avifenc: make alpha quality be the same as the color quality by default. (#2548)

If only the color quality is set, alpha quality is automatically set to the
same value.

Author: maryla-uc

CHANGELOG.md

@@ -49,6 +49,7 @@ The changes are relative to the previous release, unless the baseline is specifi
   flags. `-q` or `--qcolor` and `--qalpha` should be used instead.
 * For dependencies, the deprecated way of setting AVIF_LOCAL_* to ON is
   removed. Dependency options can now only be set to OFF/LOCAL/SYSTEM.
+* Change the default quality for alpha to be the same as the quality for color.
 
 ## [1.1.1] - 2024-07-30
 

apps/avifenc.c

@@ -807,7 +807,6 @@ static avifBool avifImageSplitGrid(const avifImage * gridSplitImage, uint32_t gr
 
 #define INVALID_QUALITY (-1)
 #define DEFAULT_QUALITY 60 // Maps to a quantizer (QP) of 25.
-#define DEFAULT_QUALITY_ALPHA AVIF_QUALITY_LOSSLESS
 #define DEFAULT_QUALITY_GAIN_MAP DEFAULT_QUALITY
 #define PROGRESSIVE_WORST_QUALITY 10 // Not doing auto automatic layered encoding below this quality
 #define PROGRESSIVE_START_QUALITY 2  // First layer use this quality
@@ -925,12 +924,6 @@ static avifBool avifEncodeRestOfImageSequence(avifEncoder * encoder,
     while ((nextFile = avifInputGetFile(input, imageIndex)) != NULL) {
         uint64_t nextDurationInTimescales = nextFile->duration ? nextFile->duration : settings->outputTiming.duration;
 
-        printf(" * Encoding frame %d [%" PRIu64 "/%" PRIu64 " ts]: %s\n",
-               imageIndex,
-               nextDurationInTimescales,
-               settings->outputTiming.timescale,
-               nextFile->filename);
-
         if (nextImage) {
             avifImageDestroy(nextImage);
         }
@@ -969,6 +962,17 @@ static avifBool avifEncodeRestOfImageSequence(avifEncoder * encoder,
         if (!avifEncodeUpdateEncoderSettings(encoder, nextSettings)) {
             goto cleanup;
         }
+
+        printf(" * Encoding frame %d [%" PRIu64 "/%" PRIu64 " ts] color quality [%d (%s)], alpha quality [%d (%s)]: %s\n",
+               imageIndex,
+               nextDurationInTimescales,
+               settings->outputTiming.timescale,
+               encoder->quality,
+               qualityString(encoder->quality),
+               encoder->qualityAlpha,
+               qualityString(encoder->qualityAlpha),
+               nextFile->filename);
+
         const avifResult nextImageResult = avifEncoderAddImage(encoder, nextImage, nextDurationInTimescales, AVIF_ADD_IMAGE_FLAG_NONE);
         if (nextImageResult != AVIF_RESULT_OK) {
             fprintf(stderr, "ERROR: Failed to encode image: %s\n", avifResultToString(nextImageResult));
@@ -1150,7 +1154,7 @@ static avifBool avifEncodeImagesFixedQuality(const avifSettings * settings,
     }
 #endif
 
-    printf("Encoding with codec '%s' speed [%s], color quality [%d (%s)], alpha quality [%d (%s)]%s, %s, %d worker thread(s), please wait...\n",
+    printf("Encoding with initial settings: codec '%s' speed [%s], color quality [%d (%s)], alpha quality [%d (%s)]%s, %s, %d worker thread(s), please wait...\n",
            codecName ? codecName : "none",
            speedStr,
            encoder->quality,
@@ -1195,10 +1199,14 @@ static avifBool avifEncodeImagesFixedQuality(const avifSettings * settings,
 
         uint64_t firstDurationInTimescales = firstFile->duration ? firstFile->duration : settings->outputTiming.duration;
         if (input->useStdin || (settings->layers == 1 && input->filesCount > 1)) {
-            printf(" * Encoding frame %d [%" PRIu64 "/%" PRIu64 " ts]: %s\n",
+            printf(" * Encoding frame %d [%" PRIu64 "/%" PRIu64 " ts] color quality [%d (%s)], alpha quality [%d (%s)]: %s\n",
                    0,
                    firstDurationInTimescales,
                    settings->outputTiming.timescale,
+                   encoder->quality,
+                   qualityString(encoder->quality),
+                   encoder->qualityAlpha,
+                   qualityString(encoder->qualityAlpha),
                    firstFile->filename);
         }
         const avifResult addImageResult = avifEncoderAddImage(encoder, firstImage, firstDurationInTimescales, addImageFlags);
@@ -1898,6 +1906,15 @@ int main(int argc, char * argv[])
         ++argIndex;
     }
 
