'Twas brillig, and David Henningsson at 10/10/10 09:19 did gyre and gimble: > On 2010-10-09 20:27, Arun Raghavan wrote: >> and this would make that >> considerably simpler (and more fruitful, since we'd have to jump >> through hoops >> to deal with volumes>= 2^31 while doing signed multiplication). If we >> choose >> to retain the old hand-optimised assembly, that should also benefit >> from this >> change. > > I'm not exactly sure where and for what PA_VOLUME_MAX is used, but does > it correspond to 0 dB in any way? Thinking assembly, could it be that we > have some e g fixed-point arithmetic that we must compensate? No, PA_VOLUME_NORM represents 0dB (or rather *our* 0dB as the alsa 0dB point is represented by Base Volume (which varies from h/w to h/w). I can't really think of any implementation that genuinely uses PA_VOLUME_MAX, so I think considering this value to be internal is safe enough even if it is technically exposed via public headers (in other words it *shouldn't* be changed, but for all practical uses, it can be). I'd also like to expose a new constant in the headers called PA_VOLUME_OVERDRIVE (or similarly named) that represents +11dB and should be our generally recommended "overdrive" (aka software amplification > 100%) amount for volume control UIs. Currently gnome-volume-control allows up to PA_VOLUME_NORM*1.5 which is ~= +11dB via current mappings, which is one reason why we previously decided on +11dB as our overdrive amount. That said, other volume control UIs (pavucontrol, kmix and, surprisingly, gnome-volume-control-applet) only allow volumes up to PA_VOLUME_NORM, so the idea would be to allow them to go right up to PA_VOLUME_OVERDRIVE, and hopefully implement an appropriate use of colours and markers etc. to make it clear to the user that they may not want to go >100% or risk clipping. http://pulseaudio.org/wiki/WritingVolumeControlUIs#Colouredvolumesliders Col -- Colin Guthrie gmane(at)colin.guthr.ie http://colin.guthr.ie/ Day Job: Tribalogic Limited [http://www.tribalogic.net/] Open Source: Mageia Contributor [http://www.mageia.org/] PulseAudio Hacker [http://www.pulseaudio.org/] Trac Hacker [http://trac.edgewall.org/]
