Add MediaConvertWebPToPNG option (telegram). (#741)

* Add MediaConvertWebPToPNG option (telegram).

When enabled matterbridge will convert .webp files to .png files
before uploading them to the mediaserver of the other bridges.

Fixes #398

1 files changed, 603 insertions, 0 deletions

diff --git a/vendor/golang.org/x/image/vp8l/decode.go b/vendor/golang.org/x/image/vp8l/decode.go
new file mode 100644
index 00000000..43194870
--- /dev/null
+++ b/vendor/golang.org/x/image/vp8l/decode.go
@@ -0,0 +1,603 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package vp8l implements a decoder for the VP8L lossless image format.
+//
+// The VP8L specification is at:
+// https://developers.google.com/speed/webp/docs/riff_container
+package vp8l // import "golang.org/x/image/vp8l"
+
+import (
+	"bufio"
+	"errors"
+	"image"
+	"image/color"
+	"io"
+)
+
+var (
+	errInvalidCodeLengths = errors.New("vp8l: invalid code lengths")
+	errInvalidHuffmanTree = errors.New("vp8l: invalid Huffman tree")
+)
+
+// colorCacheMultiplier is the multiplier used for the color cache hash
+// function, specified in section 4.2.3.
+const colorCacheMultiplier = 0x1e35a7bd
+
+// distanceMapTable is the look-up table for distanceMap.
+var distanceMapTable = [120]uint8{
+	0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a,
+	0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a,
+	0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b,
+	0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03,
+	0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c,
+	0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e,
+	0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b,
+	0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f,
+	0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b,
+	0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41,
+	0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f,
+	0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70,
+}
+
+// distanceMap maps a LZ77 backwards reference distance to a two-dimensional
+// pixel offset, specified in section 4.2.2.
+func distanceMap(w int32, code uint32) int32 {
+	if int32(code) > int32(len(distanceMapTable)) {
+		return int32(code) - int32(len(distanceMapTable))
+	}
+	distCode := int32(distanceMapTable[code-1])
+	yOffset := distCode >> 4
+	xOffset := 8 - distCode&0xf
+	if d := yOffset*w + xOffset; d >= 1 {
+		return d
+	}
+	return 1
+}
+
+// decoder holds the bit-stream for a VP8L image.
+type decoder struct {
+	r     io.ByteReader
+	bits  uint32
+	nBits uint32
+}
+
+// read reads the next n bits from the decoder's bit-stream.
+func (d *decoder) read(n uint32) (uint32, error) {
+	for d.nBits < n {
+		c, err := d.r.ReadByte()
+		if err != nil {
+			if err == io.EOF {
+				err = io.ErrUnexpectedEOF
+			}
+			return 0, err
+		}
+		d.bits |= uint32(c) << d.nBits
+		d.nBits += 8
+	}
+	u := d.bits & (1<<n - 1)
+	d.bits >>= n
+	d.nBits -= n
+	return u, nil
+}
+
+// decodeTransform decodes the next transform and the width of the image after
+// transformation (or equivalently, before inverse transformation), specified
+// in section 3.
+func (d *decoder) decodeTransform(w int32, h int32) (t transform, newWidth int32, err error) {
+	t.oldWidth = w
+	t.transformType, err = d.read(2)
+	if err != nil {
+		return transform{}, 0, err
+	}
+	switch t.transformType {
+	case transformTypePredictor, transformTypeCrossColor:
+		t.bits, err = d.read(3)
+		if err != nil {
+			return transform{}, 0, err
+		}
+		t.bits += 2
+		t.pix, err = d.decodePix(nTiles(w, t.bits), nTiles(h, t.bits), 0, false)
+		if err != nil {
+			return transform{}, 0, err
+		}
+	case transformTypeSubtractGreen:
+		// No-op.
