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Merge pull request #4950 from fkaelberer/fasterJPEGtransform

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Faster JPEG transform
This commit is contained in:
Yury Delendik 2014-06-17 09:03:23 -05:00
commit bad24bf707
1 changed files with 133 additions and 111 deletions
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244
src/core/jpg.js
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@ -32,7 +32,7 @@ version was created by github user notmasteryet
'use strict';
var JpegImage = (function jpegImage() {
var dctZigZag = new Int32Array([
var dctZigZag = new Uint8Array([
0,
1, 8,
16, 9, 2,
@ -99,10 +99,8 @@ var JpegImage = (function jpegImage() {
return 64 * ((component.blocksPerLine + 1) * row + col);
}
function decodeScan(data, offset,
frame, components, resetInterval,
spectralStart, spectralEnd,
successivePrev, successive) {
function decodeScan(data, offset, frame, components, resetInterval,
spectralStart, spectralEnd, successivePrev, successive) {
var precision = frame.precision;
var samplesPerLine = frame.samplesPerLine;
var scanLines = frame.scanLines;
@ -386,166 +384,190 @@ var JpegImage = (function jpegImage() {
// IEEE Intl. Conf. on Acoustics, Speech & Signal Processing, 1989,
// 988-991.
function quantizeAndInverse(component, blockBufferOffset, p) {
var qt = component.quantizationTable;
var v0, v1, v2, v3, v4, v5, v6, v7, t;
var i;
// dequant
for (i = 0; i < 64; i++) {
p[i] = component.blockData[blockBufferOffset + i] * qt[i];
}
var qt = component.quantizationTable, blockData = component.blockData;
var v0, v1, v2, v3, v4, v5, v6, v7;
var p0, p1, p2, p3, p4, p5, p6, p7;
var t;
// inverse DCT on rows
for (i = 0; i < 8; ++i) {
var row = 8 * i;
for (var row = 0; row < 64; row += 8) {
// gather block data
p0 = blockData[blockBufferOffset + row];
p1 = blockData[blockBufferOffset + row + 1];
p2 = blockData[blockBufferOffset + row + 2];
p3 = blockData[blockBufferOffset + row + 3];
p4 = blockData[blockBufferOffset + row + 4];
p5 = blockData[blockBufferOffset + row + 5];
p6 = blockData[blockBufferOffset + row + 6];
p7 = blockData[blockBufferOffset + row + 7];
// dequant p0
p0 *= qt[row];
// check for all-zero AC coefficients
if (p[1 + row] === 0 && p[2 + row] === 0 && p[3 + row] === 0 &&
p[4 + row] === 0 && p[5 + row] === 0 && p[6 + row] === 0 &&
p[7 + row] === 0) {
t = (dctSqrt2 * p[0 + row] + 512) >> 10;
p[0 + row] = t;
p[1 + row] = t;
p[2 + row] = t;
p[3 + row] = t;
p[4 + row] = t;
p[5 + row] = t;
p[6 + row] = t;
p[7 + row] = t;
if ((p1 | p2 | p3 | p4 | p5 | p6 | p7) === 0) {
t = (dctSqrt2 * p0 + 512) >> 10;
p[row] = t;
p[row + 1] = t;
p[row + 2] = t;
p[row + 3] = t;
p[row + 4] = t;
p[row + 5] = t;
p[row + 6] = t;
p[row + 7] = t;
continue;
}
// dequant p1 ... p7
p1 *= qt[row + 1];
p2 *= qt[row + 2];
p3 *= qt[row + 3];
p4 *= qt[row + 4];
p5 *= qt[row + 5];
p6 *= qt[row + 6];
p7 *= qt[row + 7];
// stage 4
v0 = (dctSqrt2 * p[0 + row] + 128) >> 8;
v1 = (dctSqrt2 * p[4 + row] + 128) >> 8;
v2 = p[2 + row];
v3 = p[6 + row];
v4 = (dctSqrt1d2 * (p[1 + row] - p[7 + row]) + 128) >> 8;
v7 = (dctSqrt1d2 * (p[1 + row] + p[7 + row]) + 128) >> 8;
v5 = p[3 + row] << 4;
v6 = p[5 + row] << 4;
v0 = (dctSqrt2 * p0 + 128) >> 8;