+    // Alpha quality defaults to the same value as (color) quality until the first time it's explicitly set.
+    for (int i = 0; i < input.filesCount; ++i) {
+        avifInputFileSettings * fileSettings = &input.files[i].settings;
+        if (fileSettings->qualityAlpha.set) {
+            break;
+        }
+        fileSettings->qualityAlpha = fileSettings->quality;
+    }
+
     if (settings.jobs == -1) {
         settings.jobs = avifQueryCPUCount();
     }
@@ -2146,7 +2163,7 @@ int main(int argc, char * argv[])
                 } else {
                     assert(!fileSettings->maxQuantizerAlpha.set);
                     if (!fileSettings->qualityAlpha.set) {
-                        fileSettings->qualityAlpha = intSettingsEntryOf(DEFAULT_QUALITY_ALPHA);
+                        fileSettings->qualityAlpha = fileSettings->quality;
                     }
                     fileSettings->minQuantizerAlpha = intSettingsEntryOf(AVIF_QUANTIZER_BEST_QUALITY);
                     fileSettings->maxQuantizerAlpha = intSettingsEntryOf(AVIF_QUANTIZER_WORST_QUALITY);

tests/test_cmd.sh

@@ -130,17 +130,17 @@ pushd ${TMP_DIR}
   # The default quality is 60. The default alpha quality is 100 (lossless).
   "${AVIFENC}" -s 10 "${INPUT_Y4M}" "${ENCODED_FILE}" > "${OUT_MSG}"
   grep " color quality \[60 " "${OUT_MSG}"
-  grep " alpha quality \[100 " "${OUT_MSG}"
+  grep " alpha quality \[60 " "${OUT_MSG}"
   "${AVIFENC}" -s 10 -q 85 "${INPUT_Y4M}" "${ENCODED_FILE}" > "${OUT_MSG}"
   grep " color quality \[85 " "${OUT_MSG}"
-  grep " alpha quality \[100 " "${OUT_MSG}"
+  grep " alpha quality \[85 " "${OUT_MSG}"
   # The average of 15 and 25 is 20. Quantizer 20 maps to quality 68.
   "${AVIFENC}" -s 10 --min 15 --max 25 "${INPUT_Y4M}" "${ENCODED_FILE}" > "${OUT_MSG}"
   grep " color quality \[68 " "${OUT_MSG}"
-  grep " alpha quality \[100 " "${OUT_MSG}"
+  grep " alpha quality \[68 " "${OUT_MSG}"
   "${AVIFENC}" -s 10 -q 65 --min 15 --max 25 "${INPUT_Y4M}" "${ENCODED_FILE}" > "${OUT_MSG}"
   grep " color quality \[65 " "${OUT_MSG}"
-  grep " alpha quality \[100 " "${OUT_MSG}"
+  grep " alpha quality \[65 " "${OUT_MSG}"
 popd
 
 exit 0

tests/test_cmd_animation.sh

@@ -52,6 +52,15 @@ cleanup() {
 }
 trap cleanup EXIT
 
+# Looks for a string (NOT a regex) in a string.
+# findstr needle haystack
+findstr() {
+  if ! echo "${2}" | grep -F "${1}"; then
+    echo "ERROR: String '${1}' not found"
+    return 1
+  fi
+}
+
 pushd ${TMP_DIR}
   # Lossy test.
   "${AVIFENC}" -s 8 "${INPUT_Y4M_0}" "${INPUT_Y4M_1}" -o "${ENCODED_FILE}"
@@ -73,11 +82,26 @@ pushd ${TMP_DIR}
   "${AVIFENC}" -s 8 -q 60 "${INPUT_Y4M_0}" "${INPUT_Y4M_1}" -o "${ENCODED_FILE}"
   "${AVIFDEC}" "${ENCODED_FILE}" "${DECODED_FILE}"
   Q60_FILE_SIZE=$(wc -c < "${ENCODED_FILE}")
-  "${AVIFENC}" -s 8 -q 60 "${INPUT_Y4M_0}" -q:u 100 "${INPUT_Y4M_1}" -o "${ENCODED_FILE}"
+  out=$("${AVIFENC}" -s 8 -q 60 "${INPUT_Y4M_0}" -q:u 100 "${INPUT_Y4M_1}" -o "${ENCODED_FILE}")
+  findstr "Encoding frame 0 [1/25 ts] color quality [60 (Medium)], alpha quality [60 (Medium)]" "${out}"
+  findstr "Encoding frame 1 [1/25 ts] color quality [100 (Lossless)], alpha quality [100 (Lossless)]" "${out}"
   "${AVIFDEC}" "${ENCODED_FILE}" "${DECODED_FILE}"
   Q60_Q100_FILE_SIZE=$(wc -c < "${ENCODED_FILE}")
   [[ ${Q60_FILE_SIZE} -lt ${Q60_Q100_FILE_SIZE} ]] || exit 1
 
