[Bug 192888] Re: firefox crashes on flash contents when using libflashsupport

Conn connogriofa at gmail.com
Wed Aug 13 04:16:29 UTC 2008

** Description changed:

  use pulseaudio and libflashsupport together with flashplugin-nonfree in
  1. navigate to youtube video
  2. wait till sound plays
  3. hit back button
  4. hit forward
  5. goto 2 if not yet crashed.
  the crash sometimes happens after 2 iterations ... and i can't remember
  that i ever made 10 :) ...
  Tested on two machines both with gutsy and hardy (on 32 bit x86): flash
  content very often crashes firefox (both of firefox-3.0 in hardy and
  older versions). I've just tried with other browsers, epiphany-browser
  crashes as well, and even konqueror from KDE (though it's not crashing
  at a whole, since it may run flash and other plugins as another user or
  something similar - I think at least - but it reports the crash of
  flash). I don't know exactly the package I should report this against,
  but as far as I can remember this issue presents since I started to play
  with pulseaudio: there is a wrapper lib to allow flash to play sound via
  PA right, so it CAN BE caused by this single issue instead of problem of
  the browser or the flash plugin itself?
  Workaround for early Hardy adopters:
  Manually uninstall the libflashsupport via 'apt-get remove
  libflashsupport' or synaptic.  This is necessary because libflashsupport
  would not automatically be removed by update-manager when it was changed
  from a dependent package to a recommended package during the Hardy
  development cycle.
+ =================
+ Update 13/8/08: Hopefully this summary can help clarify the situation and help get this bug fixed!
+ Since the release of Flash 9, ALSA is the only audio output method
+ supported by Flash (as opposed to earlier releases which had OSS and ESD
+ support built-in). However, to aid with backwards-compatibility, Adobe
+ have provided a simple API to support other audio (and secure
+ transaction) schemes, which can be exposed by using the
+ "libflashsupport" code. You can view the original implementation on
+ Adobe's wiki page, which extends OSS and ESD output to Flash 9:
+ http://labs.adobe.com/wiki/index.php/Flash_Player:Additional_Interface_Support_for_Linux
+ The version of libflashsupport used in Ubuntu (and most recent
+ distributions that use PulseAudio) is different to the above, as it has
+ been extended to support PulseAudio. You can see the relevant upstream
+ wiki, with a description and link to the git repository:
+ http://www.pulseaudio.org/wiki/FlashPlayer9Solution
+ The problem that users are experiencing in this bug is that Flash
+ becomes unstable when the libflashsupport API is used; both the original
+ OSS/ESD implementation provided by Adobe and the version adapted for
+ PulseAudio exhibit this instability. The source of the problem is within
+ Flash itself and it is not due to a bug in the modified libflashsupport
+ code. See this PulseAudio bug report:
+ http://www.pulseaudio.org/ticket/267
+ So what can we do? We can drop libflashsupport entirely and use a better
+ method to enable PulseAudio support in Flash (and all ALSA applications,
+ in fact). PulseAudio provides ALSA plugins that enable most ALSA
+ applications to have PulseAudio support. Unfortunately, Ubuntu is one of
+ the few distributions that did not configure PulseAudio completely and
+ thus ALSA applications completely bypass PulseAudio, causing mixing
+ conflicts. This issue is reported on bug #198453 and you can read the
+ FAQ at the following link for a summary of the problem here:
+ http://ubuntuforums.org/showthread.php?t=866965
+ If we remove libflashsupport and fix bug #198453, there's "good news"
+ and "bad news" with regards to Flash:
+ The bad news: Flash 9 still won't work (due to Flash 9's erroneous
+ reliance on snd_async_add_pcm_handler() which causes problems with the
+ PulseAudio ALSA plugin). See the PulseAudio developer's comment on Flash
+ 9 here: https://tango.0pointer.de/pipermail/pulseaudio-
+ discuss/2008-May/001796.html
+ The good news: the snd_async_add_pcm_handler() issue is fixed in Flash
+ 10 (since beta 1). Essentially, Flash 10 is 100% PulseAudio compatible
+ when using the proper configuration of bug #198453.
+ In summary, the solution to this bug:
+ 1. Upgrade to Flash 10 (at release candidate status as of 13/8)
+ 2. Drop libflashsupport completely (it causes instability in Flash 9 and 10)
+ 3. Fix bug #198453
+ This bug is a trivial fix for Intrepid (and should have been fixed a
+ long time ago, to give PulseAudio time for testing). It is also possible
+ to fix in Hardy, as long as the prerequisites of bug #198453 can be
+ fulfilled whilst keeping the SRU policy for an LTS release in mind.
+ Either way, *something needs to be done*.

firefox crashes on flash contents when using libflashsupport
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