[alsa-devel] Strange Config: Fedora 8 running on Amazon EC2
I have a strange request (which is why I'm sending directly to the dev list). I'm trying to run Flash video (v9 or v10) on Firefox 3 on a Fedora 8 image running on Amazon EC2. I don't actually want/need sound (it's of course technically not possible, since EC2 doesn't provide a sound card). Video playback (when watched through VNC) goes fine for a couple minutes, but then the browser and flash lock up entirely. I've looked for ways to tell Firefox and/or Flash to not send audio out, but I've come up empty so far. So now I'm hoping that fixing this error and putting in perhaps some sort of "no op" device might help out.
I'm not positive the error is related to ALSA, though the fact that there appear to be a ton of the following logs just before the lockup is suspicious:
ALSA lib confmisc.c:768:(parse_card) cannot find card '0' ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory ALSA lib conf.c:3985:(snd_config_expand) Evaluate error: No such file or directory ALSA lib pcm.c:2144:(snd_pcm_open_noupdate) Unknown PCM default ALSA lib pcm_hw.c:1240:(_snd_pcm_hw_open) Invalid value for card
(these lines repeat over and over again until the crash happens, then it stops promptly)
As you can see by the alsa-info output at the following URL, I don't have any running snd modules:
http://www.alsa-project.org/db/?f=6b2431d0564b3638cdb798a6d1a21eb73982588c
Similarly, I don't have any sound-related devices installed (ie: /dev/audio, etc). My hope in emailing this list is that there may be a solution that causes ALSA to no-op the requests that Firefox/Flash send it's way, potentially solving the lockup I'm experiencing.
I would really appreciate any ideas that could be shared. Thank you very much!
Patrick
Hi,
On Wed, Jan 28, 2009 at 10:20 PM, Patrick Lightbody patrick@lightbody.net wrote:
I have a strange request (which is why I'm sending directly to the dev list). I'm trying to run Flash video (v9 or v10) on Firefox 3 on a Fedora 8 image running on Amazon EC2. I don't actually want/need sound (it's of course technically not possible, since EC2 doesn't provide a sound card). Video playback (when watched through VNC) goes fine for a couple minutes, but then the browser and flash lock up entirely. I've looked for ways to tell Firefox and/or Flash to not send audio out, but I've come up empty so far. So now I'm hoping that fixing this error and putting in perhaps some sort of "no op" device might help out.
I'm not positive the error is related to ALSA,
Neither am I -- but we can definitely give you the info you need to test out null playback to see if it helps. It could still be a video-related issue.
though the fact that there appear to be a ton of the following logs just before the lockup is suspicious:
ALSA lib confmisc.c:768:(parse_card) cannot find card '0' ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory ALSA lib conf.c:3985:(snd_config_expand) Evaluate error: No such file or directory ALSA lib pcm.c:2144:(snd_pcm_open_noupdate) Unknown PCM default ALSA lib pcm_hw.c:1240:(_snd_pcm_hw_open) Invalid value for card
(these lines repeat over and over again until the crash happens, then it stops promptly)
Yeah, you will want to eliminate such problems regardless of whether they are immediately fatal. The software (Flash) could have memory leaks or something if it fails to get a soundcard.
As you can see by the alsa-info output at the following URL, I don't have any running snd modules:
http://www.alsa-project.org/db/?f=6b2431d0564b3638cdb798a6d1a21eb73982588c
Similarly, I don't have any sound-related devices installed (ie: /dev/audio, etc). My hope in emailing this list is that there may be a solution that causes ALSA to no-op the requests that Firefox/Flash send it's way, potentially solving the lockup I'm experiencing.
Option 1 (less obvious unless you know where to look, but certainly viable): http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html <--- look up the "Null" plugin here. Drop a null plugin into /etc/asound.conf as the default:
pcm.!default { type null }
This is exactly the "no-op" soft PCM that you want. AFAIK all the APIs against this just return saying "OK, I've done it", and the configuration space is as flexible as possible.
Option 2, which was my first guess before I remembered the link above: You could install PulseAudio and either pipe the sound over the network to your host, or load a null sink, then use ALSA<->pulse.
