学步园

我用java调用mencoder实施转码，但是转码过程中出现子进程阻塞，而且还是看了API才知道这个问题的。因为mencoder的控制台输出信息很多，把缓存区所有的空间占满了，所以程序不能执行后面的程序，mencoder就只能转码28秒的视频，所以需要建立线程及时清空缓存区。

新建一个类StreamGobble类：

package thss.jmencoder;<br /> import java.io.BufferedReader;<br /> import java.io.IOException;<br /> import java.io.InputStream;<br /> import java.io.InputStreamReader;<br /> public class StreamGobble extends Thread {<br /> InputStream is;<br /> String type; </p> <p> StreamGobble(InputStream is, String type) {<br /> this.is = is;<br /> this.type = type;<br /> } </p> <p> public void run() {<br /> try {<br /> InputStreamReader isr = new InputStreamReader(is);<br /> BufferedReader br = new BufferedReader(isr);<br /> String line = null;<br /> while ((line = br.readLine()) != null)<br /> System.out.println(type + ">" + line);<br /> } catch (IOException ioe) {<br /> ioe.printStackTrace();<br /> }<br /> }<br /> } </p> <p>

在main函数中调用Runtime/Process执行转码

String line = value.toString();<br /> String[] str = line.split(" ");<br /> String fOutput = null;<br /> fOutput = str[3] + ".flv";<br /> Process process = null;<br /> try {<br /> Runtime runtime = Runtime.getRuntime();<br /> process = runtime .exec("mencoder -ofps 30000/1001 -vf harddup"<br /> + " /user/student/data/"+str[0]<br /> + " -ss "+str[1]+" -endpos "+str[2]+" -sws 2 -of lavf -ovc lavc -lavcopts "<br /> + "vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 "<br /> + "-nosound -srate 22050 -o /user/student/data/"+fOutput);<br /> new StreamGobble(process.getInputStream(), "INFO").start();<br /> new StreamGobble(process.getErrorStream(), "ERROR").start();<br /> int status = process.waitFor();<br /> System.out.println("Process exitValue: " + status);<br /> } catch (Throwable t) {<br /> t.getStackTrace();<br /> } finally {<br /> if (process == null)<br /> process.destroy();<br /> process = null;<br /> }<br />