WIP: USB audio output - N900 as an "audiophile" portable music player - Page 8 - maemo.org

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	Estel	2012-04-05 , 16:14
	Posts: 5,028 \| Thanked: 8,613 times \| Joined on Mar 2011	#71

Originally Posted by javispedro

It did work for me when I tried to do RTP over-the-network redirection (the quality and latency were not good though, the details should be in the two years-old pulseaudio network thread). I do not have USB speakers to test setting up another alsa sink in pulse though, so if the problem is that the kernel crashes (?) no idea.

Thanks, will read through pulseaudio thread.

By the way, IIRC, Oblomow or tried to check kernel crash logs after setting pulseaudio output to external DAC and getting instant reboot - no usable logs found:
http://talk.maemo.org/showpost.php?p...7&postcount=32

Maybe something was wrong there? Is there any way. that would help us determine exact case of problem? BTW, bfreemangordon, my question from:
http://talk.maemo.org/showpost.php?p...7&postcount=33

...still apply. Thanks in advance.

/Estel

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Last edited by Estel; 2012-11-02 at 06:37.

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indeo	2012-04-11 , 21:54
Posts: 18 \| Thanked: 13 times \| Joined on Jan 2011 @ NYC	#72

I ordered and received the recently released Fiio E17 DAV/Headphone Amp and have been using it with the N900. I've ordered a USB Micro B to Mini B Cable to see if I can connect it to the N900 using USB Host mode. If I'm able to connect it, and use the E17 as the audio output, I'll be able to take full advantage of the E17's nice Wolfson WM8740 DAC. This will require the N900 to be in USB host mode, and for there to be drivers for the E17 on the N900, and for there to be a way to select the E17 as the output sound device. I can then load FLAC files on the N900 and they will stream digitally to the E17

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	Estel	2012-04-12 , 06:03
	Posts: 5,028 \| Thanked: 8,613 times \| Joined on Mar 2011	#73

I'm 99,99% sure, that it will work with current modules found in kernel-power

Then, You may use smplayer as GUI for playing any mplayer-supported file via alsia external card output to as stated earlier in this thread - at least, until someone find solution to properly redirect pulseaudio's output.

/Estel

Last edited by Estel; 2012-04-12 at 06:06.

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	fpp	2012-04-12 , 20:28
	Posts: 2,853 \| Thanked: 968 times \| Joined on Nov 2005	#74

@Estel: I will top that, I'm 100% sure it will work :-)

@ineo : your use case is what I've been wanting to do all along (except that I'd hesitate between an E17 and the iBasso D-Zero, but that's irrelevant).
Everything that was said before applies : your E17 will be detected by h-e-n, just like my desktop DAC/amp and Estel's external sound card, as an ALSA device.

Streaming MP3/FLAC using software that can directly address that ALSA device is easy (using mplayer, MOC or smplayer as mentioned) but not seamless or very user-friendly.

The "way to select the E17 as the output sound device", at the system level and with Hildon apps that only use pulseaudio, is our biggest and still current problem. Nobody here seems to know how that thing really works (nobody interested in our project, at least :-)

I am beginning to fear that the problem will be solved on the Android side before we've made any progress on this. Some versions of Cyanogenmod 7 and 9 already enable USB sound on devices with host mode capability, and it's very probable that some upcoming minor release of Android 4.0x (ICS) will support it for good.

Poor old N900...

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	javispedro	2012-04-13 , 10:10
	Posts: 2,355 \| Thanked: 5,249 times \| Joined on Jan 2009 @ Barcelona	#75

Originally Posted by fpp

The "way to select the E17 as the output sound device", at the system level and with Hildon apps that only use pulseaudio, is our biggest and still current problem. Nobody here seems to know how that thing really works (nobody interested in our project, at least :-)

I did it two years ago without a single problem.

The instructions have been even posted here in this thread.

What is the problem?

EDIT: OK I am probably being overly optimistic. Any idea how could I simulate USB speakers easily?

Last edited by javispedro; 2012-04-13 at 10:18.

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Oblomow	2012-04-13 , 10:19
Posts: 72 \| Thanked: 184 times \| Joined on Apr 2011 @ Germany	#76

Originally Posted by javispedro

I did it two years ago without a single problem.

The instructions have been even posted here in this thread.

What is the problem?

