/* Copyright 2016, Ableton AG, Berlin. All rights reserved.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*
* If you would like to incorporate Link into a proprietary software application,
* please contact .
*/
#pragma once
#include
#include
namespace ableton
{
namespace link
{
// Clamp the tempo of the given timeline to the valid Link range
inline Timeline clampTempo(const Timeline timeline)
{
const double kMinBpm = 20.0;
const double kMaxBpm = 999.0;
return {Tempo{(std::min)((std::max)(timeline.tempo.bpm(), kMinBpm), kMaxBpm)},
timeline.beatOrigin, timeline.timeOrigin};
}
// Given an existing client timeline, a session timeline, and the
// global host transform of the session, return a new version of the client
// timeline. The resulting new client timeline is continuous with the
// previous timeline so that curClient.toBeats(atTime) ==
// result.toBeats(atTime).
inline Timeline updateClientTimelineFromSession(const Timeline curClient,
const Timeline session,
const std::chrono::microseconds atTime,
const GhostXForm xform)
{
// An intermediate timeline representing the continuation of the
// existing client timeline with the tempo from the session timeline.
const auto tempTl = Timeline{session.tempo, curClient.toBeats(atTime), atTime};
// The host time corresponding to beat 0 on the session
// timeline. Beat 0 on the session timeline is important because it
// serves as the origin of the quantization grid for all participants.
const auto hostBeatZero = xform.ghostToHost(session.fromBeats(Beats{INT64_C(0)}));
// The new client timeline becomes the result of sliding the
// intermediate timeline back so that it's anchor corresponds to
// beat zero on the session timeline. The result preserves the
// magnitude of beats on the client timeline while encoding the
// quantization reference point in the time and beatOrigins.
return {tempTl.tempo, tempTl.toBeats(hostBeatZero), hostBeatZero};
}
inline Timeline updateSessionTimelineFromClient(const Timeline curSession,
const Timeline client,
const std::chrono::microseconds atTime,
const GhostXForm xform)
{
// The client timeline was constructed so that it's timeOrigin
// corresponds to beat 0 on the session timeline.
const auto ghostBeat0 = xform.hostToGhost(client.timeOrigin);
const auto zero = Beats{INT64_C(0)};
// If beat 0 was not shifted and there is not a new tempo, an update
// of the session timeline is not required. Don't create an
// equivalent timeline with different anchor points if not needed as
// this will trigger other unnecessary changes.
if (curSession.toBeats(ghostBeat0) == zero && client.tempo == curSession.tempo)
{
return curSession;
}
else
{
// An intermediate timeline representing the new tempo, the
// effective time, and a possibly adjusted origin.
const auto tempTl = Timeline{client.tempo, zero, ghostBeat0};
// The final session timeline must have the beat corresponding to
// atTime on the old session timeline as its beatOrigin because this is
// used for prioritization of timelines among peers - we can't let a
// modification applied by the client artificially increase or
// reduce the timeline's priority in the session. The new beat
// origin should be as close as possible to lining up with atTime,
// but we must also make sure that it's > curSession.beatOrigin
// because otherwise it will get ignored.
const auto newBeatOrigin = (std::max)(curSession.toBeats(xform.hostToGhost(atTime)),
curSession.beatOrigin + Beats{INT64_C(1)});
return {client.tempo, newBeatOrigin, tempTl.fromBeats(newBeatOrigin)};
}
}
// Shift timeline so result.toBeats(t) == client.toBeats(t) +
// shift. This takes into account the fact that the timeOrigin
// corresponds to beat 0 on the session timeline. Using this function
// and then setting the session timeline with the result will change
// the phase of the session by the given shift amount.
inline Timeline shiftClientTimeline(Timeline client, const Beats shift)
{
const auto timeDelta = client.fromBeats(shift) - client.fromBeats(Beats{INT64_C(0)});
client.timeOrigin = client.timeOrigin - timeDelta;
return client;
}
} // namespace link
} // namespace ableton