v1 = (dctSqrt2 * p4 + 128) >> 8;
v2 = p2;
v3 = p6;
v4 = (dctSqrt1d2 * (p1 - p7) + 128) >> 8;
v7 = (dctSqrt1d2 * (p1 + p7) + 128) >> 8;
v5 = p3 << 4;
v6 = p5 << 4;
// stage 3
t = (v0 - v1+ 1) >> 1;
v0 = (v0 + v1 + 1) >> 1;
v1 = t;
t = (v2 * dctSin6 + v3 * dctCos6 + 128) >> 8;
v1 = v0 - v1;
t = (v2 * dctSin6 + v3 * dctCos6 + 128) >> 8;
v2 = (v2 * dctCos6 - v3 * dctSin6 + 128) >> 8;
v3 = t;
t = (v4 - v6 + 1) >> 1;
v4 = (v4 + v6 + 1) >> 1;
v6 = t;
t = (v7 + v5 + 1) >> 1;
v5 = (v7 - v5 + 1) >> 1;
v7 = t;
v6 = v4 - v6;
v7 = (v7 + v5 + 1) >> 1;
v5 = v7 - v5;
// stage 2
t = (v0 - v3 + 1) >> 1;
v0 = (v0 + v3 + 1) >> 1;
v3 = t;
t = (v1 - v2 + 1) >> 1;
v3 = v0 - v3;
v1 = (v1 + v2 + 1) >> 1;
v2 = t;
t = (v4 * dctSin3 + v7 * dctCos3 + 2048) >> 12;
v2 = v1 - v2;
t = (v4 * dctSin3 + v7 * dctCos3 + 2048) >> 12;
v4 = (v4 * dctCos3 - v7 * dctSin3 + 2048) >> 12;
v7 = t;
t = (v5 * dctSin1 + v6 * dctCos1 + 2048) >> 12;
t = (v5 * dctSin1 + v6 * dctCos1 + 2048) >> 12;
v5 = (v5 * dctCos1 - v6 * dctSin1 + 2048) >> 12;
v6 = t;
// stage 1
p[0 + row] = v0 + v7;
p[7 + row] = v0 - v7;
p[1 + row] = v1 + v6;
p[6 + row] = v1 - v6;
p[2 + row] = v2 + v5;
p[5 + row] = v2 - v5;
p[3 + row] = v3 + v4;
p[4 + row] = v3 - v4;
p[row] = v0 + v7;
p[row + 7] = v0 - v7;
p[row + 1] = v1 + v6;
p[row + 6] = v1 - v6;
p[row + 2] = v2 + v5;
p[row + 5] = v2 - v5;
p[row + 3] = v3 + v4;
p[row + 4] = v3 - v4;
}
// inverse DCT on columns
for (i = 0; i < 8; ++i) {
var col = i;
for (var col = 0; col < 8; ++col) {
p0 = p[col];
p1 = p[col + 8];
p2 = p[col + 16];
p3 = p[col + 24];
p4 = p[col + 32];
p5 = p[col + 40];
p6 = p[col + 48];
p7 = p[col + 56];
// check for all-zero AC coefficients
if (p[1*8 + col] === 0 && p[2*8 + col] === 0 && p[3*8 + col] === 0 &&
p[4*8 + col] === 0 && p[5*8 + col] === 0 && p[6*8 + col] === 0 &&
p[7*8 + col] === 0) {
t = (dctSqrt2 * p[i+0] + 8192) >> 14;
p[0*8 + col] = t;
p[1*8 + col] = t;
p[2*8 + col] = t;
p[3*8 + col] = t;
p[4*8 + col] = t;
p[5*8 + col] = t;
p[6*8 + col] = t;
p[7*8 + col] = t;
if ((p1 | p2 | p3 | p4 | p5 | p6 | p7) === 0) {
t = (dctSqrt2 * p0 + 8192) >> 14;
// convert to 8 bit
t = (t < -2040) ? 0 : (t >= 2024) ? 255 : (t + 2056) >> 4;
blockData[blockBufferOffset + col] = t;
blockData[blockBufferOffset + col + 8] = t;
blockData[blockBufferOffset + col + 16] = t;
blockData[blockBufferOffset + col + 24] = t;
blockData[blockBufferOffset + col + 32] = t;
blockData[blockBufferOffset + col + 40] = t;
blockData[blockBufferOffset + col + 48] = t;
blockData[blockBufferOffset + col + 56] = t;
continue;
}
// stage 4
v0 = (dctSqrt2 * p[0*8 + col] + 2048) >> 12;
v1 = (dctSqrt2 * p[4*8 + col] + 2048) >> 12;
v2 = p[2*8 + col];
v3 = p[6*8 + col];
v4 = (dctSqrt1d2 * (p[1*8 + col] - p[7*8 + col]) + 2048) >> 12;
v7 = (dctSqrt1d2 * (p[1*8 + col] + p[7*8 + col]) + 2048) >> 12;
v5 = p[3*8 + col];
v6 = p[5*8 + col];
v0 = (dctSqrt2 * p0 + 2048) >> 12;
v1 = (dctSqrt2 * p4 + 2048) >> 12;
v2 = p2;
v3 = p6;
v4 = (dctSqrt1d2 * (p1 - p7) + 2048) >> 12;
v7 = (dctSqrt1d2 * (p1 + p7) + 2048) >> 12;
v5 = p3;
v6 = p5;
// stage 3
t = (v0 - v1 + 1) >> 1;
v0 = (v0 + v1 + 1) >> 1;
v1 = t;
t = (v2 * dctSin6 + v3 * dctCos6 + 2048) >> 12;
// Shift v0 by 128.5 << 5 here, so we don't need to shift p0...p7 when
// converting to UInt8 range later.
v0 = ((v0 + v1 + 1) >> 1) + 4112;
v1 = v0 - v1;
t = (v2 * dctSin6 + v3 * dctCos6 + 2048) >> 12;
v2 = (v2 * dctCos6 - v3 * dctSin6 + 2048) >> 12;
v3 = t;
t = (v4 - v6 + 1) >> 1;
v4 = (v4 + v6 + 1) >> 1;
v6 = t;
t = (v7 + v5 + 1) >> 1;
v5 = (v7 - v5 + 1) >> 1;
v7 = t;
v6 = v4 - v6;
v7 = (v7 + v5 + 1) >> 1;
v5 = v7 - v5;
// stage 2
t = (v0 - v3 + 1) >> 1;
v0 = (v0 + v3 + 1) >> 1;
v3 = t;
t = (v1 - v2 + 1) >> 1;
v3 = v0 - v3;
v1 = (v1 + v2 + 1) >> 1;
v2 = t;
t = (v4 * dctSin3 + v7 * dctCos3 + 2048) >> 12;
v2 = v1 - v2;
t = (v4 * dctSin3 + v7 * dctCos3 + 2048) >> 12;
v4 = (v4 * dctCos3 - v7 * dctSin3 + 2048) >> 12;
v7 = t;
t = (v5 * dctSin1 + v6 * dctCos1 + 2048) >> 12;
t = (v5 * dctSin1 + v6 * dctCos1 + 2048) >> 12;
v5 = (v5 * dctCos1 - v6 * dctSin1 + 2048) >> 12;
v6 = t;
// stage 1
p[0*8 + col] = v0 + v7;
p[7*8 + col] = v0 - v7;
p[1*8 + col] = v1 + v6;
p[6*8 + col] = v1 - v6;
p[2*8 + col] = v2 + v5;
p[5*8 + col] = v2 - v5;
p[3*8 + col] = v3 + v4;
p[4*8 + col] = v3 - v4;
}
p0 = v0 + v7;
p7 = v0 - v7;
p1 = v1 + v6;
p6 = v1 - v6;
p2 = v2 + v5;
p5 = v2 - v5;
p3 = v3 + v4;
p4 = v3 - v4;
// convert to 8-bit integers
for (i = 0; i < 64; ++i) {
var index = blockBufferOffset + i;
var q = p[i];
q = (q <= -2056) ? 0 : (q >= 2024) ? 255 : (q + 2056) >> 4;
component.blockData[index] = q;
// convert to 8-bit integers
p0 = (p0 < 16) ? 0 : (p0 >= 4080) ? 255 : p0 >> 4;
p1 = (p1 < 16) ? 0 : (p1 >= 4080) ? 255 : p1 >> 4;
p2 = (p2 < 16) ? 0 : (p2 >= 4080) ? 255 : p2 >> 4;
p3 = (p3 < 16) ? 0 : (p3 >= 4080) ? 255 : p3 >> 4;
p4 = (p4 < 16) ? 0 : (p4 >= 4080) ? 255 : p4 >> 4;
p5 = (p5 < 16) ? 0 : (p5 >= 4080) ? 255 : p5 >> 4;
p6 = (p6 < 16) ? 0 : (p6 >= 4080) ? 255 : p6 >> 4;
p7 = (p7 < 16) ? 0 : (p7 >= 4080) ? 255 : p7 >> 4;
// store block data
blockData[blockBufferOffset + col] = p0;
blockData[blockBufferOffset + col + 8] = p1;
blockData[blockBufferOffset + col + 16] = p2;
blockData[blockBufferOffset + col + 24] = p3;
blockData[blockBufferOffset + col + 32] = p4;
blockData[blockBufferOffset + col + 40] = p5;
blockData[blockBufferOffset + col + 48] = p6;
blockData[blockBufferOffset + col + 56] = p7;
}
}
function buildComponentData(frame, component) {
var blocksPerLine = component.blocksPerLine;
var blocksPerColumn = component.blocksPerColumn;
var computationBuffer = new Int32Array(64);
var computationBuffer = new Int16Array(64);
for (var blockRow = 0; blockRow < blocksPerColumn; blockRow++) {
for (var blockCol = 0; blockCol < blocksPerLine; blockCol++) {
@ -670,7 +692,7 @@ var JpegImage = (function jpegImage() {
var z;
while (offset < quantizationTablesEnd) {
var quantizationTableSpec = data[offset++];
var tableData = new Int32Array(64);
var tableData = new Uint16Array(64);
if ((quantizationTableSpec >> 4) === 0) { // 8 bit values
for (j = 0; j < 64; j++) {
z = dctZigZag[j];