[MartinBrentnall]

Hi, I'm using XBMCbuntu on my Acer Revo 3610.

I'm using the HDMI output to my TV for video and audio when multiple people are watching. This works fine. When watching alone however, I want to use my headphones, which are connected to the S/PDIF optical output.

The problem is the optical audio is out of sync with the video. To be specific, I hear things about half a second before they occur on screen.

I understand this is because my TV is processing the picture to add motion smoothing, etc., which introduces input lag on the TV which obviously isn't present on the optical output. I know I can "solve" this by disabling the processing effects, but I like the processing effects and do not want to disable them.

I also know it's possible to manually sync the audio and video for each file I play. However, this is not a permanent change, and even if it were, it would make the HDMI audio out of sync, so it would need to be adjusted every time I switch between using headphones and TV audio.

So my question is this: Is there a way to permanently set a delay in only the optical audio output? Preferably this should be system-wide, but video only would also be acceptable. How can I do this?

Thanks

[thd042]

You may play around with the ALSA-plugins from ladspa. I have a similar problem with the analog out. This entry in ~/.asoundrc helped for the visual impact, though one can still hear a delay between TV output via HDMI and direct analog:

Code:

pcm.ladspa {
    type ladspa
    slave.pcm "plughw:0,0";
    path "/usr/local/lib/ladspa";
    plugins [{
        label  delay_5s
        input {
            controls [ 0.09 1.0 ]
        }
    }]
}

Not sure if a similar thing works for SPDIF, so please report back if you succeed.

[un1versal]

Wont alsa-plugins break xbmc?

[thd042]

Mmmh, not sure. According to my my experience not, but behavior is a bit unpredictable. Some settings worked, some were simply ignored. And I use an XBMC exclusive session, not as a normal user in a X-session, so there are not really other programs trying to do audio output.

Anyway, I always thought that pulseaudio is evil,but alsa is kind of OK?

[un1versal]

The point is, that 12.3 wont play well with Pulse in some configs, but ( ''ahem'' -> clears throat) v13 now supports Pulseaudio, so its not a evil vs ok situation anymore see PulseAudio (wiki)

You cant get HD audio for e.g out of Pulse since its doesn't support it (not xbmc limitation) , so even if now in v13 doesnt break its never going to be as good as alsa is until someone makes pulse catch up. For the op this may even do resolve it then idk.