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Bug 1947 - Clicky play when dynamically changing number of playing channels

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Rather than 'cut' (i.e. drop, not cut as in 'cut preview') channels immediately, we now only do so
if their last gain was already 0.0.  Instead they micro-fade out.  Later when the channels come back,
their last gain will be 0.0, so they will micro-fade in.

A comment explains that the code would be cleaner if we just computed gains, and not whether to
drop channels.
This commit is contained in:
James Crook 2018-08-25 12:41:16 +01:00
parent f296f42392
commit b91300caf0
3 changed files with 46 additions and 9 deletions
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50
src/AudioIO.cpp
View File

@ -4985,7 +4985,20 @@ int AudioIO::AudioCallback(const void *inputBuffer, void *outputBuffer,
if( outputBuffer && (numPlaybackChannels > 0) )
{
// The cut and cutQuickly booleans are for historical reasons.
// JKC: The original code attempted to be faster by doing nothing on silenced audio.
// This, IMHO, is 'premature optimisation'. Instead clearer and cleaner code would
// simply use a gain of 0.0 for silent audio and go on through to the stage of
// applying that 0.0 gain to the data mixed into the buffer.
// Then (and only then) we would have if needed fast paths for:
// - Applying a uniform gain of 0.0.
// - Applying a uniform gain of 1.0.
// - Applying some other uniform gain.
// - Applying a linearly interpolated gain.
// I would expect us not to need the fast paths, since linearly interpolated gain
// is very cheap to process.
bool cut = false;
bool cutQuickly = false;
bool linkFlag = false;
float *outputFloats = (float *)outputBuffer;
@ -5045,10 +5058,16 @@ int AudioIO::AudioCallback(const void *inputBuffer, void *outputBuffer,
chans[chanCnt] = vt;
if (linkFlag)
if (linkFlag) {
linkFlag = false;
if (vt->GetChannelIgnoringPan() == Track::LeftChannel)
cutQuickly = cutQuickly && (vt->GetOldChannelGain(0) == 0.0);
if (vt->GetChannelIgnoringPan() == Track::RightChannel )
cutQuickly = cutQuickly && (vt->GetOldChannelGain(1) == 0.0);
}
else {
cut = false;
cutQuickly = false;
// Cut if somebody else is soloing
if (numSolo>0 && !vt->GetSolo())
@ -5066,13 +5085,22 @@ int AudioIO::AudioCallback(const void *inputBuffer, void *outputBuffer,
{
memset(tempBufs[1], 0, framesPerBuffer * sizeof(float));
}
cutQuickly = cut;
if (vt->GetChannelIgnoringPan() == Track::LeftChannel ||
vt->GetChannelIgnoringPan() == Track::MonoChannel )
cutQuickly = cutQuickly && (vt->GetOldChannelGain(0) == 0.0);
if (vt->GetChannelIgnoringPan() == Track::RightChannel ||
vt->GetChannelIgnoringPan() == Track::MonoChannel )
cutQuickly = cutQuickly && (vt->GetOldChannelGain(1) == 0.0);
}
#define ORIGINAL_DO_NOT_PLAY_ALL_MUTED_TRACKS_TO_END
#ifdef ORIGINAL_DO_NOT_PLAY_ALL_MUTED_TRACKS_TO_END
decltype(framesPerBuffer) len = 0;
// this is original code prior to r10680 -RBD
if (cut)
if (cutQuickly)
{
len = mPlaybackBuffers[t]->Discard(framesPerBuffer);
// keep going here.
@ -5112,7 +5140,7 @@ int AudioIO::AudioCallback(const void *inputBuffer, void *outputBuffer,
// playback that might also be going on? ...Maybe muted audio tracks + MIDI,
// the playback would NEVER terminate. ...I think the #else part is probably preferable...
size_t len;
if (cut)
if (cutQuickly)
{
len =
mPlaybackBuffers[t]->Discard(framesPerBuffer);
@ -5128,7 +5156,7 @@ int AudioIO::AudioCallback(const void *inputBuffer, void *outputBuffer,
// Last channel seen now
len = maxLen;
if( !cut && selected )
if( !cutQuickly && selected )
{
len = em.RealtimeProcess(group, chanCnt, tempBufs, len);
}
@ -5137,17 +5165,19 @@ int AudioIO::AudioCallback(const void *inputBuffer, void *outputBuffer,
CallbackCheckCompletion(callbackReturn, len);
if (cut) // no samples to process, they've been discarded
if (cutQuickly) // no samples to process, they've been discarded
continue;
if (len > 0) for (int c = 0; c < chanCnt; c++)
{
vt = chans[c];
if (vt->GetChannel() == Track::LeftChannel ||
vt->GetChannel() == Track::MonoChannel)
if (vt->GetChannelIgnoringPan() == Track::LeftChannel ||
vt->GetChannelIgnoringPan() == Track::MonoChannel )
{
float gain = vt->GetChannelGain(0);
if (cut)
gain = 0.0;
// Output volume emulation: possibly copy meter samples, then
// apply volume, then copy to the output buffer
@ -5169,10 +5199,12 @@ int AudioIO::AudioCallback(const void *inputBuffer, void *outputBuffer,
}
if (vt->GetChannel() == Track::RightChannel ||
vt->GetChannel() == Track::MonoChannel)
if (vt->GetChannelIgnoringPan() == Track::RightChannel ||
vt->GetChannelIgnoringPan() == Track::MonoChannel )
{
float gain = vt->GetChannelGain(1);
if (cut)
gain = 0.0;
// Output volume emulation (as above)
if (outputMeterFloats != outputFloats)

4
src/WaveTrack.cpp
View File

@ -237,6 +237,10 @@ void WaveTrack::SetOffset(double o)
mOffset = o;
}
int WaveTrack::GetChannelIgnoringPan() const {
return mChannel;
}
int WaveTrack::GetChannel() const
{
if( mChannel != Track::MonoChannel )

1
src/WaveTrack.h
View File

@ -98,6 +98,7 @@ private:
double GetOffset() const override;
void SetOffset(double o) override;
virtual int GetChannelIgnoringPan() const;
virtual int GetChannel() const override;
virtual void SetPanFromChannelType() override;