renderer: generate audio waveforms in render threads

Solves UI lag issues with long audio sequences.

app/render/audioplaybackcache.cpp

@@ -48,6 +48,7 @@ void AudioPlaybackCache::SetParameters(const AudioParams &params)
   }
 
   params_ = params;
+  visual_.set_channel_count(params_.channel_count());
 
   // Restart empty file so there's always "something" to play
   ClearPlaylist();
@@ -55,7 +56,7 @@ void AudioPlaybackCache::SetParameters(const AudioParams &params)
   emit ParametersChanged();
 }
 
-void AudioPlaybackCache::WritePCM(const TimeRange &range, SampleBufferPtr samples, const qint64 &job_time)
+void AudioPlaybackCache::WritePCM(const TimeRange &range, SampleBufferPtr samples, const AudioVisualWaveform *waveform, const qint64 &job_time)
 {
   QList<TimeRange> valid_ranges = GetValidRanges(range, job_time);
   if (valid_ranges.isEmpty()) {
@@ -83,6 +84,7 @@ void AudioPlaybackCache::WritePCM(const TimeRange &range, SampleBufferPtr sample
   foreach (const TimeRange& r, valid_ranges) {
     rational this_segment_in = 0;
 
+    // Write PCM to playlist
     for (auto it=playlist_.begin(); it!=playlist_.end(); it++) {
       rational this_segment_out = this_segment_in + params_.bytes_to_time((*it).size());
 
@@ -138,6 +140,13 @@ void AudioPlaybackCache::WritePCM(const TimeRange &range, SampleBufferPtr sample
       // Each segment is contiguous, so this out will be the next segment's in
       this_segment_in = this_segment_out;
     }
+
+    // Write visual
+    if (waveform) {
+      visual_.OverwriteSums(*waveform, r.in(), r.in() - range.in(), r.length());
+    } else {
+      visual_.OverwriteSilence(r.in(), r.length());
+    }
   }
 
   foreach (const TimeRange& v, ranges_we_validated) {
@@ -149,7 +158,7 @@ void AudioPlaybackCache::WriteSilence(const TimeRange &range, qint64 job_time)
 {
   // WritePCM will automatically fill non-existent bytes with silence, so we just have to send
   // it an empty sample buffer
-  WritePCM(range, nullptr, job_time);
+  WritePCM(range, nullptr, nullptr, job_time);
 }
 
 void AudioPlaybackCache::ShiftEvent(const rational &from_in_time, const rational &to_in_time)

app/render/audioplaybackcache.h

@@ -21,6 +21,7 @@
 #ifndef AUDIOPLAYBACKCACHE_H
 #define AUDIOPLAYBACKCACHE_H
 
+#include "audio/audiovisualwaveform.h"
 #include "common/timerange.h"
 #include "codec/samplebuffer.h"
 #include "render/playbackcache.h"
@@ -65,7 +66,7 @@ public:
 
   void SetParameters(const AudioParams& params);
 
-  void WritePCM(const TimeRange &range, SampleBufferPtr samples, const qint64& job_time);
+  void WritePCM(const TimeRange &range, SampleBufferPtr samples, const AudioVisualWaveform *waveform, const qint64& job_time);
 
   void WriteSilence(const TimeRange &range, qint64 job_time);
 
@@ -181,6 +182,11 @@ public:
    */
   PlaybackDevice* CreatePlaybackDevice(QObject *parent = nullptr) const;
 
+  const AudioVisualWaveform &visual() const
+  {
+    return visual_;
+  }
+
 signals:
   void ParametersChanged();
 
@@ -212,6 +218,8 @@ private:
 
   AudioParams params_;
 
+  AudioVisualWaveform visual_;
+
 };
 
 }

app/render/previewautocacher.cpp

@@ -171,8 +171,11 @@ void PreviewAutoCacher::AudioRendered()
     if (watcher->HasResult()) {
       const TimeRange &range = audio_tasks_.value(watcher);
 
+      AudioVisualWaveform waveform = watcher->GetTicket()->property("waveform").value<AudioVisualWaveform>();
+
       viewer_node_->audio_playback_cache()->WritePCM(range,
                                                      watcher->Get().value<SampleBufferPtr>(),
+                                                     &waveform,
                                                      watcher->GetTicket()->GetJobTime());
 
       bool pcm_is_usable = true;
@@ -506,7 +509,7 @@ void PreviewAutoCacher::TryRender()
 
   if (!invalidated_audio_.isEmpty()) {
     foreach (const TimeRange& range, invalidated_audio_) {
-      std::list<TimeRange> chunks = range.Split(2);
+      std::list<TimeRange> chunks = range.Split(30);
 
       foreach (const TimeRange& r, chunks) {
         RenderTicketWatcher* watcher = new RenderTicketWatcher();

app/render/renderprocessor.cpp

@@ -173,7 +173,16 @@ void RenderProcessor::Run()
       table = GenerateTable(texture_output.node(), texture_output.output(), time);
     }
 
-    ticket_->Finish(table.Get(NodeValue::kSamples));
+    QVariant sample_variant = table.Get(NodeValue::kSamples);
+    SampleBufferPtr samples = sample_variant.value<SampleBufferPtr>();
+    if (samples && ticket_->property("enablewaveforms").toBool()) {
+      AudioVisualWaveform vis;
+      vis.set_channel_count(samples->audio_params().channel_count());
+      vis.OverwriteSamples(samples, samples->audio_params().sample_rate());
+      ticket_->setProperty("waveform", QVariant::fromValue(vis));
+    }
+
+    ticket_->Finish(sample_variant);
     break;
   }
   case RenderManager::kTypeVideoDownload: