Le vendredi 19 août 2016, 12:16:57 Arun Raghavan a écrit : > On Fri, 19 Aug 2016, at 01:29 AM, Pierre-Louis Bossart wrote: > > On 8/18/16 11:43 AM, Rémi Denis-Courmont wrote: > > > Hello, > > > > > > For a number of years already, PulseAudio has supported a concept of > > > sink > > > inputs with multiple formats. That is meant to support S/PDIF output in > > > addition to PCM. > > > > > > One thing I´m wondering... what is the expected behaviour for an > > > application to negotiate non-PCM format for a stream? Specifically, if > > > the application supports IEC 61937, should it always offer the relevant > > > format (in addition to PCM fallback) when creating the stream? Or > > > should it do so only if the user has somehow enabled that feature? > > > > > > In other words, is PulseAudio supposed to know if IEC 61937 will > > > actually > > > work, or is it merely naively listing the formats that the sound card > > > allows, without regards to adequate speaker presence? > > > > The sound card itself only pushes the compressed format on HDMI or > > SPDIF, it doesn't really know what formats are embedded in the payload. > > To know what the receiver supports once can read the EDID/ELD > > information, but this is only for HDMI/DP and not for SPDIF, and it's > > often corrupted/invalid. If I remember well the solution is to let the > > user specify what formats work rather than guessing or relying on > > invalid data. Well, yeah. That's why I'm asking :) My question is more, where/how do we expect the user to configure this. Obviously (sadly) it needs to be configured manually somewhere. > That's correct. We do not offer these formats on the sink unless the > user has explicitly signalled that they are available (via options in > pavucontrol or via pactl on the command line). So the design assumption is that the user will configure this system-wide (or rather sink-wide) for all applications? Then applications should always offer any non-PCM formats that they support? > The current status is also that the user needs to explicitly switch to a > digital audio profile if the card also supports an analog profile. > Having a policy module to automatically select a profile to allow > matching non-PCM formats might make sense under some circumstances. -- Rémi Denis-Courmont http://www.remlab.net/
