began node hashing for improved cache

app/decoder/decoder.h

@@ -160,6 +160,13 @@ public:
    */
   virtual void Close() = 0;
 
+  /**
+   * @brief Get a media file's internal timestamp
+   *
+   * Used to determine which frame will be served at a given time, useful for caching.
+   */
+  virtual int64_t GetTimestampFromTime(const rational& time) = 0;
+
   /**
    * @brief Try to probe a Footage file by passing it through all available Decoders
    *

app/decoder/ffmpeg/ffmpegdecoder.cpp

@@ -195,10 +195,7 @@ FramePtr FFmpegDecoder::Retrieve(const rational &timecode, const rational &lengt
   }
 
   // Convert timecode to AVStream timebase
-  int64_t target_ts = qFloor(timecode.toDouble() * rational(avstream_->time_base).flipped().toDouble());
-
-  // Find closest actual timebase in the file
-  target_ts = GetClosestTimestampInIndex(target_ts);
+  int64_t target_ts = GetTimestampFromTime(timecode);
 
   if (target_ts < 0) {
     Error(tr("Index failed to produce a valid timestamp"));
@@ -323,6 +320,21 @@ QString FFmpegDecoder::id()
   return "ffmpeg";
 }
 
+int64_t FFmpegDecoder::GetTimestampFromTime(const rational &time)
+{
+  if (!open_ && !Open()) {
+    return -1;
+  }
+
+  // Convert timecode to AVStream timebase
+  int64_t target_ts = qFloor(time.toDouble() * rational(avstream_->time_base).flipped().toDouble());
+
+  // Find closest actual timebase in the file
+  target_ts = GetClosestTimestampInIndex(target_ts);
+
+  return target_ts;
+}
+
 bool FFmpegDecoder::Probe(Footage *f)
 {
   if (open_) {

app/decoder/ffmpeg/ffmpegdecoder.h

@@ -51,6 +51,8 @@ public:
 
   virtual QString id() override;
 
+  virtual int64_t GetTimestampFromTime(const rational& time) override;
+
 private:
   /**
    * @brief Handle an error
@@ -117,6 +119,8 @@ private:
    */
   void SaveFrameIndex();
 
+  int64_t GetClosestTimestampInIndex(const int64_t& ts);
+
   /**
    * @brief Returns an AVPixelFormat that can be
    * @param pix_fmt
@@ -124,8 +128,6 @@ private:
    */
   AVPixelFormat GetCompatiblePixelFormat(const AVPixelFormat& pix_fmt);
 
-  int64_t GetClosestTimestampInIndex(const int64_t& ts);
-
   AVFormatContext* fmt_ctx_;
   AVCodecContext* codec_ctx_;
   AVStream* avstream_;