Alternatively, you could provide "support" for no-op sounds from both PulseAudio _and_ ALSA clients by implementing both these options.
HTH,
Sean
I would really appreciate any ideas that could be shared. Thank you very much!
Patrick _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
Sean and Lee, Thanks for much for the ideas! A few moments ago someone on #lad on IRC suggested I try the snd-dummy module (modprobe snd-dummy). It worked like a champ - the log messages went away and the Flash component no longer crashed.
At least, on EC2's Fedora 8 instance.
Unfortunately, on another machine I need to get running (RHEL5), the logs continue to persist even when snd-dummy was installed. I will try both of your suggestions on that machine to see if it helps, but I just wanted to let you know about snd-dummy working out partially for me.
If you're curious, this is the alsa-info output for the RHEL machine:
http://www.alsa-project.org/db/?f=e8cc121e4c401a35969cd14e14b454c360037187
And this was on the one on the Fedora 8 machine (after having installed snd-dummy):
http://www.alsa-project.org/db/?f=b2153e21c6fe272a72e9bd97a91c46f6452a38f3
Patrick
On Wed, Jan 28, 2009 at 8:42 PM, Sean McNamara smcnam@gmail.com wrote:
Hi,
On Wed, Jan 28, 2009 at 10:20 PM, Patrick Lightbody patrick@lightbody.net wrote:
I have a strange request (which is why I'm sending directly to the dev list). I'm trying to run Flash video (v9 or v10) on Firefox 3 on a Fedora 8 image running on Amazon EC2. I don't actually want/need sound (it's of course technically not possible, since EC2 doesn't provide a sound card). Video playback (when watched through VNC) goes fine for a couple minutes, but then the browser and flash lock up entirely. I've looked for ways to tell Firefox and/or Flash to not send audio out, but I've come up empty so far. So now I'm hoping that fixing this error and putting in perhaps some sort of "no op" device might help out.
I'm not positive the error is related to ALSA,
Neither am I -- but we can definitely give you the info you need to test out null playback to see if it helps. It could still be a video-related issue.
though the fact that there appear to be a ton of the following logs just before the lockup is suspicious:
ALSA lib confmisc.c:768:(parse_card) cannot find card '0' ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name ALSA lib conf.c:3513:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory ALSA lib conf.c:3985:(snd_config_expand) Evaluate error: No such file or directory ALSA lib pcm.c:2144:(snd_pcm_open_noupdate) Unknown PCM default ALSA lib pcm_hw.c:1240:(_snd_pcm_hw_open) Invalid value for card
(these lines repeat over and over again until the crash happens, then it stops promptly)
Yeah, you will want to eliminate such problems regardless of whether they are immediately fatal. The software (Flash) could have memory leaks or something if it fails to get a soundcard.
As you can see by the alsa-info output at the following URL, I don't have any running snd modules:
http://www.alsa-project.org/db/?f=6b2431d0564b3638cdb798a6d1a21eb73982588c
Similarly, I don't have any sound-related devices installed (ie: /dev/audio, etc). My hope in emailing this list is that there may be a solution that causes ALSA to no-op the requests that Firefox/Flash send it's way, potentially solving the lockup I'm experiencing.
Option 1 (less obvious unless you know where to look, but certainly viable): http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html <--- look up the "Null" plugin here. Drop a null plugin into /etc/asound.conf as the default:
pcm.!default { type null }
This is exactly the "no-op" soft PCM that you want. AFAIK all the APIs against this just return saying "OK, I've done it", and the configuration space is as flexible as possible.
Option 2, which was my first guess before I remembered the link above: You could install PulseAudio and either pipe the sound over the network to your host, or load a null sink, then use ALSA<->pulse.
Alternatively, you could provide "support" for no-op sounds from both PulseAudio _and_ ALSA clients by implementing both these options.
HTH,
Sean
I would really appreciate any ideas that could be shared. Thank you very much!
Patrick _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
participants (2)
-
Patrick Lightbody -
Sean McNamara