+	case transformTypeColorIndexing:
+		nColors, err := d.read(8)
+		if err != nil {
+			return transform{}, 0, err
+		}
+		nColors++
+		t.bits = 0
+		switch {
+		case nColors <= 2:
+			t.bits = 3
+		case nColors <= 4:
+			t.bits = 2
+		case nColors <= 16:
+			t.bits = 1
+		}
+		w = nTiles(w, t.bits)
+		pix, err := d.decodePix(int32(nColors), 1, 4*256, false)
+		if err != nil {
+			return transform{}, 0, err
+		}
+		for p := 4; p < len(pix); p += 4 {
+			pix[p+0] += pix[p-4]
+			pix[p+1] += pix[p-3]
+			pix[p+2] += pix[p-2]
+			pix[p+3] += pix[p-1]
+		}
+		// The spec says that "if the index is equal or larger than color_table_size,
+		// the argb color value should be set to 0x00000000 (transparent black)."
+		// We re-slice up to 256 4-byte pixels.
+		t.pix = pix[:4*256]
+	}
+	return t, w, nil
+}
+
+// repeatsCodeLength is the minimum code length for repeated codes.
+const repeatsCodeLength = 16
+
+// These magic numbers are specified at the end of section 5.2.2.
+// The 3-length arrays apply to code lengths >= repeatsCodeLength.
+var (
+	codeLengthCodeOrder = [19]uint8{
+		17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+	}
+	repeatBits    = [3]uint8{2, 3, 7}
+	repeatOffsets = [3]uint8{3, 3, 11}
+)
+
+// decodeCodeLengths decodes a Huffman tree's code lengths which are themselves
+// encoded via a Huffman tree, specified in section 5.2.2.
+func (d *decoder) decodeCodeLengths(dst []uint32, codeLengthCodeLengths []uint32) error {
+	h := hTree{}
+	if err := h.build(codeLengthCodeLengths); err != nil {
+		return err
+	}
+
+	maxSymbol := len(dst)
+	useLength, err := d.read(1)
+	if err != nil {
+		return err
+	}
+	if useLength != 0 {
+		n, err := d.read(3)
+		if err != nil {
+			return err
+		}
+		n = 2 + 2*n
+		ms, err := d.read(n)
+		if err != nil {
+			return err
+		}
+		maxSymbol = int(ms) + 2
+		if maxSymbol > len(dst) {
+			return errInvalidCodeLengths
+		}
+	}
+
+	// The spec says that "if code 16 [meaning repeat] is used before
+	// a non-zero value has been emitted, a value of 8 is repeated."
+	prevCodeLength := uint32(8)
+
+	for symbol := 0; symbol < len(dst); {
+		if maxSymbol == 0 {
+			break
+		}
+		maxSymbol--
+		codeLength, err := h.next(d)
+		if err != nil {
+			return err
+		}
+		if codeLength < repeatsCodeLength {
+			dst[symbol] = codeLength
+			symbol++
+			if codeLength != 0 {
+				prevCodeLength = codeLength
+			}
+			continue
+		}
+
+		repeat, err := d.read(uint32(repeatBits[codeLength-repeatsCodeLength]))
+		if err != nil {
+			return err
+		}
+		repeat += uint32(repeatOffsets[codeLength-repeatsCodeLength])
+		if symbol+int(repeat) > len(dst) {
+			return errInvalidCodeLengths
+		}
+		// A code length of 16 repeats the previous non-zero code.
+		// A code length of 17 or 18 repeats zeroes.
+		cl := uint32(0)
+		if codeLength == 16 {
+			cl = prevCodeLength
+		}
+		for ; repeat > 0; repeat-- {
+			dst[symbol] = cl
+			symbol++
+		}
+	}
+	return nil
+}
+
+// decodeHuffmanTree decodes a Huffman tree into h.