+  # Test updating of q and qalpha. Alpha quality defaults to the same as color quality
+  # until the first time it's explicitly set.
+  out=$("${AVIFENC}" -s 8 -q 70 "${INPUT_Y4M_0}" -q:u 20 "${INPUT_Y4M_1}" --qalpha:u 10 "${INPUT_Y4M_0}" -q:u 30 "${INPUT_Y4M_1}" -o "${ENCODED_FILE}")
+  findstr "Encoding frame 0 [1/25 ts] color quality [70 (Medium)], alpha quality [70 (Medium)]" "${out}"
+  findstr "Encoding frame 1 [1/25 ts] color quality [20 (Low)], alpha quality [20 (Low)]" "${out}"
+  findstr "Encoding frame 2 [1/25 ts] color quality [20 (Low)], alpha quality [10 (Low)]" "${out}"
+  findstr "Encoding frame 3 [1/25 ts] color quality [30 (Low)], alpha quality [10 (Low)]" "${out}"
+  out=$("${AVIFENC}" -s 8 --qalpha 50 -q 70 "${INPUT_Y4M_0}" -q:u 20 "${INPUT_Y4M_1}" -o "${ENCODED_FILE}")
+  findstr "Encoding frame 0 [1/25 ts] color quality [70 (Medium)], alpha quality [50 (Medium)]" "${out}"
+  findstr "Encoding frame 1 [1/25 ts] color quality [20 (Low)], alpha quality [50 (Medium)]" "${out}"
+  out=$("${AVIFENC}" -s 8 "${INPUT_Y4M_0}" "${INPUT_Y4M_1}" -o "${ENCODED_FILE}")
+  findstr "Encoding frame 0 [1/25 ts] color quality [60 (Medium)], alpha quality [60 (Medium)]" "${out}"
+  findstr "Encoding frame 1 [1/25 ts] color quality [60 (Medium)], alpha quality [60 (Medium)]" "${out}"
 popd
 
 exit 0

tests/test_cmd_avm.sh

@@ -86,17 +86,17 @@ pushd ${TMP_DIR}
   # The default quality is 60. The default alpha quality is 100 (lossless).
   "${AVIFENC}" -c avm -s 10 "${INPUT_PNG}" "${ENCODED_FILE}" > "${OUT_MSG}"
   grep " color quality \[60 " "${OUT_MSG}"
-  grep " alpha quality \[100 " "${OUT_MSG}"
+  grep " alpha quality \[60 " "${OUT_MSG}"
   "${AVIFENC}" -c avm -s 10 -q 85 "${INPUT_PNG}" "${ENCODED_FILE}" > "${OUT_MSG}"
   grep " color quality \[85 " "${OUT_MSG}"
-  grep " alpha quality \[100 " "${OUT_MSG}"
+  grep " alpha quality \[85 " "${OUT_MSG}"
   # The average of 15 and 25 is 20. Quantizer 20 maps to quality 68.
   "${AVIFENC}" -c avm -s 10 --min 15 --max 25 "${INPUT_PNG}" "${ENCODED_FILE}" > "${OUT_MSG}"
   grep " color quality \[68 " "${OUT_MSG}"
-  grep " alpha quality \[100 " "${OUT_MSG}"
+  grep " alpha quality \[68 " "${OUT_MSG}"
   "${AVIFENC}" -c avm -s 10 -q 65 --min 15 --max 25 "${INPUT_PNG}" "${ENCODED_FILE}" > "${OUT_MSG}"
   grep " color quality \[65 " "${OUT_MSG}"
-  grep " alpha quality \[100 " "${OUT_MSG}"
+  grep " alpha quality \[65 " "${OUT_MSG}"
 popd
 
 exit 0