111 lines
2.6 KiB
Go
111 lines
2.6 KiB
Go
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package webp
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import (
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"bytes"
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"fmt"
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"image"
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"image/png"
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"os"
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"testing"
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)
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// hex is like fmt.Sprintf("% x", x) but also inserts dots every 16 bytes, to
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// delineate VP8 macroblock boundaries.
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func hex(x []byte) string {
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buf := new(bytes.Buffer)
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for len(x) > 0 {
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n := len(x)
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if n > 16 {
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n = 16
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}
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fmt.Fprintf(buf, " . % x", x[:n])
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x = x[n:]
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}
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return buf.String()
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}
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func TestDecodeVP8(t *testing.T) {
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// The original video-001.png image is 150x103.
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const w, h = 150, 103
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// w2 and h2 are the half-width and half-height, rounded up.
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const w2, h2 = int((w + 1) / 2), int((h + 1) / 2)
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f0, err := os.Open("../testdata/video-001.webp.ycbcr.png")
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if err != nil {
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t.Fatal(err)
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}
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defer f0.Close()
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img0, err := png.Decode(f0)
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if err != nil {
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t.Fatal(err)
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}
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// The split-into-YCbCr-planes golden image is a 2*w2 wide and h+h2 high
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// gray image arranged in IMC4 format:
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// YYYY
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// YYYY
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// BBRR
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// See http://www.fourcc.org/yuv.php#IMC4
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if got, want := img0.Bounds(), image.Rect(0, 0, 2*w2, h+h2); got != want {
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t.Fatalf("bounds0: got %v, want %v", got, want)
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}
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m0, ok := img0.(*image.Gray)
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if !ok {
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t.Fatal("decoded PNG image is not a Gray")
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}
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f1, err := os.Open("../testdata/video-001.webp")
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if err != nil {
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t.Fatal(err)
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}
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defer f1.Close()
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img1, err := Decode(f1)
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if err != nil {
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t.Fatal(err)
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}
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if got, want := img1.Bounds(), image.Rect(0, 0, w, h); got != want {
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t.Fatalf("bounds1: got %v, want %v", got, want)
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}
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m1, ok := img1.(*image.YCbCr)
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if !ok || m1.SubsampleRatio != image.YCbCrSubsampleRatio420 {
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t.Fatal("decoded WEBP image is not a 4:2:0 YCbCr")
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}
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planes := []struct {
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name string
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m1Pix []uint8
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m1Stride int
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m0Rect image.Rectangle
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}{
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{"Y", m1.Y, m1.YStride, image.Rect(0, 0, w, h)},
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{"Cb", m1.Cb, m1.CStride, image.Rect(0*w2, h, 1*w2, h+h2)},
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{"Cr", m1.Cr, m1.CStride, image.Rect(1*w2, h, 2*w2, h+h2)},
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}
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for _, plane := range planes {
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dx := plane.m0Rect.Dx()
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nDiff, diff := 0, make([]byte, dx)
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for j, y := 0, plane.m0Rect.Min.Y; y < plane.m0Rect.Max.Y; j, y = j+1, y+1 {
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got := plane.m1Pix[j*plane.m1Stride:][:dx]
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want := m0.Pix[y*m0.Stride+plane.m0Rect.Min.X:][:dx]
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if bytes.Equal(got, want) {
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continue
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}
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nDiff++
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if nDiff > 10 {
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t.Errorf("%s plane: more rows differ", plane.name)
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break
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}
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for i := range got {
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diff[i] = got[i] - want[i]
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}
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t.Errorf("%s plane: m0 row %d, m1 row %d\ngot %s\nwant%s\ndiff%s",
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plane.name, y, j, hex(got), hex(want), hex(diff))
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}
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}
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}
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