schrieb Takashi Iwai:
> > At Mon, 27 Oct 2003 20:53:08 +0100,
> >
> > Antonio Willy Malara wrote:
> > > On 2003.10.27 19:16, Takashi Iwai wrote:
> > > > > 	/* FIXME: correct endianess and sign? */
> > > >
> > > > could you give more information:
> > > > which program, which device and what format doesn't it work?
> > >
> > > the system is a powermac, the device is a Griffin iMic, the app is
> > > jack version 0.80, the output is:
> > >
> > > Sorry. The audio interface "hw:1"doesn't support either of the two
> > > hardware sample formats that jack can use.
> >
> > then it's a problem of JACK, not ALSA.
> > the hardware doesn't support 32bit integer but only 24bit packed in 3
> > bytes.
> No, I don't think it is.
> I get similar problems with my emi 2|6 and alsaplayer, mplayer, xmms, ...
 
did you use plughw instead of hw in all cases?
otherwise they won't work always.


> My impression is that ALSA assumes that the connected interfaces _always_ 
> allow for the same Endianess as the system. This, of course, isn't always 
> so.
> Mplayer:
> 
> Checking audio filter chain for 44100Hz/2ch/16bit -> 44100Hz/2ch/16bit...
> AF_pre: af format: 2 bps, 2 ch, 44100 hz, big endian signed int 
> AF_pre: 44100Hz 2ch Signed 16-bit (Big-Endian)
> alsa-init: requested format: 44100 Hz, 2 channels, Signed 16-bit 
> (Big-Endian)
> alsa-init: soundcard set to emi
> alsa-init: format Signed 16-bit (Big-Endian) are not supported by 
> hardware, trying default

so, mplayer likely uses hw layer.

mplayer has an option to specify the device name.
it'd be better to define a new pcm in ~/.asoundrc such as

	pcm.emi26 {
		type plug
		slave.pcm "hw:0"
	}

(where "hw:0" should be changed to the corresponding one)

and run like

	% mplayer -ao alsa9:emi26 ...
		
> alsa9: 44100 Hz/2 channels/4 bpf/65536 bytes buffer/Signed 16 bit Little 
> Endian
> AO: [alsa9] 44100Hz 2ch Signed 16-bit (Little-Endian) (2 bps)
> 
> alsaplayer either dies with "FIXME: f_unsynchronization is set.Please 
> contact alsaplayer team." or produces static noise.

it sounds like a different one.  but, at least, the above FIXME should
be the alsaplayer problem.

> aplay does get this right, so it seems to use a different method of 
> querying the device.

then i guess using plug layer would solve the problem in most cases.


Takashi


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