mirror of
https://github.com/cwinfo/matterbridge.git
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26a7e35f27
* 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
443 lines
13 KiB
Go
443 lines
13 KiB
Go
// Copyright 2011 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 vp8
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// This file implements decoding DCT/WHT residual coefficients and
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// reconstructing YCbCr data equal to predicted values plus residuals.
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//
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// There are 1*16*16 + 2*8*8 + 1*4*4 coefficients per macroblock:
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// - 1*16*16 luma DCT coefficients,
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// - 2*8*8 chroma DCT coefficients, and
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// - 1*4*4 luma WHT coefficients.
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// Coefficients are read in lots of 16, and the later coefficients in each lot
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// are often zero.
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//
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// The YCbCr data consists of 1*16*16 luma values and 2*8*8 chroma values,
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// plus previously decoded values along the top and left borders. The combined
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// values are laid out as a [1+16+1+8][32]uint8 so that vertically adjacent
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// samples are 32 bytes apart. In detail, the layout is:
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//
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// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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// . . . . . . . a b b b b b b b b b b b b b b b b c c c c . . . . 0
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 1
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 2
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 3
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y c c c c . . . . 4
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 5
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 6
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 7
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y c c c c . . . . 8
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 9
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 10
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 11
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y c c c c . . . . 12
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 13
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 14
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 15
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// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 16
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// . . . . . . . e f f f f f f f f . . . . . . . g h h h h h h h h 17
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// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 18
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// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 19
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// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 20
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// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 21
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// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 22
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// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 23
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// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 24
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// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 25
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//
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// Y, B and R are the reconstructed luma (Y) and chroma (B, R) values.
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// The Y values are predicted (either as one 16x16 region or 16 4x4 regions)
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// based on the row above's Y values (some combination of {abc} or {dYC}) and
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// the column left's Y values (either {ad} or {bY}). Similarly, B and R values
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// are predicted on the row above and column left of their respective 8x8
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// region: {efi} for B, {ghj} for R.
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//
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// For uppermost macroblocks (i.e. those with mby == 0), the {abcefgh} values
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// are initialized to 0x81. Otherwise, they are copied from the bottom row of
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// the macroblock above. The {c} values are then duplicated from row 0 to rows
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// 4, 8 and 12 of the ybr workspace.
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// Similarly, for leftmost macroblocks (i.e. those with mbx == 0), the {adeigj}
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// values are initialized to 0x7f. Otherwise, they are copied from the right
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// column of the macroblock to the left.
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// For the top-left macroblock (with mby == 0 && mbx == 0), {aeg} is 0x81.
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//
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// When moving from one macroblock to the next horizontally, the {adeigj}
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// values can simply be copied from the workspace to itself, shifted by 8 or
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// 16 columns. When moving from one macroblock to the next vertically,
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// filtering can occur and hence the row values have to be copied from the
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// post-filtered image instead of the pre-filtered workspace.
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const (
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bCoeffBase = 1*16*16 + 0*8*8
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rCoeffBase = 1*16*16 + 1*8*8
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whtCoeffBase = 1*16*16 + 2*8*8
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)
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const (
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ybrYX = 8
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ybrYY = 1
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ybrBX = 8
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ybrBY = 18
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ybrRX = 24
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ybrRY = 18
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)
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// prepareYBR prepares the {abcdefghij} elements of ybr.
