Question

我正在为java中的ffmpeg创建进度条。因此，我需要执行一个命令，然后阅读所有进度：

String[] command = {"gnome-terminal", "-x", "/bin/sh", "-c","ffmpeg -i /home/tmp/F.webm /home/tmp/converted1.mp4"};

Process process = Runtime.getRuntime().exec(command);

这完美运行。但是，我需要捕获所有进度来制作进度条。那么如何从java中读取数据？

Answer 1

以下是一个完整的示例，可以帮助您入门

import java.io.*;
import java.util.Scanner;
import java.util.regex.Pattern;

class Test {
  public static void main(String[] args) throws IOException {
    ProcessBuilder pb = new ProcessBuilder("ffmpeg","-i","in.webm","out.mp4");
    final Process p = pb.start();

    new Thread() {
      public void run() {

        Scanner sc = new Scanner(p.getErrorStream());

        // Find duration
        Pattern durPattern = Pattern.compile("(?<=Duration: )[^,]*");
        String dur = sc.findWithinHorizon(durPattern, 0);
        if (dur == null)
          throw new RuntimeException("Could not parse duration.");
        String[] hms = dur.split(":");
        double totalSecs = Integer.parseInt(hms[0]) * 3600
                         + Integer.parseInt(hms[1]) *   60
                         + Double.parseDouble(hms[2]);
        System.out.println("Total duration: " + totalSecs + " seconds.");

        // Find time as long as possible.
        Pattern timePattern = Pattern.compile("(?<=time=)[\\d.]*");
        String match;
        while (null != (match = sc.findWithinHorizon(timePattern, 0))) {
          double progress = Double.parseDouble(match) / totalSecs;
          System.out.printf("Progress: %.2f%%%n", progress * 100);
        }
      }
    }.start();

  }
}

<强>输出：

Total duration: 117.7 seconds.
Progress: 7.71%
Progress: 16.40%
Progress: 25.00%
Progress: 33.16%
Progress: 42.67%
Progress: 51.35%
Progress: 60.57%
Progress: 69.07%
Progress: 78.02%
Progress: 86.49%
Progress: 95.94%
Progress: 99.97%

您也可以考虑为ffmpeg使用某种Java绑定，例如jjmpeg，它可以以更强大的方式提供您所需的内容。

修改的

使用ffmpeg 2.0，时间输出为HH:mm:ss.S，因此timePattern需要包含:

Pattern timePattern = Pattern.compile("(?<=time=)[\\d:.]*");

此外，dur需要在:上拆分并汇总在一起

String[] matchSplit;
while (null != (match = sc.findWithinHorizon(timePattern, 0))) {
    matchSplit = match.split(":")
    double progress = Integer.parseInt(matchSplit[0]) * 3600 +
        Integer.parseInt(matchSplit[1]) * 60 +
        Double.parseDouble(matchSplit[2]) / totalSecs;
//...

Answer 2

您可以尝试解析ffmpeg输出，并以某种方式了解已完成的工作。但这很难并且不稳定。我们（ffmpeg用户）和ffmpeg本身都不知道也无法知道处理需要多长时间。

根据我的经验，最简单的方法是实现一种启发式方法。假设线性处理的时间取决于文件大小。这种方法“错误”但足够好且非常简单。现在运行您的处理与您在现实生活中使用的几个不同大小的文件完全相同的选项。创建大小到时间的映射。进行统计分析并创建像time = something + coef * size这样的公式。

现在您可以创建流程栏了。与大多数工艺条一样，它应该达到~95％，然后等待实际终止该过程。

它非常简单，并且比任何其他更复杂的解决方案都更糟糕。

Answer 3

*我已使用以下代码成功显示ffmpeg命令的ProgressBar。

  try {
                Scanner sc = new Scanner(process.getErrorStream());

                // Find duration
                Pattern durPattern = Pattern.compile("(?<=Duration: )[^,]*");
                String dur = sc.findWithinHorizon(durPattern, 0);
                Log.e("duration"+dur);
                String givenDateString = dur;
                SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss.S");
                sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
                try {
                    Date mDate = sdf.parse(givenDateString);
                    totalDuration = mDate.getTime();
                    System.out.println("Duration in milli :: " + totalDuration);
                } catch (ParseException e) {
                    e.printStackTrace();
                }

                // Find time as long as possible.
                Pattern timePattern = Pattern.compile("(?<=time=)[\\d:.]*");
                String match;
                String[] matchSplit;
                while (null != (match = sc.findWithinHorizon(timePattern, 0))) {
                    if (isCancelled()) {
                        return;
                    }
                    Log.e("match"+match);
                    String givenDateString1 = match;
                    SimpleDateFormat sdf1 = new SimpleDateFormat("HH:mm:ss.S");
                    sdf1.setTimeZone(TimeZone.getTimeZone("GMT"));
                    try {
                        Date mDate = sdf1.parse(givenDateString1);
                        currentDuration = mDate.getTime();
                        System.out.println("Time in milli :: " + currentDuration);
                    } catch (ParseException e) {
                        e.printStackTrace();
                    }
                    Double percentage = (double) 0;

                    long currentSeconds = (int) (currentDuration);
                    long totalSeconds = (int) (totalDuration);

                    // calculating percentage
                     percentage =(((double)currentSeconds)/totalSeconds)*100;


                    Log.e("Progress"+percentage);
                    publishProgress(""+percentage);
                }
            }catch (Exception e){
                e.printStackTrace();
            }

如何从java读取ffmpeg响应并使用它来创建进度条？

3 个答案: