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Commit cac19c3b authored by Thibault Le Meur's avatar Thibault Le Meur Committed by Jaroslav Kysela
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[ALSA] usb-audio - Fix AC3 with M-Audio Audiophile USB 



Fixed AC3 interface in device_setup=0x00 mode thanks to Hakan
Lennestal and updated documentation

Signed-off-by: default avatarThibault Le Meur <Thibault.LeMeur@supelec.fr>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarJaroslav Kysela <perex@suse.cz>
parent 1b290a51

Documentation/sound/alsa/Audiophile-Usb.txt

+16 −6
Original line number Diff line number Diff line 
	Guide to using M-Audio Audiophile USB with ALSA and Jack	v1.4

	Guide to using M-Audio Audiophile USB with ALSA and Jack	v1.5

	========================================================



	    Thibault Le Meur <Thibault.LeMeur@supelec.fr>
@@ -12,6 +12,8 @@ History 
 - Added Low Endianness nature of 16bits-modes

   found by Hakan Lennestal <Hakan.Lennestal@brfsodrahamn.se>

 - Modifying document structure

* v1.5 - Thibault Le Meur (2007-07-12)

 - Added AC3/DTS passthru info





1 - Audiophile USB Specs and correct usage
@@ -105,9 +107,12 @@ way (I suppose the device's index is 1): 


In this mode, the device uses Big Endian byte-encoding so that 

supported audio format are S16_BE for 16-bit depth modes and S24_3BE for 

24-bits depth mode. One exception is the hw:1,2 port which is reported 

to be Little Endian compliant (supposedly supporting S16_LE) but processes 

in fact only S16_BE streams.

24-bits depth mode.



One exception is the hw:1,2 port which was reported to be Little Endian 

compliant (supposedly supporting S16_LE) but processes in fact only S16_BE streams.

This has been fixed in kernel 2.6.23 and above and now the hw:1,2 interface 

is reported to be big endian in this default driver mode.



Examples:

 * playing a S24_3BE encoded raw file to the Ao port
@@ -116,6 +121,8 @@ Examples: 
   % arecord -D hw:1,1 -c2  -t raw -r48000 -fS24_3BE test.raw

 * playing a S16_BE encoded raw file to the Do port

   % aplay -D hw:1,1 -c2 -t raw -r48000 -fS16_BE test.raw

 * playing an ac3 sample file to the Do port

   % aplay -D hw:1,2 --channels=6 ac3_S16_BE_encoded_file.raw



If you're happy with the default Alsa driver mode and don't experience any 

issue with this mode, then you can skip the following chapter.
@@ -205,13 +212,16 @@ mode" above for an aplay command example) 


3.2.1.3 - AC3 w/ DTS passthru mode



This mode is untested, I have no AC3 compliant device to test it. I uses:

Thanks to Hakan Lennestal, I now have a report saying that this mode works.



 * device_setup=0x03

   - 16bits 48kHz mode with only the Do port enabled 

   - AC3 with DTS passthru (not tested)

   - AC3 with DTS passthru

   - Caution with this setup the Do port is mapped to the pcm device hw:1,0



The command line used to playback the AC3/DTS encoded .wav-files in this mode:

   % aplay -D hw:1,0 --channels=6 ac3_S16_LE_encoded_file.raw



3.2.2 - How to use the device_setup parameter

----------------------------------------------

sound/usb/usbaudio.c

+12 −1
Original line number Diff line number Diff line
@@ -2532,7 +2532,18 @@ static int parse_audio_format_i(struct snd_usb_audio *chip, struct audioformat * 
		 *        but we give normal PCM format to get the existing

		 *        apps working...

		 */

		switch (chip->usb_id) {



		case USB_ID(0x0763, 0x2003): /* M-Audio Audiophile USB */

			if (device_setup[chip->index] == 0x00 && 

			    fp->altsetting == 6)

				pcm_format = SNDRV_PCM_FORMAT_S16_BE;

			else

				pcm_format = SNDRV_PCM_FORMAT_S16_LE;

			break;

		default:

			pcm_format = SNDRV_PCM_FORMAT_S16_LE;

		}

	} else {

		pcm_format = parse_audio_format_i_type(chip, fp, format, fmt);

		if (pcm_format < 0)