Allow YCgCoRe and YCgCoRo decoding.

.github/workflows/ci-fuzztest.yml

@@ -49,7 +49,7 @@ jobs:
           -DAVIF_LIBYUV=${{ matrix.libyuv }}
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
-          -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
+          -DAVIF_ENABLE_YCGCO_R_ENCODING=ON
           -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON

.github/workflows/ci-linux-static-old-local.yml

@@ -50,7 +50,7 @@ jobs:
           -DAVIF_LOCAL_LIBSHARPYUV=ON -DAVIF_LOCAL_LIBXML2=ON -DAVIF_LOCAL_LIBYUV=ON
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_LOCAL_GTEST=ON
-          -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
+          -DAVIF_ENABLE_YCGCO_R_ENCODING=ON
           -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_WERROR=ON

.github/workflows/ci-unix-shared-local.yml

@@ -54,7 +54,7 @@ jobs:
           -DAVIF_LIBYUV=${{ matrix.libyuv }}
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
-          -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
+          -DAVIF_ENABLE_YCGCO_R_ENCODING=ON
           -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON

.github/workflows/ci-unix-static.yml

@@ -58,7 +58,7 @@ jobs:
           -DAVIF_LIBSHARPYUV=LOCAL -DAVIF_LIBXML2=LOCAL -DAVIF_LIBYUV=LOCAL
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
-          -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
+          -DAVIF_ENABLE_YCGCO_R_ENCODING=ON
           -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON

.github/workflows/ci-windows-installed.yml

@@ -73,7 +73,7 @@ jobs:
           -DAVIF_LIBYUV=SYSTEM -DAVIF_ZLIBPNG=SYSTEM
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
-          -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
+          -DAVIF_ENABLE_YCGCO_R_ENCODING=ON
           -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON

.github/workflows/ci-windows-shared-local.yml

@@ -53,7 +53,7 @@ jobs:
           -DAVIF_LIBYUV=LOCAL -DAVIF_ZLIBPNG=LOCAL
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
-          -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
+          -DAVIF_ENABLE_YCGCO_R_ENCODING=ON
           -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON

.github/workflows/ci-windows.yml

@@ -66,7 +66,7 @@ jobs:
           -DAVIF_LIBYUV=LOCAL -DAVIF_ZLIBPNG=LOCAL
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
-          -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
+          -DAVIF_ENABLE_YCGCO_R_ENCODING=ON
           -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON

CHANGELOG.md

@@ -33,6 +33,8 @@ The changes are relative to the previous release, unless the baseline is specifi
   avifGainMapMetadataDouble structs.
 * Add avif(Un)SignedFraction structs and avifDoubleTo(Un)SignedFraction
   utility functions.
+* Allow YCgCo_Re and YCgCo_Ro decoding by default. Encoding is still conditioned
+  to the AVIF_ENABLE_YCGCO_R_ENCODING CMake flag.
 
 ## [1.1.1] - 2024-07-30
 

CMakeLists.txt

@@ -64,7 +64,7 @@ option(BUILD_SHARED_LIBS "Build shared avif library" ON)
 
 option(AVIF_ENABLE_WERROR "Treat all compiler warnings as errors" OFF)
 
-option(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R "Enable experimental YCgCo-R matrix code" OFF)
+option(AVIF_ENABLE_YCGCO_R_ENCODING "Enable YCgCo-R matrix codes for encoding" OFF)
 option(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP
        "Enable experimental gain map code (for HDR images that look good both on HDR and SDR displays)" OFF
 )
@@ -360,8 +360,8 @@ if(AVIF_ENABLE_COVERAGE)
     endif()
 endif()
 