+func (d *decoder) decodeHuffmanTree(h *hTree, alphabetSize uint32) error {
+	useSimple, err := d.read(1)
+	if err != nil {
+		return err
+	}
+	if useSimple != 0 {
+		nSymbols, err := d.read(1)
+		if err != nil {
+			return err
+		}
+		nSymbols++
+		firstSymbolLengthCode, err := d.read(1)
+		if err != nil {
+			return err
+		}
+		firstSymbolLengthCode = 7*firstSymbolLengthCode + 1
+		var symbols [2]uint32
+		symbols[0], err = d.read(firstSymbolLengthCode)
+		if err != nil {
+			return err
+		}
+		if nSymbols == 2 {
+			symbols[1], err = d.read(8)
+			if err != nil {
+				return err
+			}
+		}
+		return h.buildSimple(nSymbols, symbols, alphabetSize)
+	}
+
+	nCodes, err := d.read(4)
+	if err != nil {
+		return err
+	}
+	nCodes += 4
+	if int(nCodes) > len(codeLengthCodeOrder) {
+		return errInvalidHuffmanTree
+	}
+	codeLengthCodeLengths := [len(codeLengthCodeOrder)]uint32{}
+	for i := uint32(0); i < nCodes; i++ {
+		codeLengthCodeLengths[codeLengthCodeOrder[i]], err = d.read(3)
+		if err != nil {
+			return err
+		}
+	}
+	codeLengths := make([]uint32, alphabetSize)
+	if err = d.decodeCodeLengths(codeLengths, codeLengthCodeLengths[:]); err != nil {
+		return err
+	}
+	return h.build(codeLengths)
+}
+
+const (
+	huffGreen    = 0
+	huffRed      = 1
+	huffBlue     = 2
+	huffAlpha    = 3
+	huffDistance = 4
+	nHuff        = 5
+)
+
+// hGroup is an array of 5 Huffman trees.
+type hGroup [nHuff]hTree
+
+// decodeHuffmanGroups decodes the one or more hGroups used to decode the pixel
+// data. If one hGroup is used for the entire image, then hPix and hBits will
+// be zero. If more than one hGroup is used, then hPix contains the meta-image
+// that maps tiles to hGroup index, and hBits contains the log-2 tile size.
+func (d *decoder) decodeHuffmanGroups(w int32, h int32, topLevel bool, ccBits uint32) (
+	hGroups []hGroup, hPix []byte, hBits uint32, err error) {
+
+	maxHGroupIndex := 0
+	if topLevel {
+		useMeta, err := d.read(1)
+		if err != nil {
+			return nil, nil, 0, err
+		}
+		if useMeta != 0 {
+			hBits, err = d.read(3)
+			if err != nil {
+				return nil, nil, 0, err
+			}
+			hBits += 2
+			hPix, err = d.decodePix(nTiles(w, hBits), nTiles(h, hBits), 0, false)
+			if err != nil {
+				return nil, nil, 0, err
+			}
+			for p := 0; p < len(hPix); p += 4 {
+				i := int(hPix[p])<<8 | int(hPix[p+1])
+				if maxHGroupIndex < i {
+					maxHGroupIndex = i
+				}
+			}
+		}
+	}
+	hGroups = make([]hGroup, maxHGroupIndex+1)
+	for i := range hGroups {
+		for j, alphabetSize := range alphabetSizes {
+			if j == 0 && ccBits > 0 {
+				alphabetSize += 1 << ccBits
+			}
+			if err := d.decodeHuffmanTree(&hGroups[i][j], alphabetSize); err != nil {
+				return nil, nil, 0, err
+			}
+		}
+	}
+	return hGroups, hPix, hBits, nil
+}
+
+const (
+	nLiteralCodes  = 256
+	nLengthCodes   = 24
+	nDistanceCodes = 40
+)
+
+var alphabetSizes = [nHuff]uint32{
+	nLiteralCodes + nLengthCodes,
+	nLiteralCodes,
+	nLiteralCodes,
+	nLiteralCodes,
+	nDistanceCodes,
+}
+
+// decodePix decodes pixel data, specified in section 5.2.2.
+func (d *decoder) decodePix(w int32, h int32, minCap int32, topLevel bool) ([]byte, error) {
+	// Decode the color cache parameters.
