如何计算 一个音视频文件 (.ts)文件 (包含pcr信息). 播放所使用的带宽

以下是计算一个音视频文件,播放所需要带宽的程序:


public int getBitrate(String path) {





File f = new File(path);


if (f.exists()) {


int mpegPackets = 0;


int getpcr = 0;


long pcr0 = 0;


long pcr1;


int pid = 0;


try {


FileInputStream in = new FileInputStream(f);


while (true) {


byte[] b = new byte[188];




int ret = in.read(b, 0, 188);


if (ret == -1)


break;


mpegPackets++;


if (b[0] != 0x47) {


return -1;


}


System.out.println("");


System.out.println(mpegPackets + " : ");


for(int k=0; k<ret; k++){


System.out.print(Integer.toHexString(b[k]&0xFF) + " ");


if(k%10 ==0){


System.out.println("");


}


}


if ((((b[3] >> 4) & 0x3) & 0x02) != 0) {//ptati判断adaptation_field_control =='10' || ='11')


//确定后面为adaptation_field


if (b[4] == 0) //adaptation_field_length = 0 则退出循环


continue;


if ((b[5] & 0x10) != 0) { //对应 PCG_flag = 0 则表示此packet 不包含pcr 信息


if (getpcr == 10) { //当找到第11个包含pcr 信息的packet


pid = ((b[1] & 0xff & 0x1f) << 8)


| (b[2] & 0xff);


int tmp;


pcr0 = ((((b[6] & 0xff) << 24)


+ ((b[7] & 0xff) << 16)


+ ((b[8] & 0xff) << 8) + (b[9] & 0xff)));


pcr0 <<= 1;


if ((b[10] & 0xff & 0x80) != 0)


pcr0 |= 1;


//pcr0 为 program_clock_reference_base (33bit)


pcr0 *= 300;


//OPCR(i) = OPCR_base(i)*300 + OPCR_ext(i)


tmp = ((b[10] & 0xff & 1) << 8) + b[11];


//tmp 为 program_clock_reference_extension (9bit)


pcr0 += tmp;


mpegPackets = 0;


}


if ((getpcr > 20)


&& pid == (((b[1] & 0xff & 0x1f) << 8) | (b[2] & 0xff))) {


//从第21个包含pcr信息的packet的包并且pid与"第11个包含pcr 信息的packet的pid"相同


int tmp;


pcr1 = ((((b[6] & 0xff) << 24)


+ ((b[7] & 0xff) << 16)


+ ((b[8] & 0xff) << 8) + (b[9] & 0xff)));


pcr1 <<= 1;


if ((b[10] & 0xff & 0x80) != 0)


pcr1 |= 1;


pcr1 *= 300;


tmp = ((b[10] & 0xff & 1) << 8) + b[11] & 0xff;


pcr1 += tmp;


long PCRdelta = pcr1 - pcr0;


double bitRate = ((40608 * mpegPackets * 1.0) / PCRdelta) * 1000000;


//40608 = 188 * 216


return (int) bitRate;


}


getpcr++;


}


}


}


} catch (FileNotFoundException e) {


e.printStackTrace();


} catch (IOException e) {


e.printStackTrace();


}




} else


return 0;


return 0;


}

以上是根据pcr来计算播放所需要带宽

filippo.le@gmail.com

转自http://blog.csdn.net/charlie0895/article/details/1755690