Re: [LAD] RME TCO option
On 08/25/2013 10:33 PM, Adrian Knoth wrote: On Fri, Aug 23, 2013 at 12:48:22PM +0100, Chris Goddard wrote: Hi Adrian Hi! Let me CC Robin and LAD on this one. Hope you don't mind me contacting you directly, but I have a question regarding the RME TCO option and how it is supposed to work. I saw your name on some ALSA commits relating to the TCO recently and thought you would at least be the right person to start by asking. The TCO can read ltc, but once it has done that how does it communicate that time information tothe user space ? If I was, say, running Ardour and wanted it to chase this ltc what would Ardour need to do to make use of it ? can't say how you get at the TCO input, but thanks to robin's recent work, ardour can chase an incoming smpte ltc signal. it is just another audio signal, connected to ardour's ltc input port. fwiw, you don't need a TCO to chase LTC at all. the TCO is interesting if you want to generate LTC in hardware, or if you want to _sync_ to LTC, i.e. recover a clock signal from it. -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] RME TCO option
On 28/08/13 11:17, Jörn Nettingsmeier wrote: On 08/25/2013 10:33 PM, Adrian Knoth wrote: On Fri, Aug 23, 2013 at 12:48:22PM +0100, Chris Goddard wrote: Hi Adrian Hi! Let me CC Robin and LAD on this one. Hope you don't mind me contacting you directly, but I have a question regarding the RME TCO option and how it is supposed to work. I saw your name on some ALSA commits relating to the TCO recently and thought you would at least be the right person to start by asking. The TCO can read ltc, but once it has done that how does it communicate that time information tothe user space ? If I was, say, running Ardour and wanted it to chase this ltc what would Ardour need to do to make use of it ? can't say how you get at the TCO input, but thanks to robin's recent work, ardour can chase an incoming smpte ltc signal. it is just another audio signal, connected to ardour's ltc input port. fwiw, you don't need a TCO to chase LTC at all. the TCO is interesting if you want to generate LTC in hardware, or if you want to _sync_ to LTC, i.e. recover a clock signal from it. Right, and I was involved with Robin in adding that capability to Ardour. But, this doesn't help with something like an RME MADI card, that doesn't have any analogue inputs, where do you inject the LTC ? I also think the offloading of the processing of the LTC would be useful. -- Cheers Chris ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] RME TCO option
On Fri, Aug 23, 2013 at 12:48:22PM +0100, Chris Goddard wrote: Hi Adrian Hi! Let me CC Robin and LAD on this one. Hope you don't mind me contacting you directly, but I have a question regarding the RME TCO option and how it is supposed to work. I saw your name on some ALSA commits relating to the TCO recently and thought you would at least be the right person to start by asking. The TCO can read ltc, but once it has done that how does it communicate that time information tothe user space ? If I was, say, running Ardour and wanted it to chase this ltc what would Ardour need to do to make use of it ? To be honest: I don't know, I've only fixed the kernel side of it. ;) There are 1.5 ways to read the TCO's LTC output from userspace: 1. Via ioctl. Needs currently unreleased alsa-lib containing my commit 4b169b05b48f4ea0196879b62b8c3fa5b050e806 and newest driver, Takashi's sound-2.6 is fine. Then, use SNDRV_HDSPM_IOCTL_GET_LTC. To the best of my knowledge, that's the proper way to read the LTC and it's what I've fixed. 2. If the TCO is present, we create a MIDI output port sending the MTC. At least I think it's MTC. Since the data is directly generated by the TCO, the driver has no influence on it. No idea if it helps in your case if you set this port as the MTC input port in Ardour. So it looks like for proper LTC support, we either need some converter (maybe there already is one?) or ardour needs to be augmented. I have absolutely no idea what the preferred approach is, but I'm sure Robin or Paul do. Maybe it's easiest to add another input path to one of Robin's LTC libs that just runs the appropriate ioctl and parses the output. Since the LTC is already decoded by the TCO, it should be pretty straight-forward. Oh, and last not least: I don't own a TCO, so I cannot really test anything. Fortunately, the ioctl is purely software, so a mockup should do the trick. Cheers -- mail: a...@thur.de http://adi.thur.de PGP/GPG: key via keyserver ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
