基于WebAssembly无插件解码H264/H265码流播放器

基于WebAssembly无插件解码H264/H265码流播放器
之前看到一篇文章：web无插件解码播放H264/H265(WebAssembly解码HTML5播放)
H.265/HEVC在Web视频播放的实践

一.emsdk工具的安装

https://www.cnblogs.com/tonghaolang/p/9253719.html Windows下安装enscripten
Windows 和Linux 安装 emsdk
https://blog.csdn.net/qq_34754747/article/details/103815349?depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-11&utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromBaidu-11
安装emsdk工具
wget https://s3.amazonaws.com/mozilla-games/emscripten/releases/emsdk-portable.tar.gz

二.emsdk编译ffmpeg

下载ffmpeg源码,用下面命令在linux平台编译得到ffmpeg静态库文件。

 emconfigure ./configure --cc="emcc" --prefix=/opt/tar-download/emccffmpeg \
 --enable-cross-compile --target-os=none --arch=x86_32 --cpu=generic --disable-ffplay --disable-ffprobe \
 --disable-asm --disable-doc --disable-devices --disable-pthreads --disable-w32threads --disable-network \
 --disable-hwaccels --disable-parsers --disable-bsfs --disable-debug --disable-protocols --disable-indevs \
 --disable-outdevs --enable-protocol=file --enable-decoder=hevc --enable-decoder=h264

三.ffmpeg解码库

ffmpeg.h

#ifndef _FFMPEG_H_
#define _FFMPEG_H_

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>

#include "libswscale/swscale.h"
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "libavcodec/avcodec.h"

#define QUEUE_SIZE	20

//图片数据
typedef struct _imgdata{
	int width;
	int height;
	uint8_t* data;
}Imgdata;


//解码API
extern int init_decoder(int codeid);	//初始化解码器

extern Imgdata* decoder_raw(char* framedata, int framesize );	//解码

extern uint8_t* process(AVFrame* frame, uint8_t* buff);	//yuvdata 保存在buff中

extern void free_decoder();	//关闭解码器

#endif

ffmpeg.c

#include "ffmpeg.h"

AVCodec* codec;                 //记录编码详细信息
AVCodecParserContext* parser = NULL;
AVCodecContext* c = NULL;       //记录码流编码信息
AVPacket* pkt = NULL;                  
AVFrame* frame = NULL;          //存储视频中的帧
Imgdata *imgbuff = NULL;
static int codeId = 0;

/**********************************************************
 *	功能: 初始化解码器
 *	参数: codeid---> 1=打开h.265解码器
 *					 0=打开h.264解码器
 *
 *  返回值：0=成功初始化
 *		    -1=初始化失败
 *
 * *******************************************************/

int init_decoder(int codeid)
{
	codeId = codeid;
	switch(codeid)
	{
		case 0:{
			codec = avcodec_find_decoder(AV_CODEC_ID_H264);
			break;
		}
		case 1:{
			codec = avcodec_find_decoder(AV_CODEC_ID_H265);
            break;
		}
		default:{
			printf("In C language no choose h.264/h.265 decoder\n");
			return -1;
		}
	}

	if(NULL == codec)
	{
		printf("codec find decoder failed\n");
        return -1;
	}

	parser = av_parser_init(codec->id);
	if(NULL == parser)
	{
		printf("can't jsparser init!\n");
        return -1;
	} 

	c = avcodec_alloc_context3(codec);
    if(NULL == c)
    {
        printf("can't allocate video jscodec context!\n");
        return -1;
    }

    if(avcodec_open2(c, codec, NULL) < 0)
    {
        printf("can't open codec\n");
        return -1;
    }

    frame = av_frame_alloc();
    if(NULL == frame)
    {
        printf("can't allocate video frame\n");
        return -1;
    }

    pkt = av_packet_alloc();
    if(NULL == pkt)
    {
        printf("can't allocate video packet\n");
        return -1;
    }

    imgbuff = (Imgdata*)malloc(sizeof(Imgdata));
    if(NULL == imgbuff)
    {
    	printf("malloc imgbuff failed\n");
    	return -1;
    }
	
    printf("In C language init decoder success!\n");
    return 0;
}

/**********************************************************
 *	功能: 解码，将h.265/h.264裸流解码为yuv420p数据
 *  参数: framedata---->裸流数据
 *        framesize---->裸流长度
 *
 *  返回值:Imgdata的结构体 Imgdata->width  视频宽度
 *						   Imgdata->height 视频高度
 *						   Imgdata->data   yuv420p数据
 *
 * *******************************************************/
Imgdata* decoder_raw(char* framedata, int framesize )
{
	if(NULL == framedata || framesize <= 0)
	{
		printf("In C language framedata is null or framesize is zero\n");
		return NULL;
	}
	/*****************************************************
	 *	过滤，第一次检测首帧是否是VPS/SPS，若不是跳过不解码
		第一次检测到首帧是VPS/SPS，后面不用检测，flag=0 --> flag=1
	 *
	 * **************************************************/
	int nut = 0;
	static int flag = 0;
	if(codeId == 0)	//裸流h.264
	{
		nut = (char)framedata[4]& 0x1f;
		while(!flag)
		{
			if( 7==nut ){	//PPS
				flag = 1;
				break;
			}
			else if( 8==nut )//PPS
			{
				return NULL;
			}
			else if( 5==nut )//I
			{
				return NULL;
			}
			else if( 1==nut )//P
			{
				return NULL;
			}
			else if( 9==nut )//AUD
			{
				return NULL;
			}
			else if( 6==nut )//SEI
			{
				return NULL;
			}
			else//Unknown
			{
				return NULL;
			}
		}
	}
	else 
	{
		//h.265裸流
		nut = (char)(framedata[4]>>1) &0x3f;
		while(!flag)
		{
			if(nut == 32)//VPS	
			{
				flag = 1;
				break;
			}
			else if(nut == 33)//SPS
			{
				return NULL;
			}
			else if(nut == 34)//PPS
			{
				return NULL;
			}
			else if(nut == 19)//I帧
			{
				return NULL;
			}
			else if(nut == 1)//P帧
			{
				return NULL;
			}
			else if(nut == 35)//AUD
			{
				return NULL;
			}
			else if(nut == 39)//SEI
			{
				return NULL;
			}
			else			  //Unknown	
			{
				return NULL;
			}
		}
	
	}
	
	//开始解码
	int ret = 0;
	int size = 0;
	while(framesize > 0)
	{
		size = av_parser_parse2(parser, c, &pkt->data, &pkt->size, (const uint8_t *)framedata, framesize, 
						AV_NOPTS_VALUE, AV_NOPTS_VALUE, AV_NOPTS_VALUE);
        if(size < 0)
        {
            printf("Error while parsing\n");
            return NULL;
        }
        framedata   += size;
        framesize   -= size;
        if(pkt->size)
        {
        	ret = avcodec_send_packet(c, pkt);
    		if (ret < 0) 
    		{
        		printf("In C language error sending a packet for decoding\n");
        		return NULL;
    		}
    		else
    		{
    			while(ret >=0 )
    			{
    				
    				ret = avcodec_receive_frame(c, frame);
    				if(ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
    				{
    					break;
    				}
    				else if(ret < 0)
    				{
    					printf("Error during decoding\n");
    					return NULL;
    				}

    				//yuv数据处理，保存在buff中,在网页中调用yuv420p数据交给webgl渲染
		            int yuvBytes = av_image_get_buffer_size(AV_PIX_FMT_YUV420P, frame->width, frame->height, 1);
		            uint8_t *buff = (uint8_t*)malloc(yuvBytes);
		            if(buff == NULL)
		            {
		                printf("malloc yuvBytes failed!\n");
		                return NULL;
		            }
		            
		            imgbuff->width = frame->width;
		            imgbuff->height = frame->height;
		            imgbuff->data = process(frame, buff);
		            free(buff); 
    			}
    		}
        }
	}
	return imgbuff;
}