-if(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
-    add_compile_definitions(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
+if(AVIF_ENABLE_YCGCO_R_ENCODING)
+    add_compile_definitions(AVIF_ENABLE_YCGCO_R_ENCODING)
 endif()
 
 if(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP)

apps/avifenc.c

@@ -1936,12 +1936,12 @@ int main(int argc, char * argv[])
         // Matrix coefficients.
         if (settings.cicpExplicitlySet) {
             avifBool incompatibleMC = (settings.matrixCoefficients != AVIF_MATRIX_COEFFICIENTS_IDENTITY);
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
+#if defined(AVIF_ENABLE_YCGCO_R_ENCODING)
             incompatibleMC &= (settings.matrixCoefficients != AVIF_MATRIX_COEFFICIENTS_YCGCO_RE &&
                                settings.matrixCoefficients != AVIF_MATRIX_COEFFICIENTS_YCGCO_RO);
 #endif
             if (incompatibleMC) {
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
+#if defined(AVIF_ENABLE_YCGCO_R_ENCODING)
                 fprintf(stderr, "Matrix coefficients have to be identity, YCgCo-Re, or YCgCo-Ro in lossless mode.\n");
 #else
                 fprintf(stderr, "Matrix coefficients have to be identity in lossless mode.\n");
@@ -2374,12 +2374,12 @@ int main(int argc, char * argv[])
             }
 
             avifBool matrixCoefficientsAreLosslessCompatible = usingIdentityMatrix;
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
+#if defined(AVIF_ENABLE_YCGCO_R_ENCODING)
             matrixCoefficientsAreLosslessCompatible |= (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE ||
                                                         image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO);
 #endif
             if (!matrixCoefficientsAreLosslessCompatible && !using400) {
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
+#if defined(AVIF_ENABLE_YCGCO_R_ENCODING)
                 fprintf(stderr, "WARNING: [--lossless] Input data was RGB and matrixCoefficients isn't set to identity (--cicp x/x/0) or YCgCo-Re/Ro (--cicp x/x/16 or x/x/17); Output might not be lossless.\n");
 #else
                 fprintf(stderr, "WARNING: [--lossless] Input data was RGB and matrixCoefficients isn't set to identity (--cicp x/x/0); Output might not be lossless.\n");

apps/shared/avifjpeg.c

@@ -938,22 +938,15 @@ static avifBool avifJPEGReadInternal(FILE * f,
 
         avif->width = cinfo.output_width;
         avif->height = cinfo.output_height;
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
         const avifBool useYCgCoR = (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE ||
                                     avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO);
-#endif
         if (avif->yuvFormat == AVIF_PIXEL_FORMAT_NONE) {
             // Identity and YCgCo-R are only valid with YUV444.
-            avif->yuvFormat = (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_IDENTITY
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
-                               || useYCgCoR
-#endif
-                               )
+            avif->yuvFormat = (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_IDENTITY || useYCgCoR)
                                   ? AVIF_PIXEL_FORMAT_YUV444
                                   : AVIF_APP_DEFAULT_PIXEL_FORMAT;
         }
         avif->depth = requestedDepth ? requestedDepth : 8;
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
         if (useYCgCoR) {
             if (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO) {
                 fprintf(stderr, "AVIF_MATRIX_COEFFICIENTS_YCGCO_RO cannot be used with JPEG because it has an even bit depth.\n");
@@ -965,7 +958,6 @@ static avifBool avifJPEGReadInternal(FILE * f,
             }
             avif->depth = 10;
         }
-#endif
         avifRGBImageSetDefaults(&rgb, avif);
         rgb.format = AVIF_RGB_FORMAT_RGB;
         rgb.chromaDownsampling = chromaDownsampling;