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func (d *Decoder) prepareYBR(mbx, mby int) {
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if mbx == 0 {
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for y := 0; y < 17; y++ {
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d.ybr[y][7] = 0x81
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}
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for y := 17; y < 26; y++ {
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d.ybr[y][7] = 0x81
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d.ybr[y][23] = 0x81
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}
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} else {
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for y := 0; y < 17; y++ {
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d.ybr[y][7] = d.ybr[y][7+16]
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}
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for y := 17; y < 26; y++ {
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d.ybr[y][7] = d.ybr[y][15]
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d.ybr[y][23] = d.ybr[y][31]
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}
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}
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if mby == 0 {
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for x := 7; x < 28; x++ {
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d.ybr[0][x] = 0x7f
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}
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for x := 7; x < 16; x++ {
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d.ybr[17][x] = 0x7f
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}
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for x := 23; x < 32; x++ {
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d.ybr[17][x] = 0x7f
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}
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} else {
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for i := 0; i < 16; i++ {
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d.ybr[0][8+i] = d.img.Y[(16*mby-1)*d.img.YStride+16*mbx+i]
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}
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for i := 0; i < 8; i++ {
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d.ybr[17][8+i] = d.img.Cb[(8*mby-1)*d.img.CStride+8*mbx+i]
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}
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for i := 0; i < 8; i++ {
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d.ybr[17][24+i] = d.img.Cr[(8*mby-1)*d.img.CStride+8*mbx+i]
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}
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if mbx == d.mbw-1 {
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for i := 16; i < 20; i++ {
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d.ybr[0][8+i] = d.img.Y[(16*mby-1)*d.img.YStride+16*mbx+15]
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}
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} else {
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for i := 16; i < 20; i++ {
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d.ybr[0][8+i] = d.img.Y[(16*mby-1)*d.img.YStride+16*mbx+i]
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}
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}
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}
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for y := 4; y < 16; y += 4 {
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d.ybr[y][24] = d.ybr[0][24]
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d.ybr[y][25] = d.ybr[0][25]
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d.ybr[y][26] = d.ybr[0][26]
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d.ybr[y][27] = d.ybr[0][27]
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}
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}
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// btou converts a bool to a 0/1 value.
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func btou(b bool) uint8 {
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if b {
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return 1
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}
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return 0
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}
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// pack packs four 0/1 values into four bits of a uint32.
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func pack(x [4]uint8, shift int) uint32 {
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u := uint32(x[0])<<0 | uint32(x[1])<<1 | uint32(x[2])<<2 | uint32(x[3])<<3
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return u << uint(shift)
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}
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// unpack unpacks four 0/1 values from a four-bit value.
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var unpack = [16][4]uint8{
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{0, 0, 0, 0},
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{1, 0, 0, 0},
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{0, 1, 0, 0},
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{1, 1, 0, 0},
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{0, 0, 1, 0},
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{1, 0, 1, 0},
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{0, 1, 1, 0},
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{1, 1, 1, 0},
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{0, 0, 0, 1},
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{1, 0, 0, 1},
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{0, 1, 0, 1},
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{1, 1, 0, 1},
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{0, 0, 1, 1},
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{1, 0, 1, 1},
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{0, 1, 1, 1},
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{1, 1, 1, 1},
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}
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var (
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// The mapping from 4x4 region position to band is specified in section 13.3.
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bands = [17]uint8{0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 0}
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// Category probabilties are specified in section 13.2.
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// Decoding categories 1 and 2 are done inline.
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cat3456 = [4][12]uint8{
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{173, 148, 140, 0, 0, 0, 0, 0, 0, 0, 0, 0},
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{176, 155, 140, 135, 0, 0, 0, 0, 0, 0, 0, 0},
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{180, 157, 141, 134, 130, 0, 0, 0, 0, 0, 0, 0},
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{254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0},
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}
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// The zigzag order is:
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// 0 1 5 6
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// 2 4 7 12
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// 3 8 11 13
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// 9 10 14 15
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zigzag = [16]uint8{0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15}
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)
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// parseResiduals4 parses a 4x4 region of residual coefficients, as specified
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// in section 13.3, and returns a 0/1 value indicating whether there was at
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// least one non-zero coefficient.
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// r is the partition to read bits from.
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// plane and context describe which token probability table to use. context is
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// either 0, 1 or 2, and equals how many of the macroblock left and macroblock
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// above have non-zero coefficients.
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// quant are the DC/AC quantization factors.
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// skipFirstCoeff is whether the DC coefficient has already been parsed.
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// coeffBase is the base index of d.coeff to write to.
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func (d *Decoder) parseResiduals4(r *partition, plane int, context uint8, quant [2]uint16, skipFirstCoeff bool, coeffBase int) uint8 {
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prob, n := &d.tokenProb[plane], 0
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if skipFirstCoeff {
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n = 1
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}
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p := prob[bands[n]][context]
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if !r.readBit(p[0]) {
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return 0
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}
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for n != 16 {
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n++
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if !r.readBit(p[1]) {
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p = prob[bands[n]][0]
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continue
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}
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var v uint32
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if !r.readBit(p[2]) {
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v = 1
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p = prob[bands[n]][1]
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} else {
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if !r.readBit(p[3]) {
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if !r.readBit(p[4]) {
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v = 2
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} else {
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v = 3 + r.readUint(p[5], 1)
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}
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} else if !r.readBit(p[6]) {
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if !r.readBit(p[7]) {
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// Category 1.
