[performance] move thumbnail generation to go code where possible (#3183)

* wrap thumbnailing code to handle generation natively where possible

* more code comments!

* add even more code comments!

* add code comments about blurhash generation

* maintain image rotation if contained in exif data

* move rotation before resizing

* ensure pix_fmt actually selected by ffprobe, check for alpha layer with gifs

* use linear instead of nearest-neighbour for resizing

* work with image "orientation" instead of "rotation". use default 75% quality for both webp and jpeg generation

* add header to new file

* use thumb extension when getting thumb mime type

* update test models and tests with new media processing

* add suggested code comments

* add note about thumbnail filter count reducing memory usage

3 files changed, 5 insertions, 5 deletions

diff --git a/internal/api/client/instance/instancepatch_test.go b/internal/api/client/instance/instancepatch_test.go
index bb391537e..5c5d59ef8 100644
--- a/internal/api/client/instance/instancepatch_test.go
+++ b/internal/api/client/instance/instancepatch_test.go
@@ -858,7 +858,7 @@ func (suite *InstancePatchTestSuite) TestInstancePatch8() {
   "static_url": "http://localhost:8080/fileserver/01AY6P665V14JJR0AFVRT7311Y/attachment/small/`+instanceAccount.AvatarMediaAttachment.ID+`.webp",`+`
   "thumbnail_static_type": "image/webp",
   "thumbnail_description": "A bouncing little green peglin.",
-  "blurhash": "LE9kG#M}4YtO%dRkWEt5Dmoxx?WC"
+  "blurhash": "LE9as6M}4YtO%dRlWEt6Dmoxx?WC"
 }`, string(instanceV2ThumbnailJson))
 
 	// double extra special bonus: now update the image description without changing the image
diff --git a/internal/api/client/media/mediacreate_test.go b/internal/api/client/media/mediacreate_test.go
index 4c2725681..7f8cc2d87 100644
--- a/internal/api/client/media/mediacreate_test.go
+++ b/internal/api/client/media/mediacreate_test.go
@@ -206,7 +206,7 @@ func (suite *MediaCreateTestSuite) TestMediaCreateSuccessful() {
 			Y: 0.5,
 		},
 	}, *attachmentReply.Meta)
-	suite.Equal("LcBzLU#6RkRn~qvzRjWF?urqV@jc", *attachmentReply.Blurhash)
+	suite.Equal("LjCGfG#6RkRn_NvzRjWF?urqV@a$", *attachmentReply.Blurhash)
 	suite.NotEmpty(attachmentReply.ID)
 	suite.NotEmpty(attachmentReply.URL)
 	suite.NotEmpty(attachmentReply.PreviewURL)
@@ -291,7 +291,7 @@ func (suite *MediaCreateTestSuite) TestMediaCreateSuccessfulV2() {
 			Y: 0.5,
 		},
 	}, *attachmentReply.Meta)
-	suite.Equal("LcBzLU#6RkRn~qvzRjWF?urqV@jc", *attachmentReply.Blurhash)
+	suite.Equal("LjCGfG#6RkRn_NvzRjWF?urqV@a$", *attachmentReply.Blurhash)
 	suite.NotEmpty(attachmentReply.ID)
 	suite.Nil(attachmentReply.URL)
 	suite.NotEmpty(attachmentReply.PreviewURL)
diff --git a/internal/api/fileserver/servefile_test.go b/internal/api/fileserver/servefile_test.go
index 9cd1517e2..33afe34d0 100644
--- a/internal/api/fileserver/servefile_test.go
+++ b/internal/api/fileserver/servefile_test.go
@@ -166,7 +166,7 @@ func (suite *ServeFileTestSuite) TestServeSmallRemoteFileOK() {
 	)
 
 	suite.Equal(http.StatusOK, code)
-	suite.Equal("image/webp", headers.Get("content-type"))
+	suite.Equal("image/jpeg", headers.Get("content-type"))
 	suite.Equal(fileInStorage, body)
 }
 
@@ -212,7 +212,7 @@ func (suite *ServeFileTestSuite) TestServeSmallRemoteFileRecache() {
 	)
 
 	suite.Equal(http.StatusOK, code)
-	suite.Equal("image/webp", headers.Get("content-type"))
+	suite.Equal("image/jpeg", headers.Get("content-type"))
 	suite.Equal(fileInStorage, body)
 }