+	ccBits, ccShift, ccEntries := uint32(0), uint32(0), ([]uint32)(nil)
+	useColorCache, err := d.read(1)
+	if err != nil {
+		return nil, err
+	}
+	if useColorCache != 0 {
+		ccBits, err = d.read(4)
+		if err != nil {
+			return nil, err
+		}
+		if ccBits < 1 || 11 < ccBits {
+			return nil, errors.New("vp8l: invalid color cache parameters")
+		}
+		ccShift = 32 - ccBits
+		ccEntries = make([]uint32, 1<<ccBits)
+	}
+
+	// Decode the Huffman groups.
+	hGroups, hPix, hBits, err := d.decodeHuffmanGroups(w, h, topLevel, ccBits)
+	if err != nil {
+		return nil, err
+	}
+	hMask, tilesPerRow := int32(0), int32(0)
+	if hBits != 0 {
+		hMask, tilesPerRow = 1<<hBits-1, nTiles(w, hBits)
+	}
+
+	// Decode the pixels.
+	if minCap < 4*w*h {
+		minCap = 4 * w * h
+	}
+	pix := make([]byte, 4*w*h, minCap)
+	p, cachedP := 0, 0
+	x, y := int32(0), int32(0)
+	hg, lookupHG := &hGroups[0], hMask != 0
+	for p < len(pix) {
+		if lookupHG {
+			i := 4 * (tilesPerRow*(y>>hBits) + (x >> hBits))
+			hg = &hGroups[uint32(hPix[i])<<8|uint32(hPix[i+1])]
+		}
+
+		green, err := hg[huffGreen].next(d)
+		if err != nil {
+			return nil, err
+		}
+		switch {
+		case green < nLiteralCodes:
+			// We have a literal pixel.
+			red, err := hg[huffRed].next(d)
+			if err != nil {
+				return nil, err
+			}
+			blue, err := hg[huffBlue].next(d)
+			if err != nil {
+				return nil, err
+			}
+			alpha, err := hg[huffAlpha].next(d)
+			if err != nil {
+				return nil, err
+			}
+			pix[p+0] = uint8(red)
+			pix[p+1] = uint8(green)
+			pix[p+2] = uint8(blue)
+			pix[p+3] = uint8(alpha)
+			p += 4
+
+			x++
+			if x == w {
+				x, y = 0, y+1
+			}
+			lookupHG = hMask != 0 && x&hMask == 0
+
+		case green < nLiteralCodes+nLengthCodes:
+			// We have a LZ77 backwards reference.
+			length, err := d.lz77Param(green - nLiteralCodes)
+			if err != nil {
+				return nil, err
+			}
+			distSym, err := hg[huffDistance].next(d)
+			if err != nil {
+				return nil, err
+			}
+			distCode, err := d.lz77Param(distSym)
+			if err != nil {
+				return nil, err
+			}
+			dist := distanceMap(w, distCode)
+			pEnd := p + 4*int(length)
+			q := p - 4*int(dist)
+			qEnd := pEnd - 4*int(dist)
+			if p < 0 || len(pix) < pEnd || q < 0 || len(pix) < qEnd {
+				return nil, errors.New("vp8l: invalid LZ77 parameters")
+			}
+			for ; p < pEnd; p, q = p+1, q+1 {
+				pix[p] = pix[q]
+			}
+
+			x += int32(length)
+			for x >= w {
+				x, y = x-w, y+1
+			}
+			lookupHG = hMask != 0
+
+		default:
+			// We have a color cache lookup. First, insert previous pixels
+			// into the cache. Note that VP8L assumes ARGB order, but the
+			// Go image.RGBA type is in RGBA order.