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v = 5 + r.readUint(159, 1)
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} else {
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// Category 2.
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v = 7 + 2*r.readUint(165, 1) + r.readUint(145, 1)
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}
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} else {
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// Categories 3, 4, 5 or 6.
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b1 := r.readUint(p[8], 1)
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b0 := r.readUint(p[9+b1], 1)
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cat := 2*b1 + b0
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tab := &cat3456[cat]
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v = 0
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for i := 0; tab[i] != 0; i++ {
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v *= 2
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v += r.readUint(tab[i], 1)
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}
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v += 3 + (8 << cat)
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}
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p = prob[bands[n]][2]
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}
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z := zigzag[n-1]
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c := int32(v) * int32(quant[btou(z > 0)])
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if r.readBit(uniformProb) {
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c = -c
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}
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d.coeff[coeffBase+int(z)] = int16(c)
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if n == 16 || !r.readBit(p[0]) {
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return 1
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}
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}
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return 1
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}
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// parseResiduals parses the residuals and returns whether inner loop filtering
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// should be skipped for this macroblock.
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func (d *Decoder) parseResiduals(mbx, mby int) (skip bool) {
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partition := &d.op[mby&(d.nOP-1)]
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plane := planeY1SansY2
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quant := &d.quant[d.segment]
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// Parse the DC coefficient of each 4x4 luma region.
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if d.usePredY16 {
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nz := d.parseResiduals4(partition, planeY2, d.leftMB.nzY16+d.upMB[mbx].nzY16, quant.y2, false, whtCoeffBase)
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d.leftMB.nzY16 = nz
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d.upMB[mbx].nzY16 = nz
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d.inverseWHT16()
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plane = planeY1WithY2
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}
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var (
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nzDC, nzAC [4]uint8
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nzDCMask, nzACMask uint32
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coeffBase int
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)
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// Parse the luma coefficients.
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lnz := unpack[d.leftMB.nzMask&0x0f]
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unz := unpack[d.upMB[mbx].nzMask&0x0f]
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for y := 0; y < 4; y++ {
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nz := lnz[y]
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for x := 0; x < 4; x++ {
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nz = d.parseResiduals4(partition, plane, nz+unz[x], quant.y1, d.usePredY16, coeffBase)
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unz[x] = nz
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nzAC[x] = nz
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nzDC[x] = btou(d.coeff[coeffBase] != 0)
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coeffBase += 16
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}
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lnz[y] = nz
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nzDCMask |= pack(nzDC, y*4)
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nzACMask |= pack(nzAC, y*4)
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}
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lnzMask := pack(lnz, 0)
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unzMask := pack(unz, 0)
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// Parse the chroma coefficients.
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lnz = unpack[d.leftMB.nzMask>>4]
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unz = unpack[d.upMB[mbx].nzMask>>4]
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for c := 0; c < 4; c += 2 {
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for y := 0; y < 2; y++ {
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nz := lnz[y+c]
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for x := 0; x < 2; x++ {
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nz = d.parseResiduals4(partition, planeUV, nz+unz[x+c], quant.uv, false, coeffBase)
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unz[x+c] = nz
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nzAC[y*2+x] = nz
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nzDC[y*2+x] = btou(d.coeff[coeffBase] != 0)
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coeffBase += 16
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}
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lnz[y+c] = nz
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}
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nzDCMask |= pack(nzDC, 16+c*2)
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nzACMask |= pack(nzAC, 16+c*2)
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}
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lnzMask |= pack(lnz, 4)
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unzMask |= pack(unz, 4)
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// Save decoder state.
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d.leftMB.nzMask = uint8(lnzMask)
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d.upMB[mbx].nzMask = uint8(unzMask)
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d.nzDCMask = nzDCMask
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d.nzACMask = nzACMask
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// Section 15.1 of the spec says that "Steps 2 and 4 [of the loop filter]
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// are skipped... [if] there is no DCT coefficient coded for the whole
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// macroblock."
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return nzDCMask == 0 && nzACMask == 0
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}
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// reconstructMacroblock applies the predictor functions and adds the inverse-
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// DCT transformed residuals to recover the YCbCr data.