/******************************************************
 *	功能: 将一帧yuvdata 保存为yuv buff
 *  参数: frame---->yuvframe
 *        buff----->保存数据buff
 *
 *  返回值: buff yuv420p数据
 * ***************************************************/

uint8_t* process(AVFrame* frame, uint8_t* buff)
{
	int i, j, k;
    for(i=0; i<frame->height; i++)
    {
        memcpy(buff + frame->width*i, frame->data[0]+frame->linesize[0]*i, frame->width);
    }
    for(j=0; j<frame->height/2; j++)
    {
        memcpy(buff + frame->width*i + frame->width/2*j, frame->data[1] + frame->linesize[1]*j, frame->width/2);
    }
    for(k=0; k<frame->height/2; k++)
    {
        memcpy(buff + frame->width*i +frame->width/2*j + frame->width/2*k, frame->data[2]+frame->linesize[2]*k, frame->width/2);
    }
	return buff;
}

/*****************************************************
 *	功能:关闭解码器,释放内存
 *  参数:
 *
 *  返回值:无
 * **************************************************/

void free_decoder()
{
	av_parser_close(parser);
    avcodec_free_context(&c);
    av_frame_free(&frame);
    av_packet_free(&pkt);
    if(imgbuff !=NULL)
    {
    	if(imgbuff->data != NULL)
    	{
    		free(imgbuff->data);
    		imgbuff->data = NULL;
    	}
    	free(imgbuff);
    	imgbuff = NULL;
    }

    printf("In C language free all requested memory! \n");

}

test.c

#include <stdio.h>
#include "ffmpeg.h"
int main(int argc, const char **argv)
{
	return 0;
}

四.执行Makefile.sh脚本，生成ffmpeg.js ffmpeg.wasm解码库

Makefile.sh

echo "start building"
export TOTAL_MEMORY=67108864
export EXPORTED_FUNCTIONS="[ \
	'_init_decoder', \
	'_decoder_raw', \
	'_free_decoder', \
	'_main'

]"

emcc test.c ffmpeg.c ../lib/libavcodec.a ../lib/libavutil.a ../lib/libswscale.a \
	-O2 \
	-I "../inc" \
	-s WASM=1 \
	-s USE_PTHREADS=1 \
	-s TOTAL_MEMORY=${TOTAL_MEMORY} \
	-s EXPORTED_FUNCTIONS="${EXPORTED_FUNCTIONS}" \
	-s EXTRA_EXPORTED_RUNTIME_METHODS="['addFunction']" \
	-s RESERVED_FUNCTION_POINTERS=14 \
	-s FORCE_FILESYSTEM=1 \
	-o ../js/libffmpeg.js

echo "finish building"

五.实现websocket协议服务器，推送码流

参考文章：WebSocket的C++服务器端实现
WebSocket协议解析

/*******************************************************************************
 * 名称: server_thread_fun
 * 功能: 线程管理websocket服务器
 * 形参: arg： WebSocket_server 结构体
 *          
 *          
 * 返回: 无
 * 说明: 无
 ******************************************************************************/

void server_thread_fun(void *arg)
{
    int ret, j;
    int cfd;
    char ip[16] = "";
    struct sockaddr_in serverAddr;
    struct sockaddr_in clientAddr;
    socklen_t client_len = sizeof(clientAddr);
    WebSocket_server *wss = (WebSocket_server *)arg;
    memset(&serverAddr, 0, sizeof(serverAddr)); 
    serverAddr.sin_family = AF_INET;            
    serverAddr.sin_port = htons(wss->port);
    serverAddr.sin_addr.s_addr = INADDR_ANY;

    wss->fd = socket(AF_INET, SOCK_STREAM, 0);
    if(wss->fd < 0)
    {
        printf("server can't create socket\n");
        exit(1);
    }
    