+			for ; cachedP < p; cachedP += 4 {
+				argb := uint32(pix[cachedP+0])<<16 |
+					uint32(pix[cachedP+1])<<8 |
+					uint32(pix[cachedP+2])<<0 |
+					uint32(pix[cachedP+3])<<24
+				ccEntries[(argb*colorCacheMultiplier)>>ccShift] = argb
+			}
+			green -= nLiteralCodes + nLengthCodes
+			if int(green) >= len(ccEntries) {
+				return nil, errors.New("vp8l: invalid color cache index")
+			}
+			argb := ccEntries[green]
+			pix[p+0] = uint8(argb >> 16)
+			pix[p+1] = uint8(argb >> 8)
+			pix[p+2] = uint8(argb >> 0)
+			pix[p+3] = uint8(argb >> 24)
+			p += 4
+
+			x++
+			if x == w {
+				x, y = 0, y+1
+			}
+			lookupHG = hMask != 0 && x&hMask == 0
+		}
+	}
+	return pix, nil
+}
+
+// lz77Param returns the next LZ77 parameter: a length or a distance, specified
+// in section 4.2.2.
+func (d *decoder) lz77Param(symbol uint32) (uint32, error) {
+	if symbol < 4 {
+		return symbol + 1, nil
+	}
+	extraBits := (symbol - 2) >> 1
+	offset := (2 + symbol&1) << extraBits
+	n, err := d.read(extraBits)
+	if err != nil {
+		return 0, err
+	}
+	return offset + n + 1, nil
+}
+
+// decodeHeader decodes the VP8L header from r.
+func decodeHeader(r io.Reader) (d *decoder, w int32, h int32, err error) {
+	rr, ok := r.(io.ByteReader)
+	if !ok {
+		rr = bufio.NewReader(r)
+	}
+	d = &decoder{r: rr}
+	magic, err := d.read(8)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	if magic != 0x2f {
+		return nil, 0, 0, errors.New("vp8l: invalid header")
+	}
+	width, err := d.read(14)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	width++
+	height, err := d.read(14)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	height++
+	_, err = d.read(1) // Read and ignore the hasAlpha hint.
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	version, err := d.read(3)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	if version != 0 {
+		return nil, 0, 0, errors.New("vp8l: invalid version")
+	}
+	return d, int32(width), int32(height), nil
+}
+
+// DecodeConfig decodes the color model and dimensions of a VP8L image from r.
+func DecodeConfig(r io.Reader) (image.Config, error) {
+	_, w, h, err := decodeHeader(r)
+	if err != nil {
+		return image.Config{}, err
+	}
+	return image.Config{
+		ColorModel: color.NRGBAModel,
+		Width:      int(w),
+		Height:     int(h),
+	}, nil
+}
+
+// Decode decodes a VP8L image from r.
+func Decode(r io.Reader) (image.Image, error) {
+	d, w, h, err := decodeHeader(r)
+	if err != nil {
+		return nil, err
+	}
+	// Decode the transforms.
+	var (
+		nTransforms    int
+		transforms     [nTransformTypes]transform
+		transformsSeen [nTransformTypes]bool
+		originalW      = w
+	)
+	for {
+		more, err := d.read(1)
+		if err != nil {
+			return nil, err
+		}
+		if more == 0 {
+			break
+		}
+		var t transform
+		t, w, err = d.decodeTransform(w, h)
+		if err != nil {
+			return nil, err
+		}
+		if transformsSeen[t.transformType] {
+			return nil, errors.New("vp8l: repeated transform")
+		}
+		transformsSeen[t.transformType] = true
+		transforms[nTransforms] = t
+		nTransforms++
+	}
+	// Decode the transformed pixels.
+	pix, err := d.decodePix(w, h, 0, true)
+	if err != nil {
+		return nil, err
+	}
+	// Apply the inverse transformations.
+	for i := nTransforms - 1; i >= 0; i-- {
+		t := &transforms[i]
+		pix = inverseTransforms[t.transformType](t, pix, h)
+	}
+	return &image.NRGBA{
+		Pix:    pix,
+		Stride: 4 * int(originalW),
+		Rect:   image.Rect(0, 0, int(originalW), int(h)),
+	}, nil
+}