Thanks for your input, Colin. 2011/8/1 Colin Guthrie <gmane at colin.guthr.ie>: > Dynamic profile switching is not currently supported, but it will be in > the future. OK, that is good to know. > At present we're concentrating on passthough as that's generally what > people have asked for more and it it semi related to this issue. Yeah, passthrough is important to me as well. Probably more important than profile switching :). Right now I have to use plain-ALSA for this. > 2. Media Player requests DTS passthrough -> PA Rejects as the user has > not said their receiver supports it. > ?Media Player requests AC3 passthrough -> Ditto > ?Media Player requests 6 channel PCM surround -> PA Switches to the AC3 > Profile and accepts 6ch PCM input. That sounds good to me. > As you can see the negotiation becomes far more complex... in step three > above, why would PA prefer the 5.1 AC3 over the 5.1 Analog for example? Well in my case I am using a HDMI connection and my graphics card only supports either 2-channel PCM or DTS/AC3 passthrough. This is why I have to use the PCM-to-AC3 conversion for multichannel PCM. Obviously this would not make sense for 2-channel PCM sources. If the device would be able to accept 6 or 8 channels directly this should be preferred over AC3 encoding. But I guess users would not use the a52-plugin in such a setup anyway. > At the moment, I'm not massively in favour of doing automatic profile > switching at all and rather just dealing more gracefully with the > disabling of upmixing. The AC3 encoder output is a bit of a stick in the > mud here tho', as it's got a kind special use case... I'm not really > sure how best to deal with that one :s I understand. In the long-term I would probably be fine with this, as newer graphics cards support multichannel PCM directly. I have also found a solution I can live with: for applications which require multichannel PCM I simply use ALSA and redirect them to pulse through the "pcm.!default"-section in my .asoundrc. But in "the pcm.!surround51"-section I am still defining the a52-encoding directly. This kinda works and since I do not use multichannel material every day I am fine with it. - Frederik
