Re: [pulseaudio-discuss] passthrough audio (eg. AC3 / DTS / WM9)
Just make sure PA doesn't grab the device, and then tell your app to use the low-level spdif-pass-thru directly. How that is configured has nothing to do with PA, and in fact stays exactly the same whether you run PA or not. You could use the device reservation utilities for this. When you have encoded data for pass through you can PA to let go off the device. See code in module-reserve - P ___ pulseaudio-discuss mailing list pulseaudio-discuss@mail.0pointer.de https://tango.0pointer.de/mailman/listinfo/pulseaudio-discuss
Re: [pulseaudio-discuss] passthrough audio (eg. AC3 / DTS / WM9)
On Mon, 05.10.09 05:11, Sean McNamara (smc...@gmail.com) wrote: I would surmise that PulseAudio is probably not for you if you want to do this. There is no optional mixing in PulseAudio; everything is mixed in software. I don't even know if PA has a way to tell client applications sorry, but the soundcard is being used excuslively by another PA client right now. Uh, not sure why this would be desirable, but if it is, it is very easy to write a module for this, probably not more than 20 lines or so. Unless we had some way to do software mixing on other encodings like AC3 and WM9 (we'd have to code up special cases of the mixing logic for _each_ supported format), supporting arbitrary audio data formats would be eliminating the usefulness of 99% of PA's existing modules and features, which expect PCM samples. Uh, not sure where you came up with 99%. Yes we currently only deal with PCM. But the parts dealing with PCM are limited nonetheless and the APIs can be extended to support encoded audio, too. As a matter of fact, it's relatively simple to write a daemon that accepts UNIX socket or TCP connections, reads audio data supported by a hardware decoder from the socket, and passes the data to ALSA. At least, I think it would be easier to develop such a daemon from scratch than it would be to modify PA to support what you're asking for. Uh. That is bogus. Encoded audio is in many ways just another type of audio. And hence it should be handled the same was as we already handle PCM. In fact, codec support in PA will come. Probably even in the near feature, as I started to hack on that on my train ride back from the BlueZ summit. In fact, at the BlueZ summit it became very clear that having codec support matters. We need it for SPDIF, we need it for HDMI, we need it for Bluetooth A2DP, we need it for UPnP AV/DLNA, we need it for embedded hw where there is specific sound hw that natively speaks codecs. So, it is not a question whether this will come, it's more a question when. The complexity in adding this stems from the fact that deducing timing information fromt the codec is not trivial. In fact the lower layers (alsa) don't really handle that properly either and for the PA case this becomes even more complex since we rely much more on that. Lennart -- Lennart PoetteringRed Hat, Inc. lennart [at] poettering [dot] net http://0pointer.net/lennart/ GnuPG 0x1A015CC4 ___ pulseaudio-discuss mailing list pulseaudio-discuss@mail.0pointer.de https://tango.0pointer.de/mailman/listinfo/pulseaudio-discuss
Re: [pulseaudio-discuss] passthrough audio (eg. AC3 / DTS / WM9)
On Mon, 05.10.09 14:30, Dave Moore (davewantsmo...@gmail.com) wrote: Hi Everyone. I'm really sorry if this has been covered before, I've read back through the past 6 months list history and found nothing and my OS (ubuntu) and application support forums/lists are not being very helpful. I would like to pass digital audio completely unaltered (bit-stream) to my SPDIF output - Can this be done with pulseaudio? No. Not at this time. (See other mails in this thread for what is planned) If you need ac3 pass-thru then you need to bypass PA. Just make sure you are not using the SPDIF port for PA (use g-v-c or pavucontrol and make sure the sound card is notconfigured for any of the 'digital iec985' modes). Lennart -- Lennart PoetteringRed Hat, Inc. lennart [at] poettering [dot] net http://0pointer.net/lennart/ GnuPG 0x1A015CC4 ___ pulseaudio-discuss mailing list pulseaudio-discuss@mail.0pointer.de https://tango.0pointer.de/mailman/listinfo/pulseaudio-discuss
Re: [pulseaudio-discuss] passthrough audio (eg. AC3 / DTS / WM9)
If you need ac3 pass-thru then you need to bypass PA. Just make sure you are not using the SPDIF port for PA (use g-v-c or pavucontrol and make sure the sound card is notconfigured for any of the 'digital iec985' modes). If you use AC3 pass-thru, what you are really sending over the SPDIF interface is a PCM stream. The AC3 content is formatted to follow the recommendations of IEC 61937: the compressed content uses 16 of the 24-bit words, there are additional headers and lots of padding with zeroes. In terms of timing, this is really PCM. You may need to set a number of control bits in the PCM interface but nothing serious. As long as you don't mix and don't modify the bitstream, you could handle pass-thru w/ PulseAudio without major modifications. Indeed things are completely different when the content is not reformatted to meet the PCM bitrate required by SPDIF (BT, MP3, etc). Cheers - Pierre ___ pulseaudio-discuss mailing list pulseaudio-discuss@mail.0pointer.de https://tango.0pointer.de/mailman/listinfo/pulseaudio-discuss
[pulseaudio-discuss] passthrough audio (eg. AC3 / DTS / WM9)
Hi Everyone. I'm really sorry if this has been covered before, I've read back through the past 6 months list history and found nothing and my OS (ubuntu) and application support forums/lists are not being very helpful. I would like to pass digital audio completely unaltered (bit-stream) to my SPDIF output - Can this be done with pulseaudio? (Yes, I understand that I will lose sound mixing and the ability to have multiple application use the sound device) For example: If I have a stereo PCM file @ 16bit / 44.1khz - Then output at this type (do not resample in any way) ... or PCM @ 24bit / 96khz etc. If I have AC3 / DTS @ 48khz - The output this original data exactly. (I am using an external decoder/processor and do not want the original audio data changed in any way). Again - sorry if this is a stupid question, or already answered. I could not find a definitive answer I would like to keep pulseaudio if possible - as it is what my Linux distro (ubuntu) has set default. Thanks in advance. ___ pulseaudio-discuss mailing list pulseaudio-discuss@mail.0pointer.de https://tango.0pointer.de/mailman/listinfo/pulseaudio-discuss
