This hopefully fixes an issue with port-registration (new session)
being skipped because PortAudioBackend::available() still false
until the first callback.
This issue is not always reproducible but when it does occur it happens
somewhat consistently on both 32bit and 64bit builds(Tested on Windows 7).
The midiOutReset call does not return (or it takes so long that it might as
well be indefinite) and as it is not strictly necessary just remove it.
Resolves: http://tracker.ardour.org/view.php?id=7095
uselib is no longer implicit (inherited by .use). This is still incomplete,
some uselibs for non-linux variants may be missing.
bld.is_defined("HAVE_XXX") also no longer works and will have to be
changed (I think to bld.env["HAVE_XXX"]) in countless places.
For drivers that correctly report latency values(ASIO) this should result a
much closer alignment of audio in a loopback test. Measurement and
adjustment may still be needed, especially for non-ASIO drivers.
Testing with the RME HDSP Multiface and Yamaha AG06 using ASIO drivers results
in maximum offset of a couple of samples.
This has been tested on four devices:
- A RME HDSP Multiface
- A Yamaha AG06
- A Focusrite 2i2
- A built-in soundcard running ASIO4ALL
The HDSP and the AG06 only return one buffer size when queried so the preferred
size is used as before.
The Focusrite returns a min corresponding to the position of the slider in the
control dialog and the max is 1024. The granularity is 1 so this means that the
number of values needs to be reduced for the current UI design with a combo
box so the granularity is increased until there are around 8-9 buffer sizes to
choose from evenly spaced between min and max(but we could easily change this
if the UI changes etc).
The ASIO4ALL driver returns a min of 64 and a max of 2048 and a granularity of
8. So where the minimum buffer size and granularity is a power of 2 use only
buffer sizes that are power of 2.
If the driver returns different values for min and max it is not currently
possible to indicate which is the driver preferred value. A checkbox or other
UI element could be added to the AudioSetup dialog to only use the preferred
value but that is more work and perhaps not necessary.
midiInReset triggers the sysex callback to tell the application that it has
finished with the buffer. Calling midiInAddBuffer results in an infinite loop
so just return during shutdown.
Having error codes defined in PortaudioIO means it is not dependent on the
ErrorCodes in AudioBackend but it doesn't really make sense to have another
set, so just use the PA ones until they become insufficient.
Add functions for get/set the Multimedia timer resolution, although we are
really only interested in the minimum, this will facilitate testing
Put timer utility functions inside nested namespaces as they are platform
specific
