Thursday, August 23, 2007

Pulse Audio On HP Thin Clients

Yesterday we had a conference call with HP and worked out a plan to have Pulseaudio built and installed on our HP t5725 thin clients. This was always a phase 2 goal, and now that the thin clients are installed, this is my primary project. I have been impressed with Pulse so far. Sound on Linux is horribly inconsistent (Alsa, OSS, ESD and NAS anyone?) and difficult to deploy. Various applications support different sound libraries, and what Pulse does is support enough of them to allow most things to just work. We hope to deploy this sometime in October or November.

Here is the only change I had to make so far:
protocol-esound.c
74c74
< #define MAX_CACHE_SAMPLE_SIZE (1024000) ---
> #define MAX_CACHE_SAMPLE_SIZE (2048000)

Increasing this cache allowed the standard login.wav GNOME sound file to play over Esound. Some of these probably should be environmental variables or settings, so that they do not require a recompile.

Our biggest sound requirements have been resolved:
Esound handles GNOME login sounds and other Linux applications
OSS is handled with the padsp binary, this allows Citrix clients to play all of the sounds from Microsoft Windows apps.
PulseAudio is handling the shockwave plugin in Firefox, and also works natively with Xine to allow playback of Windows Media, Quicktime and Real content. For grins I'm also testing remote display of TV tuners and DVD playback.

Here is a simplified diagram of multiple servers and applications all redirecting sound to the thin client and it coming out the attached speakers.

18 comments:

Anonymous said...

I recently wondered how video playback on a remote X server would perform, but didn't conduct any experiments myself, so how are the framerates, latencies, tearing, dropped frames, etc. In short is it anywhere near enjoyable?

Dave Richards said...

Video clips that are compressed, play OK and aren't bad (Real, Quicktime, Windows Media). Compiz slows them down, and will need some tuning in the future. TV plays fine over remote display, in fact I have been able to get full screen TV with zapping to remote display. DVDs however right now are pokey, and I'm just starting to experiment with some tuning.

Sound is working fine from all sources with pulse.

Joe Baker said...

I've seen dvd video content broadcast streamed over a network using vlc (video lan client) I worked quite well. Wireless is problematic, because of increased error rates, different transmission rates, etc... Still it sort of worked.

Anonymous said...

presently taking red hat c.e. courses in the wash. d.c. area and relocating to pinellas county, fl. area-( any openings coming up with org.?)Visited largo in fall 2006, where i first heard about the city of largo and their linux implementation- I am just fascinated!!!

Anonymous said...

Dear Dave, is it possible to make Pulse Audio work with Ubuntu 6.06LTS/LTSP4.2?

There is now Pulse Audio's dev-libraries for Ubuntu 6.06, so I think it does not work. Maybe it's just me...

I have 2 servers with 120 cliets, 30 t5125 and 80 t5135.

http://www.arkki.info/?p=7

I can use esd-sounds (xmms, etc), but not Flash 9.

And we do not use 3D-desktops ;-).

Best regards Asmo, Kokkola, Finland.

Anonymous said...

Dave, forget my question. I have my answer.

http://marc.info/?l=ltsp-discuss&m=118845703911812&w=2

Best regards Asmo Koskinen.

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