The general goal is to align transport-sample to be the audible frame
and use that as "anchor" for all processing.
transport_sample cannot become negative (00:00:00:00 is the first audible
frame).
Internally transport pre-rolls (read-ahead) before the transport starts
to move. This allows inputs and disk to prefill the pipeline.
When starting to roll, the session counts down a global "remaning preroll"
counter, which is the worst-latency from in-to-out.
Each route in turn will start processing at its own output-latency.
Route::process_output_buffers() - which does the actual processing
incl disk i/o - begins by offsetting the "current sample" by the
route's process-latency and decrements the offset for each latent
processor. At the end of the function the output will be aligned
and match transport-sample - downstream-playback-latency (if any).
PS. This commit is a first step only: transport looping & vari-speed have
not yet been implemented/updated.
This is mostly to see if there'll be any problems when merging these changes into Mixbus. I'm guessing there'll be some conflicts in these projects (and a lot more to follow...)
After over 17 years of honorable service to the Ardour Codebase.
ClickBox and AutoSpin are retiring into the git nirvana.
We're glad for the duty, decency, reliability, dignity, respect which
these classes brought to Arodur and look back in gratitude on their years
of service.
PS. First one to say "cruft" will be fired.
Currently, the scroll handler obeys to the page increment, but instead
of using the step increment for more precise scroll, it uses an
hardcoded one tenth of the page increment.
Use the step increment instead since it has been filled with sensible
values by ArdourFader's users.
smallstep (resp. largestep) is intended to be the interface delta
corresponding to a desc.smallstep (resp. largestep) in internal scale,
and is computed by incrementing from desc.lower.
But ac->internal_to_interface(desc.lower) isn't necessarily zero. In
fact it currently is 0.5 / (M - m + 1) for integer parameters where M is
the maximum and m is the minimum possible value since it is the center
of the [0,1/(M-m+1)] interval.
Since the lower bound of the delta isn't always zero, don't ignore it
when computing the actual increment.
This fixes various issues with integer controls (some values are not
reachable due to incorrect rounding in AutoSpin) and also pulls
in the various benefits of BarController:
* mouse-drags
* numeric entry
* alternative entry modes (piano-keyboard, tempo-based values)
If this style remains, ClickBox & AutoSpin should be removed from
the codebase.
Removing a Track does not delete its playlists and one can keep
Playlists after Cleanup. Don't crash if a the track that the playlist
originally belonged to does no longer exist.
Set accumulated capture-latency for physical-outputs
and accumulated playback-latency for physical-inputs
after Ardour is done setting all non-physical port latencies.
This will be needed for latency-compensation of the complete graph.
Session::post_playback_latency() sets the actual route latency,
so that playback latency notifications need to come after capture-
latency (backends follow the same rule: capture first).
NB. Session::initialize_latencies() was already using the correct order
If disk-monitoring is disabled: disk-reader position is not relevant.
If Rec-arm is off: disk-writer position is not relevant.
But...
Play -> [plugins] -> Record
is basically a bounce and best done using the bounce operation.
(faster than realtime).
Input + Play -> Record -> Output
Ardour would need to align playback with the Input to be recorded
and at the same time align it with output, so that a player can play
along on the same track. That's not possible without a time-machine (or
a 2nd play processor).
While it can work in theory under some special circumstances, allowing
the disk-reader before the disk-writer is really just confusing,
error prone and valid uses cases are better handled by dedicated
operations.
