ref: e0f46e9a44dec8725438a23708679494c315e2b6
dir: /js/h264bsd.js/
//
// Copyright (c) 2013 Sam Leitch. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//
/*
* This class wraps the details of the h264bsd library.
* Module object is an Emscripten module provided globally by h264bsd_asm.js
* targetElement element is an HTML element that will emit events that should
* be listened for when H264 images are ready to be displayed
* forceRGB boolean Says whether the YUV->RGB decoding should be used (even
* in the presence of the WebGL canvas)
*/
function H264Decoder(Module, targetElement, forceRGB) {
var self = this;
self.Module = Module;
self.released = false;
self.yuvCanvas = null;
self.pStorage = H264Decoder.h264bsdAlloc_(self.Module);
H264Decoder.h264bsdInit_(self.Module, self.pStorage, 0);
self.targetElement = targetElement;
//If we are using RGB
if (forceRGB){
self.useWebGL = false;
self.precision = 32768;
//Calculate all of the YUV->RGB coefficients
self.co_y = Math.floor((1.164 * self.precision) + 0.5);
self.co_rv = Math.floor((1.596 * self.precision) + 0.5);
self.co_gu = Math.floor((0.391 * self.precision) + 0.5);
self.co_gv = Math.floor((0.813 * self.precision) + 0.5);
self.co_bu = Math.floor((2.018 * self.precision) + 0.5);
self.coefficients_y = [];
for(var i = 0; i < 256; i++)
{
self.coefficients_y[i] = self.co_y * (i - 16) + (self.precision / 2);
}
self.coefficients_rv = [];
for(var i = 0; i < 256; i++)
{
self.coefficients_rv[i] = self.co_rv * (i - 128);
}
self.coefficients_gu = [];
for(var i = 0; i < 256; i++)
{
self.coefficients_gu[i] = self.co_gu * (i - 128);
}
self.coefficients_gv = [];
for(var i = 0; i < 256; i++)
{
self.coefficients_gv[i] = self.co_gv * (i - 128);
}
self.coefficients_bu = [];
for(var i = 0; i < 256; i++)
{
self.coefficients_bu[i] = self.co_bu * (i - 128);
}
}else{
//Check if we can use WebGL (as this dictates the output pipline)
self.useWebGL = H264Decoder.detectWebGl_();
}
};
H264Decoder.RDY = 0;
H264Decoder.PIC_RDY = 1;
H264Decoder.HDRS_RDY = 2;
H264Decoder.ERROR = 3;
H264Decoder.PARAM_SET_ERROR = 4;
H264Decoder.MEMALLOC_ERROR = 5;
//Clean up memory used by the decoder
H264Decoder.prototype.release = function() {
var self = this;
if(self.released) return;
self.released = true;
H264Decoder.h264bsdShutdown_(self.Module, self.pStorage);
H264Decoder.h264bsdFree_(self.Module, self.pStorage);
};
//Takes an array buffer of bytes and returns a UInt8Array of the decoded bytes
H264Decoder.prototype.decode = function(data) {
var self = this;
if(typeof data === 'undefined' || !(data instanceof ArrayBuffer)) {
throw new Error("data must be a ArrayBuffer instance")
}
data = new Uint8Array(data);
var pData = 0; //The offset into the heap when decoding
var pAlloced = 0; //The original pointer to the data buffer (for freeing)
var pBytesRead = 0; //Pointer to bytesRead
var length = data.byteLength; //The byte-wise length of the data to decode
var bytesRead = 0; //The number of bytes read from a decode operation
var retCode = 0; //Return code from a decode operation
var lastPicId = 0; //ID of the last picture decoded
//Get a pointer into the heap were our decoded bytes will live
pData = pAlloced = H264Decoder.malloc_(self.Module, length);
self.Module.HEAPU8.set(data, pData);
//get a pointer to where bytesRead will be stored: Uint32 = 4 bytes
pBytesRead = H264Decoder.malloc_(self.Module, 4);
//Keep decoding frames while there is still something to decode
while(length > 0) {
