ffmpegencoder: added range support to audio encoding

There isn't UI for this yet, but sending a time range to the encoder will now
encode just that range of audio.

app/codec/encoder.h

@@ -6,6 +6,7 @@
 
 #include "codec/frame.h"
 #include "common/constructors.h"
+#include "common/timerange.h"
 #include "render/audioparams.h"
 #include "render/videoparams.h"
 
@@ -82,7 +83,7 @@ public:
 public slots:
   void Open();
   void WriteFrame(FramePtr frame);
-  virtual void WriteAudio(const AudioRenderingParams& pcm_info, const QString& pcm_filename) = 0;
+  virtual void WriteAudio(const AudioRenderingParams& pcm_info, const QString& pcm_filename, const TimeRange &range) = 0;
   void Close();
 
 signals:

app/codec/ffmpeg/ffmpegencoder.cpp

@@ -17,7 +17,7 @@ FFmpegEncoder::FFmpegEncoder(const EncodingParams &params) :
 {
 }
 
-void FFmpegEncoder::WriteAudio(const AudioRenderingParams &pcm_info, const QString &pcm_filename)
+void FFmpegEncoder::WriteAudio(const AudioRenderingParams &pcm_info, const QString &pcm_filename, const TimeRange& range)
 {
   QFile pcm(pcm_filename);
   if (pcm.open(QFile::ReadOnly)) {
@@ -60,11 +60,25 @@ void FFmpegEncoder::WriteAudio(const AudioRenderingParams &pcm_info, const QStri
     av_frame_get_buffer(frame, 0);
     int sample_counter = 0;
 
-    while (!pcm.atEnd()) {
+    // Go to start range if one was set
+    if (range.in() > 0) {
+      pcm.seek(pcm_info.time_to_bytes(range.in()));
+    }
+
+    int end_in_bytes = pcm_info.time_to_bytes(range.out());
+
+    while (true) {
       int samples_needed = static_cast<int>(frame->nb_samples + swr_get_delay(swr_ctx, pcm_info.sample_rate()));
 
+      int max_read = pcm_info.samples_to_bytes(samples_needed);
+
+      // Limit read to end if necessary
+      if (pcm.pos() + max_read > end_in_bytes) {
+        max_read = end_in_bytes - pcm.pos();
+      }
+
       QByteArray input_data;
-      input_data = pcm.read(pcm_info.samples_to_bytes(samples_needed));
+      input_data = pcm.read(max_read);
       const char* input_data_array = input_data.constData();
       samples_needed = pcm_info.bytes_to_samples(input_data.size());
 
@@ -80,6 +94,10 @@ void FFmpegEncoder::WriteAudio(const AudioRenderingParams &pcm_info, const QStri
       sample_counter += converted;
 
       WriteAVFrame(frame, audio_codec_ctx_, audio_stream_);
+
+      if (pcm.atEnd() || pcm.pos() == end_in_bytes) {
+        break;
+      }
     }
 
     av_frame_free(&frame);

app/codec/ffmpeg/ffmpegencoder.h

@@ -17,7 +17,7 @@ public:
   FFmpegEncoder(const EncodingParams &params);
 
 public slots:
-  virtual void WriteAudio(const AudioRenderingParams& pcm_info, const QString& pcm_filename) override;
+  virtual void WriteAudio(const AudioRenderingParams& pcm_info, const QString& pcm_filename, const TimeRange &range) override;
 
 protected:
   virtual bool OpenInternal() override;

app/render/backend/exporter.cpp

@@ -22,6 +22,8 @@ Exporter::Exporter(ViewerOutput* viewer,
   connect(&debug_timer_, &QTimer::timeout, this, &Exporter::DebugTimerMessage);
 
   connect(this, &Exporter::ExportEnded, this, &Exporter::deleteLater);
+
+  export_range_ = TimeRange(0, viewer_node_->Length());
 }
 
 void Exporter::EnableVideo(const VideoRenderingParams &video_params, const QMatrix4x4 &transform, ColorProcessorPtr color_processor)
@@ -40,6 +42,11 @@ void Exporter::EnableAudio(const AudioRenderingParams &audio_params)
   audio_done_ = false;
 }
 
+void Exporter::OverrideExportRange(const TimeRange &range)
+{
+  export_range_ = range;
+}
+
 bool Exporter::GetExportStatus() const
 {
   return export_status_;
@@ -210,7 +217,8 @@ void Exporter::AudioRendered()
                             "WriteAudio",
                             Qt::QueuedConnection,
                             Q_ARG(const AudioRenderingParams&, audio_backend_->params()),
-                            Q_ARG(const QString&, cache_fn));
+                            Q_ARG(const QString&, cache_fn),
+                            Q_ARG(const TimeRange&, export_range_));
 
   // We don't need the audio backend anymore
   audio_backend_->deleteLater();

app/render/backend/exporter.h

@@ -23,6 +23,8 @@ public:
   void EnableVideo(const VideoRenderingParams& video_params, const QMatrix4x4& transform, ColorProcessorPtr color_processor);
   void EnableAudio(const AudioRenderingParams& audio_params);
 
+  void OverrideExportRange(const TimeRange& range);
+
   bool GetExportStatus() const;
   const QString& GetExportError() const;
 
@@ -57,6 +59,8 @@ protected:
 
   bool audio_done_;
 
+  TimeRange export_range_;
+
 private:
   void ExportSucceeded();