    //设置端口复用，绑定监听
    int opt = 1;
    setsockopt(wss->fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
    bind(wss->fd, (struct sockaddr*)&serverAddr, sizeof(serverAddr));
    listen(wss->fd, 128);

    //创建一个句柄
    int epfd = epoll_create(1);
    if(epfd < 0)
    {
        perror("");
        exit(1);
    }

    struct epoll_event ev, evs[1024];
    ev.data.fd = wss->fd;
    ev.events = EPOLLIN | EPOLLET;
    epoll_ctl(epfd, EPOLL_CTL_ADD, wss->fd, &ev);

    while(1)
    {
        int n = epoll_wait(epfd, evs, 1024, -1);    //epoll监听
        if( n < 0)
        {
            printf("server start epoll_wait failed\n");
            exit(1);
        }

        for(j=0; j<n; j++)
        {
            if((evs[j].events & EPOLLERR) || (evs[j].events & EPOLLHUP))    //epoll连接错误
            {
                //printf("epoll error accept close:%d \n",evs[j].data.fd);
                ev.data.fd = evs[j].data.fd;
                if(epoll_ctl(epfd, EPOLL_CTL_DEL, evs[j].data.fd,&ev) < 0)
                {
                    printf("server epoll_ctl:EPOLL_CTL_DEL failed\n");
                    close(epfd);
                    exit(1);
                }
                arrayRemoveItem(wss->client_fd_array, EPOLL_RESPOND_NUM, evs[j].data.fd);//client close 从数组中移除fd
                close(evs[j].data.fd);
            }
            else if(evs[j].data.fd == wss->fd)  //接入客户端
            {
                cfd = accept(wss->fd, (struct sockaddr *)&clientAddr, &client_len);     //提取新的连接
                if(cfd >=0 )
                {
                    ev.data.fd = cfd;
                    epoll_ctl(epfd, EPOLL_CTL_ADD, cfd, &ev); 
                }
                //printf("websocketV2 client ip=%s port=%d fd=%d\n",inet_ntop(AF_INET, &clientAddr.sin_addr.s_addr, ip, 16),ntohs(clientAddr.sin_port),cfd);
            }
            else if(evs[j].events & EPOLLIN)//接收数据事件
            {
                memset(wss->buf, 0, sizeof(wss->buf));
                ret = wss->callback(wss, evs[j].data.fd, wss->buf, sizeof(wss->buf));//回调函数
                if(ret <= 0)    //ret<0时，检查异常，决定是否主动解除连接
                {
                    if( errno >0 && (errno == EAGAIN || errno == EINTR))
                        ;
                    else
                    {   
                        //printf("accept close=%d errno =%d\n",evs[j].data.fd,errno);
                        ev.data.fd = evs[j].data.fd;
                        
                        if(epoll_ctl(epfd, EPOLL_CTL_DEL, evs[j].data.fd, &ev) < 0)
                        {
                            printf("server epoll_ctl:EPOLL_CTL_DEL failed\n");
                            close(epfd);
                            exit(1);
                        }
                        arrayRemoveItem(wss->client_fd_array, EPOLL_RESPOND_NUM, evs[j].data.fd);//client close 从数组中移除fd
                        close(evs[j].data.fd);
                    }
                }
            }
            else if(evs[j].events & EPOLLOUT)   //发送数据事件
                ;
        }   
    }
    close(epfd);    //关闭句柄
    close(wss->fd);
    