retCode = H264Decoder.h264bsdDecode_(self.Module, self.pStorage, pData, length, lastPicId, pBytesRead);
bytesRead = self.Module.getValue(pBytesRead, 'i32');
switch(retCode){
case H264Decoder.PIC_RDY:
lastPicId++;
var evt = new CustomEvent("pictureReady", {
detail: self.getNextOutputPicture()
});
if (self.targetElement != null){
//Raise the event on the displaying canvas element
self.targetElement.dispatchEvent(evt);
}
break;
}
length = length - bytesRead;
pData = pData + bytesRead;
}
if(pAlloced != 0) {
H264Decoder.free_(self.Module, pAlloced);
}
if(pBytesRead != 0) {
H264Decoder.free_(self.Module, pBytesRead);
}
};
H264Decoder.prototype.getNextOutputPicture = function(){
var self = this;
var length = H264Decoder.getYUVLength_(self.Module, self.pStorage);
var pPicId = H264Decoder.malloc_(self.Module, 4);
var picId = 0;
var pIsIdrPic = H264Decoder.malloc_(self.Module, 4);
var isIdrPic = 0;
var pNumErrMbs = H264Decoder.malloc_(self.Module, 4);
var numErrMbs = 0;
var pBytes = H264Decoder.h264bsdNextOutputPicture_(self.Module, self.pStorage, pPicId, pIsIdrPic, pNumErrMbs);
var bytes = null;
//We don't really use these
picId = self.Module.getValue(pPicId, 'i32');
isIdrPic = self.Module.getValue(pIsIdrPic, 'i32');
numErrMbs = self.Module.getValue(pNumErrMbs, 'i32');
bytes = self.Module.HEAPU8.subarray(pBytes, (pBytes + length));
H264Decoder.free_(self.Module, pPicId);
H264Decoder.free_(self.Module, pIsIdrPic);
H264Decoder.free_(self.Module, pNumErrMbs);
var ret = {};
var croppingInfo = H264Decoder.getCroppingInfo_(self.Module, self.pStorage);
//Return bytes according to the requested format
if (self.useWebGL){
ret = {
encoding: 'YUV',
picture: bytes,
height: croppingInfo.height,
width: croppingInfo.width};
}else{
ret = {
encoding: 'RGB',
picture: H264Decoder.convertYUV2RGB_(bytes, croppingInfo, self),
height: croppingInfo.height,
width: croppingInfo.width};
}
return ret;
};
H264Decoder.getCroppingInfo_ = function(Module, pStorage){
var self = this;
var result = {
'width': (H264Decoder.h264bsdPicWidth_(Module, pStorage)*16),
'height': (H264Decoder.h264bsdPicHeight_(Module, pStorage)*16),
'top': 0,
'left': 0
};
return result;
};
H264Decoder.getYUVLength_ = function(Module, pStorage){
var width = H264Decoder.h264bsdPicWidth_(Module, pStorage);
var height = H264Decoder.h264bsdPicHeight_(Module, pStorage);
return (width * 16 * height * 16) + (2 * width * 16 * height * 8);
};
//http://www.browserleaks.com/webgl#howto-detect-webgl
H264Decoder.detectWebGl_ = function()
{
if (!!window.WebGLRenderingContext) {
var canvas = document.createElement("canvas"),
names = ["webgl", "experimental-webgl", "moz-webgl", "webkit-3d"],
context = false;
for(var i=0;i<4;i++) {
try {
context = canvas.getContext(names[i]);
if (context && typeof context.getParameter == "function") {
// WebGL is enabled
return true;
}
} catch(e) {}
}
// WebGL is supported, but disabled
return false;
}
// WebGL not supported
return false;
};
//If WebGL Canvas is not availble, this will convert an array of yuv bytes into an array of rgb bytes
H264Decoder.convertYUV2RGB_ = function(yuvBytes, croppingInfo, exCtx){
var width = croppingInfo.width - croppingInfo.left;
var height = croppingInfo.height - croppingInfo.top;
var rgbBytes = new Uint8ClampedArray(4 * height * width);
var lumaSize = width * height;
var chromaSize = lumaSize >> 2;
var planeY_off = 0;
var planeU_off = lumaSize;
var planeV_off = lumaSize + chromaSize;
var stride_Y_h_off;
var stride_UV_h_off;
var stride_RGBA_off;
for (var h=0;h<height;h++) {
stride_Y_h_off = (width)*h;
