[cscore] Use frame time in Linux UsbCameraImpl (#7609)

wpiutil/src/main/java/edu/wpi/first/util/RawFrame.java

@@ -18,6 +18,8 @@ public class RawFrame implements AutoCloseable {
   private int m_height;
   private int m_stride;
   private PixelFormat m_pixelFormat = PixelFormat.kUnknown;
+  private long m_time;
+  private TimestampSource m_timeSource = TimestampSource.kUnknown;
 
   /** Construct a new empty RawFrame. */
   public RawFrame() {
@@ -43,12 +45,15 @@ public class RawFrame implements AutoCloseable {
    * @param stride The number of bytes in each row of image data
    * @param pixelFormat The PixelFormat of the frame
    */
-  void setDataJNI(ByteBuffer data, int width, int height, int stride, int pixelFormat) {
+  void setDataJNI(
+      ByteBuffer data, int width, int height, int stride, int pixelFormat, long time, int timeSrc) {
     m_data = data;
     m_width = width;
     m_height = height;
     m_stride = stride;
     m_pixelFormat = PixelFormat.getFromInt(pixelFormat);
+    m_time = time;
+    m_timeSource = TimestampSource.getFromInt(timeSrc);
   }
 
   /**
@@ -59,11 +64,13 @@ public class RawFrame implements AutoCloseable {
    * @param stride The number of bytes in each row of image data
    * @param pixelFormat The PixelFormat of the frame
    */
-  void setInfoJNI(int width, int height, int stride, int pixelFormat) {
+  void setInfoJNI(int width, int height, int stride, int pixelFormat, long time, int timeSrc) {
     m_width = width;
     m_height = height;
     m_stride = stride;
     m_pixelFormat = PixelFormat.getFromInt(pixelFormat);
+    m_time = time;
+    m_timeSource = TimestampSource.getFromInt(timeSrc);
   }
 
   /**
@@ -110,6 +117,19 @@ public class RawFrame implements AutoCloseable {
         pixelFormat.getValue());
   }
 
+  /**
+   * Update this frame's timestamp info.
+   *
+   * @param frameTime the time this frame was grabbed at. This uses the same time base as
+   *     wpi::Now(), in us.
+   * @param frameTimeSource the time source for the timestamp this frame was grabbed at.
+   */
+  public void setTimeInfo(long frameTime, TimestampSource frameTimeSource) {
+    m_time = frameTime;
+    m_timeSource = frameTimeSource;
+    WPIUtilJNI.setRawFrameTime(m_nativeObj, frameTime, frameTimeSource.getValue());
+  }
+
   /**
    * Get the pointer to native representation of this frame.
    *
@@ -185,4 +205,22 @@ public class RawFrame implements AutoCloseable {
   public PixelFormat getPixelFormat() {
     return m_pixelFormat;
   }
+
+  /**
+   * Get the time this frame was grabbed at. This uses the same time base as wpi::Now(), in us.
+   *
+   * @return Time in 1 us increments.
+   */
+  public long getTimestamp() {
+    return m_time;
+  }
+
+  /**
+   * Get the time source for the timestamp this frame was grabbed at.
+   *
+   * @return Time source
+   */
+  public TimestampSource getTimestampSource() {
+    return m_timeSource;
+  }
 }

wpiutil/src/main/java/edu/wpi/first/util/TimestampSource.java

@@ -0,0 +1,51 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.util;
+
+/**
+ * Options for where the timestamp an {@link RawFrame} was captured at can be measured relative to.
+ */
+public enum TimestampSource {
+  /** unknown. */
+  kUnknown(0),
+  /**
+   * wpi::Now when the new frame was dequeued by CSCore. Does not account for camera exposure time
+   * or V4L latency.
+   */
+  kFrameDequeue(1),
+  /** End of Frame. Same as V4L2_BUF_FLAG_TSTAMP_SRC_EOF, translated into wpi::Now's timebase. */
+  kV4LEOF(2),
+  /**
+   * Start of Exposure. Same as V4L2_BUF_FLAG_TSTAMP_SRC_SOE, translated into wpi::Now's timebase.
+   */
+  kV4LSOE(3);
+
+  private final int value;
+
+  TimestampSource(int value) {
+    this.value = value;
+  }
+
+  /**
+   * Gets the integer value of the pixel format.
+   *
+   * @return Integer value
+   */
+  public int getValue() {
+    return value;
+  }
+
+  private static final TimestampSource[] s_values = values();
+
+  /**
+   * Gets a TimestampSource enum value from its integer value.
+   *
+   * @param timestampSource integer value
+   * @return Enum value
+   */
+  public static TimestampSource getFromInt(int timestampSource) {
+    return s_values[timestampSource];
+  }
+}

wpiutil/src/main/java/edu/wpi/first/util/WPIUtilJNI.java

@@ -175,6 +175,8 @@ public class WPIUtilJNI {
   static native void setRawFrameInfo(
       long frame, int size, int width, int height, int stride, int pixelFormat);
 
+  static native void setRawFrameTime(long frame, long timestamp, int timeSource);
+
   /**
    * Waits for a handle to be signaled.
    *