}

/*******************************************************************************
 * 名称: server_thread_fun
 * 功能: 回调函数
 * 形参: wss：WebSocket_server结构体
 *          fd:句柄
 *          buf：发送数据buf
 *          buflen： 数据大小   
 *          
 * 返回: 无
 * 说明: 无
 ******************************************************************************/
int ret1=0;
int server_callback(WebSocket_server *wss, int fd, char *buf, unsigned int buflen)
{
    ret1 = webSocket_recv(fd, buf, buflen, NULL);   //接收客户端发过来的数据
    if(ret1 > 0)
    {
        #if 0
            printf(" client->server recv msg fd=%d mgs=%s\n", fd, buf);
            if(strstr(buf, "hi~") != NULL)
                ret1 = webSocket_send(fd, "I am server", strlen("I am server"), false, WDT_TXTDATA);
        #endif
    }
    else if( ret1 < 0)
    {
        if(strncmp(buf, "GET", 3) == 0)
        {
            ret1 = webSocket_serverLinkToClient(fd, buf, ret1); //服务器连接客户端
            if(ret1 > 0)
            {
                arrayAddItem(wss->client_fd_array,EPOLL_RESPOND_NUM, fd );//连接成功后将fd添加到数组中
            }
        }
    }
    return ret1;    
}
/*******************************************************************************
 * 名称: arrayAddItem
 * 功能: 添加cfd到数组
 * 形参: array:二维数组
 *          arraySize: 句柄数量
 *          value: cfd
 * 返回: 
 * 说明: 无
 ******************************************************************************/
int arrayAddItem(int array[][2], int arraySize, int value)
{
    int i;
    for(i=0; i<arraySize; i++)
    {
        if(array[i][1] ==0 )
        {
            array[i][0] = value;
            array[i][1] = 1;
            return 0;
        }
    }

    return -1;
}

/*******************************************************************************
 * 名称: arrayRemoveItem
 * 功能: 从数组中删除cfd
 * 形参: array:二维数组
 *          arraySize: 句柄数量
 *          value: cfd
 * 返回: 
 * 说明: 无
 ******************************************************************************/

int arrayRemoveItem(int array[][2], int arraySize, int value)
{
    int i = 0;
    for(i=0; i<arraySize; i++)
    {
        if(array[i][0] == value)
        {
            array[i][0] = 0;
            array[i][1] = 0;
            return 0;
        }
    }
    return -1;
}

六.web端实现

webgl.js

function Texture(gl) {
    this.gl = gl;
    this.texture = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, this.texture);

    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);

    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
}

Texture.prototype.bind = function (n, program, name) {
    var gl = this.gl;
    gl.activeTexture([gl.TEXTURE0, gl.TEXTURE1, gl.TEXTURE2][n]);
    gl.bindTexture(gl.TEXTURE_2D, this.texture);
    gl.uniform1i(gl.getUniformLocation(program, name), n);
};

Texture.prototype.fill = function (width, height, data) {
    var gl = this.gl;
    gl.bindTexture(gl.TEXTURE_2D, this.texture);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.LUMINANCE, width, height, 0, gl.LUMINANCE, gl.UNSIGNED_BYTE, data);
};

function WebGLPlayer(canvas, options) {
    this.canvas = canvas;
    this.gl = canvas.getContext("webgl") || canvas.getContext("experimental-webgl");
    this.initGL(options);
}

WebGLPlayer.prototype.initGL = function (options) {
    if (!this.gl) {
        console.log("[ER] WebGL not supported.");
        return;
    }