apps/shared/avifpng.c

@@ -317,21 +317,15 @@ avifBool avifPNGRead(const char * inputFilename,
     avif->width = rawWidth;
     avif->height = rawHeight;
     avif->yuvFormat = requestedFormat;
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
     if (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO) {
         fprintf(stderr, "AVIF_MATRIX_COEFFICIENTS_YCGCO_RO cannot be used with PNG because it has an even bit depth.\n");
         goto cleanup;
     }
-    const avifBool useYCgCoR = (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE);
-#endif
     if (avif->yuvFormat == AVIF_PIXEL_FORMAT_NONE) {
         if ((rawColorType == PNG_COLOR_TYPE_GRAY) || (rawColorType == PNG_COLOR_TYPE_GRAY_ALPHA)) {
             avif->yuvFormat = AVIF_PIXEL_FORMAT_YUV400;
-        } else if (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_IDENTITY
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
-                   || useYCgCoR
-#endif
-        ) {
+        } else if (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_IDENTITY ||
+                   avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE) {
             // Identity and YCgCo-R are only valid with YUV444.
             avif->yuvFormat = AVIF_PIXEL_FORMAT_YUV444;
         } else {
@@ -346,8 +340,7 @@ avifBool avifPNGRead(const char * inputFilename,
             avif->depth = 12;
         }
     }
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
-    if (useYCgCoR) {
+    if (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE) {
         if (imgBitDepth != 8) {
             fprintf(stderr, "AVIF_MATRIX_COEFFICIENTS_YCGCO_RE cannot be used on 16 bit input because it adds two bits.\n");
             goto cleanup;
@@ -358,7 +351,6 @@ avifBool avifPNGRead(const char * inputFilename,
         }
         avif->depth = 10;
     }
-#endif
 
     if (!ignoreColorProfile) {
         char * iccpProfileName = NULL;
@@ -541,7 +533,6 @@ avifBool avifPNGWrite(const char * outputFilename, const avifImage * avif, uint3
     if (rgbDepth == 0) {
         rgbDepth = (avif->depth > 8) ? 16 : 8;
     }
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
     if (avif->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO) {
         fprintf(stderr, "AVIF_MATRIX_COEFFICIENTS_YCGCO_RO cannot be used with PNG because it has an even bit depth.\n");
         goto cleanup;
@@ -558,7 +549,6 @@ avifBool avifPNGWrite(const char * outputFilename, const avifImage * avif, uint3
 
         rgbDepth = 8;
     }
-#endif
 
     volatile avifBool monochrome8bit = (avif->yuvFormat == AVIF_PIXEL_FORMAT_YUV400) && !avif->alphaPlane && (avif->depth == 8) &&
                                        (rgbDepth == 8);

include/avif/avif.h

@@ -399,10 +399,8 @@ enum
     AVIF_MATRIX_COEFFICIENTS_CHROMA_DERIVED_NCL = 12,
     AVIF_MATRIX_COEFFICIENTS_CHROMA_DERIVED_CL = 13,
     AVIF_MATRIX_COEFFICIENTS_ICTCP = 14,
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
     AVIF_MATRIX_COEFFICIENTS_YCGCO_RE = 16,
     AVIF_MATRIX_COEFFICIENTS_YCGCO_RO = 17,
-#endif
     AVIF_MATRIX_COEFFICIENTS_LAST
 };
 typedef uint16_t avifMatrixCoefficients; // AVIF_MATRIX_COEFFICIENTS_*

include/avif/internal.h

@@ -252,10 +252,8 @@ typedef enum avifReformatMode
     AVIF_REFORMAT_MODE_YUV_COEFFICIENTS = 0, // Normal YUV conversion using coefficients
     AVIF_REFORMAT_MODE_IDENTITY,             // Pack GBR directly into YUV planes (AVIF_MATRIX_COEFFICIENTS_IDENTITY)
     AVIF_REFORMAT_MODE_YCGCO,                // YUV conversion using AVIF_MATRIX_COEFFICIENTS_YCGCO
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
-    AVIF_REFORMAT_MODE_YCGCO_RE, // YUV conversion using AVIF_MATRIX_COEFFICIENTS_YCGCO_RE
-    AVIF_REFORMAT_MODE_YCGCO_RO, // YUV conversion using AVIF_MATRIX_COEFFICIENTS_YCGCO_RO
-#endif
+    AVIF_REFORMAT_MODE_YCGCO_RE,             // YUV conversion using AVIF_MATRIX_COEFFICIENTS_YCGCO_RE
+    AVIF_REFORMAT_MODE_YCGCO_RO,             // YUV conversion using AVIF_MATRIX_COEFFICIENTS_YCGCO_RO
 } avifReformatMode;
 
