From b98866889363bcebddc740b1db7be5fef59b8a89 Mon Sep 17 00:00:00 2001
From: Nova Kwok <n0vad3v@riseup.net>
Date: Tue, 18 Jul 2023 23:17:34 +0800
Subject: [PATCH] Better ReductionEffort (#255)

* Better ReductionEffort

* Bump version
---
 config/config.go   |  2 +-
 encoder/encoder.go | 36 +++++++++++++++++-------------------
 2 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/config/config.go b/config/config.go
index f73fe8d..5416a8f 100644
--- a/config/config.go
+++ b/config/config.go
@@ -58,7 +58,7 @@ var (
 	ProxyMode   bool
 	Prefetch    bool
 	Config      jsonFile
-	Version     = "0.9.5"
+	Version     = "0.9.6"
 	WriteLock   = cache.New(5*time.Minute, 10*time.Minute)
 )
 
diff --git a/encoder/encoder.go b/encoder/encoder.go
index 48e2f48..0eee906 100644
--- a/encoder/encoder.go
+++ b/encoder/encoder.go
@@ -228,18 +228,9 @@ func webpEncoder(p1, p2 string, extraParams config.ExtraParams) error {
 			Lossless:      true,
 			StripMetadata: true,
 		})
-		// If some special images cannot encode with default ReductionEffort(0), then try with 4
-		// Example: https://github.com/webp-sh/webp_server_go/issues/234
-		if err != nil {
-			if strings.Contains(err.Error(), "unable to encode") {
-				log.Warnf("Can't encode source image to WebP with default ReductionEffort, retry using ReductionEffort:4")
-				buf, _, err = img.ExportWebp(&vips.WebpExportParams{
-					Lossless:        true,
-					StripMetadata:   true,
-					ReductionEffort: 4,
-				})
-			}
-		}
+		// Lossless mode will not encount problems as below, because in libvips as code below
+		// 	config.method = ExUtilGetInt(argv[++c], 0, &parse_error);
+		//   use_lossless_preset = 0;   // disable -z option
 	} else {
 		buf, _, err = img.ExportWebp(&vips.WebpExportParams{
 			Quality:       quality,
@@ -250,13 +241,20 @@ func webpEncoder(p1, p2 string, extraParams config.ExtraParams) error {
 		// Example: https://github.com/webp-sh/webp_server_go/issues/234
 		if err != nil {
 			if strings.Contains(err.Error(), "unable to encode") {
-				log.Warnf("Can't encode source image to WebP with default ReductionEffort, retry using ReductionEffort:4")
-				buf, _, err = img.ExportWebp(&vips.WebpExportParams{
-					Quality:         quality,
-					Lossless:        false,
-					StripMetadata:   true,
-					ReductionEffort: 4,
-				})
+				log.Warnf("Can't encode source image to WebP with default ReductionEffort")
+				// Loop through ReductionEffort from 1 to 6
+				for i := 1; i <= 6; i++ {
+					log.Warnf("Retry using ReductionEffort: %d", i)
+					buf, _, err = img.ExportWebp(&vips.WebpExportParams{
+						Quality:         quality,
+						Lossless:        false,
+						StripMetadata:   true,
+						ReductionEffort: i,
+					})
+					if err == nil {
+						break
+					}
+				}
 			}
 		}
 	}