    var gl = this.gl;
    gl.pixelStorei(gl.UNPACK_ALIGNMENT, 1);
    var program = gl.createProgram();
    var vertexShaderSource = [
        "attribute highp vec4 aVertexPosition;",
        "attribute vec2 aTextureCoord;",
        "varying highp vec2 vTextureCoord;",
        "void main(void) {",
        " gl_Position = aVertexPosition;",
        " vTextureCoord = aTextureCoord;",
        "}"
    ].join("\n");
    var vertexShader = gl.createShader(gl.VERTEX_SHADER);
    gl.shaderSource(vertexShader, vertexShaderSource);
    gl.compileShader(vertexShader);
    var fragmentShaderSource = [
        "precision highp float;",
        "varying lowp vec2 vTextureCoord;",
        "uniform sampler2D YTexture;",
        "uniform sampler2D UTexture;",
        "uniform sampler2D VTexture;",
        "const mat4 YUV2RGB = mat4",
        "(",
        " 1.1643828125, 0, 1.59602734375, -.87078515625,",
        " 1.1643828125, -.39176171875, -.81296875, .52959375,",
        " 1.1643828125, 2.017234375, 0, -1.081390625,",
        " 0, 0, 0, 1",
        ");",
        "void main(void) {",
        " gl_FragColor = vec4( texture2D(YTexture, vTextureCoord).x, texture2D(UTexture, vTextureCoord).x, texture2D(VTexture, vTextureCoord).x, 1) * YUV2RGB;",
        "}"
    ].join("\n");

    var fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
    gl.shaderSource(fragmentShader, fragmentShaderSource);
    gl.compileShader(fragmentShader);
    gl.attachShader(program, vertexShader);
    gl.attachShader(program, fragmentShader);
    gl.linkProgram(program);
    gl.useProgram(program);
    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
        console.log("[ER] Shader link failed.");
    }
    var vertexPositionAttribute = gl.getAttribLocation(program, "aVertexPosition");
    gl.enableVertexAttribArray(vertexPositionAttribute);
    var textureCoordAttribute = gl.getAttribLocation(program, "aTextureCoord");
    gl.enableVertexAttribArray(textureCoordAttribute);

    var verticesBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, verticesBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([1.0, 1.0, 0.0, -1.0, 1.0, 0.0, 1.0, -1.0, 0.0, -1.0, -1.0, 0.0]), gl.STATIC_DRAW);
    gl.vertexAttribPointer(vertexPositionAttribute, 3, gl.FLOAT, false, 0, 0);
    var texCoordBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, texCoordBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([1.0, 0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 1.0]), gl.STATIC_DRAW);
    gl.vertexAttribPointer(textureCoordAttribute, 2, gl.FLOAT, false, 0, 0);

    gl.y = new Texture(gl);
    gl.u = new Texture(gl);
    gl.v = new Texture(gl);
    gl.y.bind(0, program, "YTexture");
    gl.u.bind(1, program, "UTexture");
    gl.v.bind(2, program, "VTexture");
}

WebGLPlayer.prototype.renderFrame = function (videoFrame, width, height, uOffset, vOffset) {
    if (!this.gl) {
        console.log("[ER] Render frame failed due to WebGL not supported.");
        return;
    }

    var gl = this.gl;
    gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
    gl.clearColor(0.0, 0.0, 0.0, 0.0);
    gl.clear(gl.COLOR_BUFFER_BIT);

    gl.y.fill(width, height, videoFrame.subarray(0, uOffset));
    gl.u.fill(width >> 1, height >> 1, videoFrame.subarray(uOffset, uOffset + vOffset));
    gl.v.fill(width >> 1, height >> 1, videoFrame.subarray(uOffset + vOffset, videoFrame.length));

    gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
};

WebGLPlayer.prototype.fullscreen = function () {
	  var canvas = this.canvas;
    if (canvas.RequestFullScreen) {
        canvas.RequestFullScreen();
    } else if (canvas.webkitRequestFullScreen) {
        canvas.webkitRequestFullScreen();
    } else if (canvas.mozRequestFullScreen) {
        canvas.mozRequestFullScreen();
    } else if (canvas.msRequestFullscreen) {
        canvas.msRequestFullscreen();
    } else {
        alert("This browser doesn't supporter fullscreen");
    }
};