 typedef enum avifAlphaMultiplyMode

src/reformat.c

@@ -96,11 +96,6 @@ avifBool avifGetRGBColorSpaceInfo(const avifRGBImage * rgb, avifRGBColorSpaceInf
 
 avifBool avifGetYUVColorSpaceInfo(const avifImage * image, avifYUVColorSpaceInfo * info)
 {
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
-    const avifBool useYCgCo = (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE) ||
-                              (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO);
-#endif
-
     AVIF_CHECK(image->depth == 8 || image->depth == 10 || image->depth == 12 || image->depth == 16);
     AVIF_CHECK(image->yuvFormat >= AVIF_PIXEL_FORMAT_YUV444 && image->yuvFormat < AVIF_PIXEL_FORMAT_COUNT);
     AVIF_CHECK(image->yuvRange == AVIF_RANGE_LIMITED || image->yuvRange == AVIF_RANGE_FULL);
@@ -110,11 +105,8 @@ avifBool avifGetYUVColorSpaceInfo(const avifImage * image, avifYUVColorSpaceInfo
     // YCgCo performs limited-full range adjustment on R,G,B but the current implementation performs range adjustment
     // on Y,U,V. So YCgCo with limited range is unsupported.
     if ((image->matrixCoefficients == 3 /* CICP reserved */) ||
-        ((image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
-          || useYCgCo
-#endif
-          ) &&
+        ((image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO || image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE ||
+          image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO) &&
          (image->yuvRange == AVIF_RANGE_LIMITED)) ||
         (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_BT2020_CL) ||
         (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_SMPTE2085) ||
@@ -146,7 +138,6 @@ avifBool avifGetYUVColorSpaceInfo(const avifImage * image, avifYUVColorSpaceInfo
 
 static avifBool avifPrepareReformatState(const avifImage * image, const avifRGBImage * rgb, avifReformatState * state)
 {
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
     const avifBool useYCgCoRe = (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE);
     const avifBool useYCgCoRo = (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO);
     if (useYCgCoRe || useYCgCoRo) {
@@ -155,7 +146,6 @@ static avifBool avifPrepareReformatState(const avifImage * image, const avifRGBI
             return AVIF_FALSE;
         }
     }
-#endif
 
     AVIF_CHECK(avifGetRGBColorSpaceInfo(rgb, &state->rgb));
     AVIF_CHECK(avifGetYUVColorSpaceInfo(image, &state->yuv));
@@ -166,12 +156,10 @@ static avifBool avifPrepareReformatState(const avifImage * image, const avifRGBI
         state->yuv.mode = AVIF_REFORMAT_MODE_IDENTITY;
     } else if (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO) {
         state->yuv.mode = AVIF_REFORMAT_MODE_YCGCO;
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
     } else if (useYCgCoRe) {
         state->yuv.mode = AVIF_REFORMAT_MODE_YCGCO_RE;
     } else if (useYCgCoRo) {
         state->yuv.mode = AVIF_REFORMAT_MODE_YCGCO_RO;
-#endif
     }
 
     if (state->yuv.mode != AVIF_REFORMAT_MODE_YUV_COEFFICIENTS) {
@@ -196,12 +184,8 @@ static int avifYUVColorSpaceInfoUVToUNorm(avifYUVColorSpaceInfo * info, float v)
 