The above describes only the result kirillkk got without the usb device connected. The whole picture is here. So "playback works" actually does not mean playback through usb.

When the usb device was connected & the driver loaded, the above procedure leads to a reboot.

EDIT:
could someone try the following:

Code:

sudo nice --8 gst-launch pulsesrc device=sink.hw0.monitor ! alsasink device=hw:1,0

with usb audio connected? This should give a higher priority to the task. It's still a waste of resources, as Estel pointed out, but as long as we don't have another working solution in place...

Last edited by Oblomow; 2012-04-13 at 10:33.

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	javispedro	2012-04-13 , 10:30
	Posts: 2,355 \| Thanked: 5,249 times \| Joined on Jan 2009 @ Barcelona	#77

Originally Posted by Oblomow

When the usb device was connected & the driver loaded, the above procedure leads to a reboot.

So that does not mean a kernel panic, it could very well be a watchdog or DSME reboot.

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	Estel	2012-04-14 , 01:52
	Posts: 5,028 \| Thanked: 8,613 times \| Joined on Mar 2011	#78

Originally Posted by javispedro

EDIT: OK I am probably being overly optimistic. Any idea how could I simulate USB speakers easily?

no idea other than using kernel module snd_dummy and trying to redirect pulseaudio sound there. Of course, it wouldn't be fake USB sound card, but maybe our problem will also manifest itself?

As for "real" simulate USB sound card, I have no idea :/

Originally Posted by javispedro

So that does not mean a kernel panic, it could very well be a watchdog or DSME reboot.

Any idea how to kick that bug in butt? you would probably look @ this Yourself, if You had access to USB sound device... Unless someone is willing to donate/lend even cheapest one, maybe one of us can do the debugging per Your instructions? I know it isn't most efficient way, but better than nothing

Thanks for Your help with this, anyway!

/Estel

// Edit

Wouldn't trying it with N900 in developer mode filter out/confirm watchdog/DSME reboot?

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retsaw	2012-04-17 , 14:13
Posts: 701 \| Thanked: 585 times \| Joined on Sep 2010 @ London, England	#79

I ordered myself a cheap USB soundcard just for testing, so I gave this a try

Originally Posted by kirillkk

I agree that it's a good idea to create a "usb audio" thread.
But the question was given in this thread so the answer follows.
I repeated the experiment with pulseaudio.
1.
Code:
pactl load-module module-alsa-sink-old sink_name=sink.hw2 device=hw:1  rate=48000 fragment_size=1920 fragments=4 alt_fragment_size=960 alt_fragments=2
2. pactl move-sink-input 2 7 (2 is nokia-music, 7 is newly registered sink)
3. playing music using maemo media player - nothing happens
no sound and it doesn't advance
4. pactl move-sink-input 2 2 (returned to normal setting) -
playback works
5. connected usb device
6. verified it works in moc
7. pactl move-sink-input 2 7
8. attempt to play music
9. device reboots

USB device is m-audio mobile pre. pulse configuration can be verified with pactl list. pactl is in pulseaudio-utils package

I've tried this and it works for me without reboot. I have disabled the dsme lifeguard by creating a /etc/no_lg_reboots file, you may need to reboot after creating this file, my N900 helpfully crashed (something to do with hostmode and the USB soundcard, but before I tried this) so I didn't get to test whether the creation of that file works without a reboot. I did it a little differently though, I first connected the USB soundcard and tested it, then I executed step 1, then I started music playback (with openmediaplayer) then I executed step 2.

EDIT:My N900 crashed after I stopped playback for a while, then tried to restart it. Got to go out now, will do more testing later.

Last edited by retsaw; 2012-04-17 at 14:17.

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retsaw	2012-04-17 , 19:53
Posts: 701 \| Thanked: 585 times \| Joined on Sep 2010 @ London, England	#80

I'm not sure why I was successful the first time I tried it, but I haven't been able to replicate that success. However, it wasn't dsme triggering the reboot, but one of the watchdogs, I put my N900 into R&D mode and disabled the watchdogs and now it just locks up for a while rather than rebooting, and I did at least get some interesting debug output in dmesg, I guess it is some sort of issue with the USB drivers that pulseaudio presumably triggers, I've attached the relevant dmesg output to this post and maybe someone will be able to make sense of it.

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