Make the frame timecodes consistent (#217)

* Make the frame timecodes consistent

* Remove unused import

* Use constant instead of 1M

* Avoid negative sleep values when ahead of schedule

Author: sirknightj

src/main/java/com/amazonaws/kinesisvideo/java/mediasource/file/ImageFileMediaSourceConfiguration.java

@@ -14,6 +14,7 @@ public class ImageFileMediaSourceConfiguration implements MediaSourceConfigurati
     private final int endFileIndex;
     private final String contentType;
     private final boolean allowStreamCreation;
+    private final long startTimeMs;
 
     public ImageFileMediaSourceConfiguration(final Builder builder) {
         this.fps = builder.fps;
@@ -23,6 +24,7 @@ public ImageFileMediaSourceConfiguration(final Builder builder) {
         this.endFileIndex = builder.endFileIndex;
         this.contentType = builder.contentType;
         this.allowStreamCreation = builder.allowStreamCreation;
+        this.startTimeMs = builder.startTimeMs;
     }
 
     public int getFps() {
@@ -49,6 +51,8 @@ public String getContentType() {
         return contentType;
     }
 
+    public long getStartTimeMs() { return startTimeMs; }
+
     @Override
     public String getMediaSourceType() {
         return null;
@@ -72,6 +76,7 @@ public static class Builder implements MediaSourceConfiguration.Builder<ImageFil
         private int endFileIndex;
         private String contentType = VIDEO_CONTENT_TYPE;
         private boolean allowStreamCreation;
+        private long startTimeMs = System.currentTimeMillis();
 
         public Builder fps(final int fps) {
             this.fps = fps;
@@ -111,6 +116,11 @@ public Builder allowStreamCreation(final Boolean allowStreamCreation) {
             return this;
         }
 
+        public Builder startTimeMs(final long startTimeMs) {
+            this.startTimeMs = startTimeMs;
+            return this;
+        }
+
         @Override
         public ImageFileMediaSourceConfiguration build() {
             return new ImageFileMediaSourceConfiguration(this);

src/main/java/com/amazonaws/kinesisvideo/java/mediasource/file/ImageFrameSource.java

@@ -21,6 +21,7 @@
 import static com.amazonaws.kinesisvideo.producer.FrameFlags.FRAME_FLAG_KEY_FRAME;
 import static com.amazonaws.kinesisvideo.producer.FrameFlags.FRAME_FLAG_NONE;
 import static com.amazonaws.kinesisvideo.producer.Time.HUNDREDS_OF_NANOS_IN_A_MILLISECOND;
+import static com.amazonaws.kinesisvideo.producer.Time.NANOS_IN_A_MILLISECOND;
 
 /**
  * Frame source backed by local image files.
@@ -40,11 +41,13 @@ public class ImageFrameSource {
     private final Log log = LogFactory.getLog(ImageFrameSource.class);
     private final String metadataName = "ImageLoop";
     private int metadataCount = 0;
+    private long currentFrameTimestampMs;
 
     public ImageFrameSource(final ImageFileMediaSourceConfiguration configuration) {
         this.configuration = configuration;
         this.totalFiles = getTotalFiles(configuration.getStartFileIndex(), configuration.getEndFileIndex());
         this.fps = configuration.getFps();
+        this.currentFrameTimestampMs = configuration.getStartTimeMs();
     }
 
     private int getTotalFiles(final int startIndex, final int endIndex) {
@@ -84,20 +87,29 @@ public void run() {
     }
 
     private void generateFrameAndNotifyListener() throws KinesisVideoException {
+        final double frameDurationMs = (double) Duration.ofSeconds(1L).toMillis() / fps;
+        long nextFrameTimeNs = System.nanoTime(); // to prevent time drift
+
         while (isRunning) {
             if (mkvDataAvailableCallback != null) {
-                mkvDataAvailableCallback.onFrameDataAvailable(createKinesisVideoFrameFromImage(frameCounter));
+                mkvDataAvailableCallback.onFrameDataAvailable(createKinesisVideoFrameFromImage(frameCounter, currentFrameTimestampMs));
                 if (isMetadataReady()) {
                     mkvDataAvailableCallback.onFragmentMetadataAvailable(metadataName + metadataCount,
                             Integer.toString(metadataCount++), false);
                 }
             }
 
             frameCounter++;
-            try {
-                Thread.sleep(Duration.ofSeconds(1L).toMillis() / fps);
-            } catch (final InterruptedException e) {
-                log.error("Frame interval wait interrupted by Exception ", e);
+            currentFrameTimestampMs = configuration.getStartTimeMs() + Math.round(frameCounter * frameDurationMs);
+            nextFrameTimeNs += (long)(frameDurationMs * NANOS_IN_A_MILLISECOND);
+
+            long sleepTimeMs = (nextFrameTimeNs - System.nanoTime()) / NANOS_IN_A_MILLISECOND; // Convert to Ms
+            if (sleepTimeMs > 0) {
+                try {
+                    Thread.sleep(sleepTimeMs);
+                } catch (final InterruptedException e) {
+                    log.error("Frame interval wait interrupted by Exception ", e);
+                }
             }
         }
     }
@@ -106,12 +118,11 @@ private boolean isMetadataReady() {
         return frameCounter % METADATA_INTERVAL == 0;
     }
 
-    private KinesisVideoFrame createKinesisVideoFrameFromImage(final long index) {
+    private KinesisVideoFrame createKinesisVideoFrameFromImage(final long index, final long timestampMs) {
         final String filename = String.format(
                 configuration.getFilenameFormat(),
                 index % totalFiles + configuration.getStartFileIndex());
         final Path path = Paths.get(configuration.getDir() + filename);
-        final long currentTimeMs = System.currentTimeMillis();
 
         final int flags = isKeyFrame() ? FRAME_FLAG_KEY_FRAME : FRAME_FLAG_NONE;
 
@@ -120,8 +131,8 @@ private KinesisVideoFrame createKinesisVideoFrameFromImage(final long index) {
             return new KinesisVideoFrame(
                     frameCounter,
                     flags,
-                    currentTimeMs * HUNDREDS_OF_NANOS_IN_A_MILLISECOND,
-                    currentTimeMs * HUNDREDS_OF_NANOS_IN_A_MILLISECOND,
+                    timestampMs * HUNDREDS_OF_NANOS_IN_A_MILLISECOND,
+                    timestampMs * HUNDREDS_OF_NANOS_IN_A_MILLISECOND,
                     FRAME_DURATION_20_MS * HUNDREDS_OF_NANOS_IN_A_MILLISECOND,
                     ByteBuffer.wrap(data));
         } catch (final IOException e) {

src/main/java/com/amazonaws/kinesisvideo/producer/Time.java

@@ -19,7 +19,7 @@ public class Time {
     public static final long HUNDREDS_OF_NANOS_IN_A_SECOND = 1000 * HUNDREDS_OF_NANOS_IN_A_MILLISECOND;
     public static final long HUNDREDS_OF_NANOS_IN_A_MINUTE = 60 * HUNDREDS_OF_NANOS_IN_A_SECOND;
     public static final long HUNDREDS_OF_NANOS_IN_AN_HOUR = 60 * HUNDREDS_OF_NANOS_IN_A_MINUTE;
-    public static final long NANOS_IN_A_MILLISECOND = 1000000;
+    public static final long NANOS_IN_A_MILLISECOND = 1_000_000;
 
     /**
      * Gets the current time in producer time units