     // YCgCo performs limited-full range adjustment on R,G,B but the current implementation performs range adjustment
     // on Y,U,V. So YCgCo with limited range is unsupported.
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
     assert((info->mode != AVIF_REFORMAT_MODE_YCGCO && info->mode != AVIF_REFORMAT_MODE_YCGCO_RE && info->mode != AVIF_REFORMAT_MODE_YCGCO_RO) ||
            (info->range == AVIF_RANGE_FULL));
-#else
-    assert((info->mode != AVIF_REFORMAT_MODE_YCGCO) || (info->range == AVIF_RANGE_FULL));
-#endif
 
     if (info->mode == AVIF_REFORMAT_MODE_IDENTITY) {
         unorm = (int)avifRoundf(v * info->rangeY + info->biasY);
@@ -359,7 +343,6 @@ avifResult avifImageRGBToYUV(avifImage * image, const avifRGBImage * rgb)
                             yuvBlock[bI][bJ].y = 0.5f * rgbPixel[1] + 0.25f * (rgbPixel[0] + rgbPixel[2]);
                             yuvBlock[bI][bJ].u = 0.5f * rgbPixel[1] - 0.25f * (rgbPixel[0] + rgbPixel[2]);
                             yuvBlock[bI][bJ].v = 0.5f * (rgbPixel[0] - rgbPixel[2]);
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
                         } else if (state.yuv.mode == AVIF_REFORMAT_MODE_YCGCO_RE || state.yuv.mode == AVIF_REFORMAT_MODE_YCGCO_RO) {
                             // Formulas 58,59,60,61 from https://www.itu.int/rec/T-REC-H.273-202407-P
                             const int R = (int)avifRoundf(AVIF_CLAMP(rgbPixel[0] * rgbMaxChannelF, 0.0f, rgbMaxChannelF));
@@ -371,7 +354,6 @@ avifResult avifImageRGBToYUV(avifImage * image, const avifRGBImage * rgb)
                             yuvBlock[bI][bJ].y = (t + (Cg >> 1)) / state.yuv.rangeY;
                             yuvBlock[bI][bJ].u = Cg / state.yuv.rangeUV;
                             yuvBlock[bI][bJ].v = Co / state.yuv.rangeUV;
-#endif
                         } else {
                             float Y = (kr * rgbPixel[0]) + (kg * rgbPixel[1]) + (kb * rgbPixel[2]);
                             yuvBlock[bI][bJ].y = Y;
@@ -769,7 +751,6 @@ static avifResult avifImageYUVAnyToRGBAnySlow(const avifImage * image,
                     G = Y + Cb;
                     B = t - Cr;
                     R = t + Cr;
-#if defined(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
                 } else if (state->yuv.mode == AVIF_REFORMAT_MODE_YCGCO_RE || state->yuv.mode == AVIF_REFORMAT_MODE_YCGCO_RO) {
                     // YCgCoRe/YCgCoRo: Formulas 62,63,64,65 from https://www.itu.int/rec/T-REC-H.273-202407-P
                     const int YY = unormY;
@@ -782,7 +763,6 @@ static avifResult avifImageYUVAnyToRGBAnySlow(const avifImage * image,
                     G /= rgbMaxChannelF;
                     B /= rgbMaxChannelF;
                     R /= rgbMaxChannelF;
-#endif
                 } else {
                     // Normal YUV
                     R = Y + (2 * (1 - kr)) * Cr;

src/write.c

@@ -1615,6 +1615,16 @@ static avifResult avifValidateGrid(uint32_t gridCols,
             AVIF_ASSERT_OR_RETURN(cellImage->gainMap && cellImage->gainMap->image);
             cellImage = cellImage->gainMap->image;
         }
+#endif
+#if !defined(AVIF_ENABLE_YCGCO_R_ENCODING)
+        if (cellImage->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RE ||
+            cellImage->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO_RO) {
+            avifDiagnosticsPrintf(diag,
+                                  "YCGCO_R is not enabled for encoding. "
+                                  "Please set AVIF_ENABLE_YCGCO_R_ENCODING in CMake. "
+                                  "cf https://github.com/AOMediaCodec/libavif/issues/2077.");
+            return AVIF_RESULT_INVALID_IMAGE_GRID;
+        }
 #endif
         const uint32_t expectedCellWidth = ((cellIndex + 1) % gridCols) ? tileWidth : bottomRightCell->width;
         const uint32_t expectedCellHeight = (cellIndex < (cellCount - gridCols)) ? tileHeight : bottomRightCell->height;