go.image/cmd/webp-manual-test: new program to test Go's WEBP
compatibility with the C libwebp implementation.
Current status:
104 PASS, 5 FAIL, 109 TOTAL
Of those 5 failures, 3 are because Go doesn't support lossy-with-alpha
yet, and the other 2 (lossless_vec_2_13.webp,
lossy_extreme_probabilities.webp) look like genuine bugs.
LGTM=r
R=r, pascal.massimino
CC=golang-codereviews
https://golang.org/cl/150000043
diff --git a/cmd/webp-manual-test/main.go b/cmd/webp-manual-test/main.go
new file mode 100644
index 0000000..f08c183
--- /dev/null
+++ b/cmd/webp-manual-test/main.go
@@ -0,0 +1,165 @@
+// Program webp-manual-test checks that the Go WEBP library's decodings match
+// the C WEBP library's.
+package main
+
+import (
+ "bytes"
+ "encoding/hex"
+ "flag"
+ "fmt"
+ "image"
+ "io"
+ "log"
+ "os"
+ "os/exec"
+ "path/filepath"
+ "sort"
+ "strings"
+
+ "code.google.com/p/go.image/webp"
+)
+
+var (
+ dwebp = flag.String("dwebp", "", "path to the dwebp program "+
+ "installed from https://developers.google.com/speed/webp/download")
+ testdata = flag.String("testdata", "", "path to the libwebp-test-data directory "+
+ "checked out from https://chromium.googlesource.com/webm/libwebp-test-data")
+)
+
+func main() {
+ flag.Parse()
+ if *dwebp == "" {
+ flag.Usage()
+ log.Fatal("dwebp flag was not specified")
+ }
+ if *testdata == "" {
+ flag.Usage()
+ log.Fatal("testdata flag was not specified")
+ }
+
+ f, err := os.Open(*testdata)
+ if err != nil {
+ log.Fatalf("Open: %v", err)
+ }
+ defer f.Close()
+ names, err := f.Readdirnames(-1)
+ if err != nil {
+ log.Fatalf("Readdirnames: %v", err)
+ }
+ sort.Strings(names)
+
+ nFail, nPass := 0, 0
+ for _, name := range names {
+ if !strings.HasSuffix(name, "webp") {
+ continue
+ }
+ if err := test(name); err != nil {
+ fmt.Printf("FAIL\t%s\t%v\n", name, err)
+ nFail++
+ } else {
+ fmt.Printf("PASS\t%s\n", name)
+ nPass++
+ }
+ }
+ fmt.Printf("%d PASS, %d FAIL, %d TOTAL\n", nPass, nFail, nPass+nFail)
+ if nFail != 0 {
+ os.Exit(1)
+ }
+}
+
+// test tests a single WEBP image.
+func test(name string) error {
+ filename := filepath.Join(*testdata, name)
+ f, err := os.Open(filename)
+ if err != nil {
+ return fmt.Errorf("Open: %v", err)
+ }
+ defer f.Close()
+
+ gotImage, err := webp.Decode(f)
+ if err != nil {
+ return fmt.Errorf("Decode: %v", err)
+ }
+ format, encode := "-pam", encodePAM
+ if _, lossy := gotImage.(*image.YCbCr); lossy {
+ format, encode = "-pgm", encodePGM
+ }
+ got, err := encode(gotImage)
+ if err != nil {
+ return fmt.Errorf("encode: %v", err)
+ }
+
+ stdout := new(bytes.Buffer)
+ stderr := new(bytes.Buffer)
+ c := exec.Command(*dwebp, filename, format, "-o", "/dev/stdout")
+ c.Stdout = stdout
+ c.Stderr = stderr
+ if err := c.Run(); err != nil {
+ os.Stderr.Write(stderr.Bytes())
+ return fmt.Errorf("executing dwebp: %v", err)
+ }
+ want := stdout.Bytes()
+
+ if len(got) != len(want) {
+ return fmt.Errorf("encodings have different length: got %d, want %d", len(got), len(want))
+ }
+ for i, g := range got {
+ if w := want[i]; g != w {
+ return fmt.Errorf("encodings differ at position 0x%x: got 0x%02x, want 0x%02x", i, g, w)
+ }
+ }
+ return nil
+}
+
+// encodePAM encodes gotImage in the PAM format.
+func encodePAM(gotImage image.Image) ([]byte, error) {
+ m, ok := gotImage.(*image.NRGBA)
+ if !ok {
+ return nil, fmt.Errorf("lossless image did not decode to an *image.NRGBA")
+ }
+ b := m.Bounds()
+ w, h := b.Dx(), b.Dy()
+ buf := new(bytes.Buffer)
+ fmt.Fprintf(buf, "P7\nWIDTH %d\nHEIGHT %d\nDEPTH 4\nMAXVAL 255\nTUPLTYPE RGB_ALPHA\nENDHDR\n", w, h)
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ o := m.PixOffset(b.Min.X, y)
+ buf.Write(m.Pix[o : o+4*w])
+ }
+ return buf.Bytes(), nil
+}
+
+// encodePGM encodes gotImage in the PGM format in the IMC4 layout.
+func encodePGM(gotImage image.Image) ([]byte, error) {
+ m, ok := gotImage.(*image.YCbCr)
+ if !ok {
+ return nil, fmt.Errorf("lossy image did not decode to an *image.YCbCr")
+ }
+ if m.SubsampleRatio != image.YCbCrSubsampleRatio420 {
+ return nil, fmt.Errorf("lossy image did not decode to a 4:2:0 YCbCr")
+ }
+ b := m.Bounds()
+ w, h := b.Dx(), b.Dy()
+ w2, h2 := (w+1)/2, (h+1)/2
+ buf := new(bytes.Buffer)
+ fmt.Fprintf(buf, "P5\n%d %d\n255\n", 2*w2, h+h2)
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ o := m.YOffset(b.Min.X, y)
+ buf.Write(m.Y[o : o+w])
+ if w&1 != 0 {
+ buf.WriteByte(0x00)
+ }
+ }
+ for y := b.Min.Y; y < b.Max.Y; y += 2 {
+ o := m.COffset(b.Min.X, y)
+ buf.Write(m.Cb[o : o+w2])
+ buf.Write(m.Cr[o : o+w2])
+ }
+ return buf.Bytes(), nil
+}
+
+// dump can be useful for debugging.
+func dump(w io.Writer, b []byte) {
+ h := hex.Dumper(w)
+ h.Write(b)
+ h.Close()
+}