WebGLPlayer.prototype.exitfullscreen = function (){
    if (document.exitFullscreen) {
        document.exitFullscreen();
    } else if (document.webkitExitFullscreen) {
        document.webkitExitFullscreen();
    } else if (document.mozCancelFullScreen) {
        document.mozCancelFullScreen();
    } else if (document.msExitFullscreen) {
        document.msExitFullscreen();
    } else {
        alert("Exit fullscreen doesn't work");
    }
}

video.js //websocket接收端

var canvas;
var webglPlayer;
var width = 0;
var height = 0;
var socketurl = "ws://192.168.1.213:8000"; //websocket服务器ip,port

//codeid=1,选择解码H.265裸流
function playH265()
{
	play(1);
}

//codeid=0,选择解码H.264裸流
function playH264()
{
	play(0);
}

function play(codeid) 
{
	//创建websocket对象 	
	var websocket = new WebSocket(socketurl);
	websocket.binaryType = "arraybuffer";	//设置客户端接收数据格式
	
	//浏览器-->websocket服务器 发送数据建立连接
	websocket.onopen = function()	
	{
		//判断连接服务器状态
		if(websocket.readyState == 0){
			alert("browser connect websocket server failed,please reconnect");
			return;
		}
		else if(websocket.readyState == 1){
			console.log("In javascript language connect websocket server success!");	
		}
		websocket.send("connect websocket server");//向服务器发送数据
		//初始化解码器 1=h265  0=h264
		var ret = Module._init_decoder(codeid);
		if(ret != 0)
		{
			console.log("init decoder failed!");
			return ;
		}
			
	};

	//接收websocket服务器数据
	let ptr;
	websocket.onmessage = function(evt)
	{
		let buff = null;
		let size = 0;
		size = evt.data.byteLength;		
		buff = new Uint8Array(evt.data);	//evt.data里包含裸流数据以ArrayBuffer对象形式存放
		
		let buf = Module._malloc(size);		//手机端不支持这样使用函数，webAssembly浏览器原因不兼容
		
		Module.HEAPU8.set(buff, buf);		//buf是裸流数据
	
		ptr = Module._decoder_raw(buf, size);	//ffmpeg解码

		width = Module.HEAPU32[ptr/4];		//Webgl渲染yuv420p数据
		height = Module.HEAPU32[ptr/4 +1];
		let imgbuffptr = Module.HEAPU32[ptr/4 +2];
		let imgbuff = Module.HEAPU8.subarray(imgbuffptr, imgbuffptr + width*height*3/2);																	
		
		showYuv420pdata(width, height, imgbuff);

		if(buf!=null)	//释放内存
		{
			Module._free(buf);
			buf=null;
		}
	};

	//websocket关闭连接
	websocket.onclose = function()
	{
		//关闭解码器，释放内存
		Module._free_decoder();
		console.log("In javascript language websocket client close !");
	};
	
	//websocket通信发生错误连接
	websocket.onerror = function()
	{
		alert("websocket 服务器未启动！");
		return ;
	}
}

/***************************************************************
	webgl渲染yuv420p数据
**************************************************************/
function showYuv420pdata(width, height, data)
{
	let ylenght = width*height;
	let uvlenght = width*height/4;
	if(!webglPlayer)
	{
		const canvasId = "canvas";
		canvas = document.getElementById(canvasId);
		webglPlayer = new WebGLPlayer(canvas, {
			preserveDrawingBuffer:false
		});
	}
	webglPlayer.renderFrame(data, width, height, ylenght,uvlenght);
}

/***************************************************************
	webgl方法实现全屏功能

**************************************************************/
function fullscreen()
{
	if(!webglPlayer)	
	{
		alert("没有渲染webgl暂时不能全屏");
		return;
	}
	webglPlayer.fullscreen();	
}

七.结果

由于2020年6月份做的，当时忘记截图记录了，没有图片。说下这种方案实现效果，测试结果。
解码1080p 30fps的H265码流, 延迟300~450ms,
解码4k 30fps的H265码流，播放越久延迟越重，不行。适合1080p分辨率以下的。文章来源地址https://www.toymoban.com/news/detail-793772.html

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