stride_UV_h_off = (width>>1)*(h>>1);
stride_RGBA_off = (width<<2)*h;
for (var w=0; w<width; w++) {
var Y = yuvBytes[planeY_off+ w+stride_Y_h_off];
stride_UV_off = (w>>1)+stride_UV_h_off;
var U = (yuvBytes[planeU_off+ stride_UV_off]);
var V = (yuvBytes[planeV_off+ stride_UV_off]);
var R = exCtx.coefficients_y[Y] + exCtx.coefficients_rv[V];
var G = exCtx.coefficients_y[Y] - exCtx.coefficients_gu[U] - exCtx.coefficients_gv[V];
var B = exCtx.coefficients_y[Y] + exCtx.coefficients_bu[U];
R = R >> 15; // div by 32768
G = G >> 15;
B = B >> 15;
var outputData_pos = (w<<2)+stride_RGBA_off;
rgbBytes[0+outputData_pos] = R;
rgbBytes[1+outputData_pos] = G;
rgbBytes[2+outputData_pos] = B;
rgbBytes[3+outputData_pos] = 255;
}
}
return rgbBytes;
};
// u32 h264bsdDecode(storage_t *pStorage, u8 *byteStrm, u32 len, u32 picId, u32 *readBytes);
H264Decoder.h264bsdDecode_ = function(Module, pStorage, pBytes, len, picId, pBytesRead) {
return Module.ccall('h264bsdDecode', Number,
[Number, Number, Number, Number, Number],
[pStorage, pBytes, len, picId, pBytesRead]);
};
// storage_t* h264bsdAlloc();
H264Decoder.h264bsdAlloc_ = function(Module) {
return Module.ccall('h264bsdAlloc', Number);
};
// void h264bsdFree(storage_t *pStorage);
H264Decoder.h264bsdFree_ = function(Module, pStorage) {
Module.ccall('h264bsdFree', null, [Number], [pStorage]);
};
// u32 h264bsdInit(storage_t *pStorage, u32 noOutputReordering);
H264Decoder.h264bsdInit_ = function(Module, pStorage, noOutputReordering) {
return Module.ccall('h264bsdInit', Number, [Number, Number], [pStorage, noOutputReordering]);
};
//void h264bsdShutdown(storage_t *pStorage);
H264Decoder.h264bsdShutdown_ = function(Module, pStorage) {
Module.ccall('h264bsdShutdown', null, [Number], [pStorage]);
};
// u8* h264bsdNextOutputPicture(storage_t *pStorage, u32 *picId, u32 *isIdrPic, u32 *numErrMbs);
H264Decoder.h264bsdNextOutputPicture_ = function(Module, pStorage, pPicId, pIsIdrPic, pNumErrMbs) {
return Module.ccall('h264bsdNextOutputPicture',
Number,
[Number, Number, Number, Number],
[pStorage, pPicId, pIsIdrPic, pNumErrMbs]);
};
// u32 h264bsdPicWidth(storage_t *pStorage);
H264Decoder.h264bsdPicWidth_ = function(Module, pStorage) {
return Module.ccall('h264bsdPicWidth', Number, [Number], [pStorage]);
};
// u32 h264bsdPicHeight(storage_t *pStorage);
H264Decoder.h264bsdPicHeight_ = function(Module, pStorage) {
return Module.ccall('h264bsdPicHeight', Number, [Number], [pStorage]);
};
// void h264bsdCroppingParams(storage_t *pStorage, u32 *croppingFlag, u32 *left, u32 *width, u32 *top, u32 *height);
H264Decoder.h264bsdCroppingParams_ = function(Module, pStorage, pCroppingFlag, pLeft, pWidth, pTop, pHeight) {
return Module.ccall('h264bsdCroppingParams',
Number,
[Number, Number, Number, Number, Number, Number, Number],
[pStorage, pCroppingFlag, pLeft, pWidth, pTop, pHeight]);
};
// u32 h264bsdCheckValidParamSets(storage_t *pStorage);
H264Decoder.h264bsdCheckValidParamSets_ = function(Module, pStorage){
return Module.ccall('h264bsdCheckValidParamSets', Number, [Number], [pStorage]);
};
// void* malloc(size_t size);
H264Decoder.malloc_ = function(Module, size){
return Module.ccall('malloc', Number, [Number], [size]);
};
// void free(void* ptr);
H264Decoder.free_ = function(Module, ptr){
return Module.ccall('free', null, [Number], [ptr]);
};
// void* memcpy(void* dest, void* src, size_t size);
H264Decoder.memcpy_ = function(Module, length){
return Module.ccall('malloc', Number, [Number, Number, Number], [dest, src, size]);
};