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func (d *Decoder) reconstructMacroblock(mbx, mby int) {
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if d.usePredY16 {
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p := checkTopLeftPred(mbx, mby, d.predY16)
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predFunc16[p](d, 1, 8)
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for j := 0; j < 4; j++ {
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for i := 0; i < 4; i++ {
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n := 4*j + i
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y := 4*j + 1
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x := 4*i + 8
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mask := uint32(1) << uint(n)
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if d.nzACMask&mask != 0 {
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d.inverseDCT4(y, x, 16*n)
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} else if d.nzDCMask&mask != 0 {
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d.inverseDCT4DCOnly(y, x, 16*n)
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}
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}
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}
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} else {
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for j := 0; j < 4; j++ {
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for i := 0; i < 4; i++ {
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n := 4*j + i
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y := 4*j + 1
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x := 4*i + 8
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predFunc4[d.predY4[j][i]](d, y, x)
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mask := uint32(1) << uint(n)
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if d.nzACMask&mask != 0 {
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d.inverseDCT4(y, x, 16*n)
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} else if d.nzDCMask&mask != 0 {
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d.inverseDCT4DCOnly(y, x, 16*n)
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}
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}
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}
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}
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p := checkTopLeftPred(mbx, mby, d.predC8)
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predFunc8[p](d, ybrBY, ybrBX)
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if d.nzACMask&0x0f0000 != 0 {
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d.inverseDCT8(ybrBY, ybrBX, bCoeffBase)
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} else if d.nzDCMask&0x0f0000 != 0 {
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d.inverseDCT8DCOnly(ybrBY, ybrBX, bCoeffBase)
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}
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predFunc8[p](d, ybrRY, ybrRX)
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if d.nzACMask&0xf00000 != 0 {
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d.inverseDCT8(ybrRY, ybrRX, rCoeffBase)
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} else if d.nzDCMask&0xf00000 != 0 {
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d.inverseDCT8DCOnly(ybrRY, ybrRX, rCoeffBase)
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}
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}
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// reconstruct reconstructs one macroblock and returns whether inner loop
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// filtering should be skipped for it.
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func (d *Decoder) reconstruct(mbx, mby int) (skip bool) {
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if d.segmentHeader.updateMap {
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if !d.fp.readBit(d.segmentHeader.prob[0]) {
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d.segment = int(d.fp.readUint(d.segmentHeader.prob[1], 1))
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} else {
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d.segment = int(d.fp.readUint(d.segmentHeader.prob[2], 1)) + 2
|
|
}
|
|
}
|
|
if d.useSkipProb {
|
|
skip = d.fp.readBit(d.skipProb)
|
|
}
|
|
// Prepare the workspace.
|
|
for i := range d.coeff {
|
|
d.coeff[i] = 0
|
|
}
|
|
d.prepareYBR(mbx, mby)
|
|
// Parse the predictor modes.
|
|
d.usePredY16 = d.fp.readBit(145)
|
|
if d.usePredY16 {
|
|
d.parsePredModeY16(mbx)
|
|
} else {
|
|
d.parsePredModeY4(mbx)
|
|
}
|
|
d.parsePredModeC8()
|
|
// Parse the residuals.
|
|
if !skip {
|
|
skip = d.parseResiduals(mbx, mby)
|
|
} else {
|
|
if d.usePredY16 {
|
|
d.leftMB.nzY16 = 0
|
|
d.upMB[mbx].nzY16 = 0
|
|
}
|
|
d.leftMB.nzMask = 0
|
|
d.upMB[mbx].nzMask = 0
|
|
d.nzDCMask = 0
|
|
d.nzACMask = 0
|
|
}
|
|
// Reconstruct the YCbCr data and copy it to the image.
|
|
d.reconstructMacroblock(mbx, mby)
|
|
for i, y := (mby*d.img.YStride+mbx)*16, 0; y < 16; i, y = i+d.img.YStride, y+1 {
|
|
copy(d.img.Y[i:i+16], d.ybr[ybrYY+y][ybrYX:ybrYX+16])
|
|
}
|
|
for i, y := (mby*d.img.CStride+mbx)*8, 0; y < 8; i, y = i+d.img.CStride, y+1 {
|
|
copy(d.img.Cb[i:i+8], d.ybr[ybrBY+y][ybrBX:ybrBX+8])
|
|
copy(d.img.Cr[i:i+8], d.ybr[ybrRY+y][ybrRX:ybrRX+8])
|
|
}
|
|
return skip
|
|
}
|