Motion JPEG in Flash and Java-白红宇

Motion JPEG in Flash and Java

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发布时间：2019-06-28

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http://www.walking-productions.com/notslop/2010/04/20/motion-jpeg-in-flash-and-java/

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I recently had the opportunity to develop a solution in both Java and Flash for pulling Motion JPEG streams from IP cameras and thought it might be nice to document a bit.

Motion JPEG is generally served via HTTP from IP cameras as a single file. Meaning, the connection stays open and the camera just keeps sending individual JPEG images down the pipe. The images should start with a MIME boundary message such as:

--myboundary
 Content-Type: image/jpeg
 Content-Length: 22517


 --randomstring
 Content-Type: image/jpeg
 Content-Length: 22598

The key in the development is to find the boundary and save the bytes between each and treat that as a JPEG image. Neither of these snippets are great or even complete but they should give you a bit of a start.

Java:

package com.mobvcasting.mjpegparser;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.net.Authenticator;

import java.net.PasswordAuthentication;

import java.net.URL;

public

class MJPEGParser {

/**

@param

args

public

static

void main(String[] args) {

MJPEGParser mp =

new MJPEGParser("http://192.168.1.10/mjpg/video.mjpg", "username", "password");

}

public MJPEGParser(String mjpeg_url)

{

this(mjpeg_url,

null,

null);

}

public MJPEGParser(String mjpeg_url, String username, String password)

{

int imageCount = 0;

try {

if (username !=

null && password !=

null)

{

Authenticator.setDefault(

new HTTPAuthenticator(username, password));

}

URL url =

new URL(mjpeg_url);

BufferedReader in =

new BufferedReader(

new InputStreamReader(url.openStream()));

String inputLine;

int lineCount = 0;

boolean lineCountStart =

false;

boolean saveImage =

false;

while ((inputLine = in.readLine()) !=

null) {

Should be checking just for "--" probably

if (inputLine.lastIndexOf("--myboundary") > -1)

{

Got an image boundary, stop last image

Start counting lines to get past:

Content-Type: image/jpeg

Content-Length: 22517

saveImage =

false;

lineCountStart =

true;

System.out.println("Got a new boundary");

System.out.println(inputLine);

}

else

if (lineCountStart)

{

lineCount++;

if (lineCount >= 2)

{

lineCount = 0;

lineCountStart =

false;

imageCount++;

saveImage =

true;

System.out.println("Starting a new image");

}

else

if (saveImage)

{

System.out.println("Saving an image line");

}

else {

System.out.println("What's this:");

System.out.println(inputLine);

}

in.close();

}

catch (IOException e) {

e.printStackTrace();

}

static

class HTTPAuthenticator

extends Authenticator {

private String username, password;

public HTTPAuthenticator(String user, String pass) {

username = user;

password = pass;

}

protected PasswordAuthentication getPasswordAuthentication() {

System.out.println("Requesting Host : " + getRequestingHost());

System.out.println("Requesting Port : " + getRequestingPort());

System.out.println("Requesting Prompt : " + getRequestingPrompt());

System.out.println("Requesting Protocol: "

+ getRequestingProtocol());

System.out.println("Requesting Scheme : " + getRequestingScheme());

System.out.println("Requesting Site : " + getRequestingSite());

return

new PasswordAuthentication(username, password.toCharArray());

}

ActionScript 3

import flash.display.Sprite;

import flash.errors.*;

import flash.events.*;

import flash.net.URLRequest;

import flash.net.URLStream;

import flash.utils.ByteArray;

var stream:URLStream;

var mjpegBuffer:ByteArray =

new ByteArray();

The actual image

var imageBytes:ByteArray;

= new ByteArray();

The chars at the end of the image

var endPos:String = "\n--myboundary";

Started to find, finished finding

var done:Boolean =

false;

var started:Boolean =

false;

Don't know why I have to save these to a ByteArray to do the comparisons but it seems I do

var startBytes:ByteArray =

new ByteArray();

var startByte:

int = 0xFF;

var secondByte:

int = 0xD8;

startBytes.writeByte(0xFF);

startBytes.writeByte(0xD8);

trace(startBytes.length);

var startNum:

int = startBytes[0];

trace(startNum);

var nextNum:

int = startBytes[1];

trace(nextNum);

Open the stream

stream =

new URLStream();

var request:URLRequest =

new URLRequest("http://192.168.1.10/mjpg/video.mjpg?resolution=160x90&fps=1");

configureListeners(stream);

try {

stream.load(request);

}

catch (error:Error) {

trace("Unable to load requested URL.");

}

function configureListeners(dispatcher:EventDispatcher):

void {

dispatcher.addEventListener(ProgressEvent.PROGRESS, progressHandler);

}

function progressHandler(event:Event):

void

{

trace("Running");

stream.readBytes(mjpegBuffer,mjpegBuffer.length,stream.bytesAvailable);

for (var i:

int = 0; i < mjpegBuffer.length; i++)

{

var currentByte:

int = mjpegBuffer[i];

var nextByte:

int = mjpegBuffer[i+1];

var thirdByte:

int = mjpegBuffer[i+2];

var fourthByte:

int = mjpegBuffer[i+3];

var randNum:Number = Math.random();

if (randNum > .5 && randNum < .6) { trace(currentByte); }

if (!started)

{

if (currentByte == startNum && nextByte == nextNum)

{

trace("Started");

started =

true;

imageBytes =

new ByteArray();

imageBytes.writeByte(currentByte);

imageBytes.writeByte(0xD8);

Gets written in the else

}

else

{

if (currentByte == endPos.charCodeAt(0) && nextByte == endPos.charCodeAt(1) && thirdByte == endPos.charCodeAt(2) && fourthByte == endPos.charCodeAt(3))

{

trace("done");

trace(imageBytes);

done =

true;

started =

false;

var loader:Loader =

new Loader();

loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onByteArrayLoaded)

loader.loadBytes(imageBytes);

stream.close();