HDR: Add COLOR_TRANSFER_LINEAR in C.java.

This is more clear than using Format.NO_VALUE, when we do actually intend for an
output value.

Also, fix @see formatting by using summary fragments instead, and add an error
output for OETF and EOTF transfer functions.

PiperOrigin-RevId: 490910229

library/common/src/main/java/com/google/android/exoplayer2/C.java

@@ -1048,24 +1048,27 @@ public final class C {
   // LINT.IfChange(color_transfer)
   /**
    * Video color transfer characteristics. One of {@link Format#NO_VALUE}, {@link
-   * #COLOR_TRANSFER_SDR}, {@link #COLOR_TRANSFER_ST2084} or {@link #COLOR_TRANSFER_HLG}.
+   * #COLOR_TRANSFER_LINEAR}, {@link #COLOR_TRANSFER_SDR}, {@link #COLOR_TRANSFER_ST2084} or {@link
+   * #COLOR_TRANSFER_HLG}.
    */
   @Documented
   @Retention(RetentionPolicy.SOURCE)
   @Target(TYPE_USE)
-  @IntDef({Format.NO_VALUE, COLOR_TRANSFER_SDR, COLOR_TRANSFER_ST2084, COLOR_TRANSFER_HLG})
+  @IntDef({
+    Format.NO_VALUE,
+    COLOR_TRANSFER_LINEAR,
+    COLOR_TRANSFER_SDR,
+    COLOR_TRANSFER_ST2084,
+    COLOR_TRANSFER_HLG
+  })
   public @interface ColorTransfer {}
-  /**
-   * @see MediaFormat#COLOR_TRANSFER_SDR_VIDEO
-   */
+  /** See {@link MediaFormat#COLOR_TRANSFER_LINEAR}. */
+  public static final int COLOR_TRANSFER_LINEAR = MediaFormat.COLOR_TRANSFER_LINEAR;
+  /** See {@link MediaFormat#COLOR_TRANSFER_SDR_VIDEO}. */
   public static final int COLOR_TRANSFER_SDR = MediaFormat.COLOR_TRANSFER_SDR_VIDEO;
-  /**
-   * @see MediaFormat#COLOR_TRANSFER_ST2084
-   */
+  /** See {@link MediaFormat#COLOR_TRANSFER_ST2084}. */
   public static final int COLOR_TRANSFER_ST2084 = MediaFormat.COLOR_TRANSFER_ST2084;
-  /**
-   * @see MediaFormat#COLOR_TRANSFER_HLG
-   */
+  /** See {@link MediaFormat#COLOR_TRANSFER_HLG}. */
   public static final int COLOR_TRANSFER_HLG = MediaFormat.COLOR_TRANSFER_HLG;
 
   // LINT.IfChange(color_range)

library/common/src/main/java/com/google/android/exoplayer2/util/MediaFormatUtil.java

@@ -321,7 +321,8 @@ public final class MediaFormatUtil {
   /** Whether this is a valid {@link C.ColorTransfer} instance. */
   private static boolean isValidColorTransfer(int colorTransfer) {
     // LINT.IfChange(color_transfer)
-    return colorTransfer == C.COLOR_TRANSFER_SDR
+    return colorTransfer == C.COLOR_TRANSFER_LINEAR
+        || colorTransfer == C.COLOR_TRANSFER_SDR
         || colorTransfer == C.COLOR_TRANSFER_ST2084
         || colorTransfer == C.COLOR_TRANSFER_HLG
         || colorTransfer == Format.NO_VALUE;

library/common/src/main/java/com/google/android/exoplayer2/video/ColorInfo.java

@@ -90,11 +90,16 @@ public final class ColorInfo implements Bundleable {
     }
   }
 
-  /** Returns whether the {@code ColorInfo} uses an HDR {@link C.ColorTransfer}. */
+  /**
+   * Returns whether the {@code ColorInfo} uses an HDR {@link C.ColorTransfer}.
+   *
+   * <p>{@link C#COLOR_TRANSFER_LINEAR} is not considered to be an HDR {@link C.ColorTransfer},
+   * because it may represent either SDR or HDR contents.
+   */
   public static boolean isTransferHdr(@Nullable ColorInfo colorInfo) {
     return colorInfo != null
-        && colorInfo.colorTransfer != Format.NO_VALUE
-        && colorInfo.colorTransfer != C.COLOR_TRANSFER_SDR;
+        && (colorInfo.colorTransfer == C.COLOR_TRANSFER_HLG
+            || colorInfo.colorTransfer == C.COLOR_TRANSFER_ST2084);
   }
 
   /**
@@ -110,9 +115,9 @@ public final class ColorInfo implements Bundleable {
   public final @C.ColorRange int colorRange;
 
   /**
-   * The color transfer characteristics of the video. Valid values are {@link C#COLOR_TRANSFER_HLG},
-   * {@link C#COLOR_TRANSFER_ST2084}, {@link C#COLOR_TRANSFER_SDR} or {@link Format#NO_VALUE} if
-   * unknown.
+   * The color transfer characteristics of the video. Valid values are {@link
+   * C#COLOR_TRANSFER_LINEAR}, {@link C#COLOR_TRANSFER_HLG}, {@link C#COLOR_TRANSFER_ST2084}, {@link
+   * C#COLOR_TRANSFER_SDR} or {@link Format#NO_VALUE} if unknown.
    */
   public final @C.ColorTransfer int colorTransfer;
 

library/effect/src/main/assets/shaders/fragment_shader_oetf_es3.glsl

@@ -79,12 +79,20 @@ highp vec3 pqOetf(highp vec3 linearColor) {
 highp vec3 getElectricalColor(highp vec3 linearColor) {
   // LINT.IfChange(color_transfer)
   const int COLOR_TRANSFER_ST2084 = 6;
-  return (uOetfColorTransfer == COLOR_TRANSFER_ST2084) ?
-      pqOetf(linearColor) : hlgOetf(linearColor);
+  const int COLOR_TRANSFER_HLG = 7;
+  if (uOetfColorTransfer == COLOR_TRANSFER_ST2084) {
+    return pqOetf(linearColor);
+  } else if (uOetfColorTransfer == COLOR_TRANSFER_HLG) {
+    return hlgOetf(linearColor);
+  } else {
+    // Output red as an obviously visible error.
+    return vec3(1.0, 0.0, 0.0);
+  }
 }
 
 void main() {
   vec4 inputColor = texture(uTexSampler, vTexSamplingCoord);
+  // transformedColors is an optical color.
   vec4 transformedColors = uRgbMatrix * vec4(inputColor.rgb, 1);
   outColor = vec4(getElectricalColor(transformedColors.rgb), inputColor.a);
 }

library/effect/src/main/assets/shaders/fragment_shader_transformation_external_yuv_es3.glsl

@@ -86,12 +86,17 @@ highp vec3 getOpticalColor(highp vec3 electricalColor) {
   const int COLOR_TRANSFER_ST2084 = 6;
   const int COLOR_TRANSFER_HLG = 7;
 
+  const int FORMAT_NO_VALUE = -1;
+
   if (uEotfColorTransfer == COLOR_TRANSFER_ST2084) {
     return pqEotf(electricalColor);
   } else if (uEotfColorTransfer == COLOR_TRANSFER_HLG) {
     return hlgEotf(electricalColor);
-  } else {
+  } else if (uEotfColorTransfer == FORMAT_NO_VALUE) {
     return electricalColor;
+  } else {
+    // Output red as an obviously visible error.
+    return vec3(1.0, 0.0, 0.0);
   }
 }