On 02.09.2009 07:49, John Robinson wrote:

I would very much like to hear the main programme's soundtrack and the audio description track at the same time, but at the moment, I can only hear one or the other - not both.

Hmmm, interesting task. However, I don't think that this is possible currently. Output devices are currently designed to handle one audio channel, not multiple at the same time. Mixing them to one would require decompressing and re-compressing them and would probably introduce timing issues.

There may be a quirked solution like playing back the second channel externally, like connecting to it using mplayer+streamdev, however thats not very comfortable.

The best solution is probably a dedicated plugin that connects to live view and plays the secondary audio track in parallel. However I don't think that such a plugin exists currently.

Cheers,

Udo

Hi,

John Robinson schrieb:

One member of this list very helpfully suggested that, to switch between the programme's main sound track and the audio description track, I can hit the 'Audio' key, then the right cursor key and then the 'Audio' key again. This does, indeed switch from the main programme sound track to the audio description track, but it only lets me hear one or the other, not both.

Maybe I told you too much details of the audio menu so you got a bit confused. Your key sequence 'Audio', 'right cursor', 'Audio' may indeed do, what you experience. Let me explain:

1.) 'Audio' opens the audio menu. 2.) 'right cursor' selects the right channel of the current stereo track. 3.) 'Audio' switches to the next track (audio description) but stays at right channel of the audio description track.

At the moment, there is no programme running where I could verify my conclusions, but for me it looks like that (referencing the explanations of my previous email): the audio description track provides two mono channels which appear as left and right channel of the stereo audio description track. The left channel seems to provide a mono audio signal of the main programmes sound track, while the right channel provides audio description only.

So simply omitting step two 'right cursor' from your key sequence should do the trick and present both mono channels at the same time. The only drawback of the current solution is, that you hear the main programme sound track only on the left side of your audio equipment and the audio description only on the right side.

Mixing both mono channels together and presenting the result as a stereo signal is feasible by output plugins but would require some way to tell the output plugin to activate this mode. The best would be if VDR's user interface would allow to select such a mode and provide that selection to the output plugin.

Suggestion for extending the user and output plugin interface: In the audio menu, the left and right keys select between left, stereo and right channel. A further mode 'combined' should be added which can be reached by pressing 'right' when the right channel is selected. The current audio channel selection is provided in the output plugin interface via the method SetAudioChannelDevice. The parameter values 0, 1 or 2 represent stereo, left or right channel. A further parameter value 3 would represent 'combined' mode. For compatibility and the most common use case, 'combined' mode should need to be activated in VDR's setup menu, i. e. it is not available by default.

Maybe Klaus can drop a few words about this extension.

Bye.