以编程方式修剪 mp3 文件

Question

嘿我需要在我的应用程序中修剪/剪切/编辑音频文件，我尝试使用 ffmpeg 但我不知道如何安装此库或什至如何使用它.. 所以，有人可以给我是一个很好的指南，如何将 ffmpeg 2.3 与 android ndk r10 一起用于 windows 7 64bit？或任何其他建议如何剪切 mp3 文件？

当我将 ffmpeg 库添加到我的项目时，我在控制台中收到此错误：

    [2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] C:\Users\David\Workspace\RecordTheLast20Minutes\res\values\styles.xml:7: error: Error retrieving parent for item: No resource found that matches the given name 'Theme.AppCompat.Light'.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] C:\Users\David\Workspace\RecordTheLast20Minutes\res\values-v14\styles.xml:8: error: Error retrieving parent for item: No resource found that matches the given name 'Theme.AppCompat.Light.DarkActionBar'.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] C:\Users\David\Workspace\RecordTheLast20Minutes\res\values\styles.xml:7: error: Error retrieving parent for item: No resource found that matches the given name 'Theme.AppCompat.Light'.
[2014-07-29 00:04:06 - RecordTheLast20Minutes] C:\Users\David\Workspace\RecordTheLast20Minutes\res\values-v14\styles.xml:8: error: Error retrieving parent for item: No resource found that matches the given name 'Theme.AppCompat.Light.DarkActionBar'.
[2014-07-29 00:07:28 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:28 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:28 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:28 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:28 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:28 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:29 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:29 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:29 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:29 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:29 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:29 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:32 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:32 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:32 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:32 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:32 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:32 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:50 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:50 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:50 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:50 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:50 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:50 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:52 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:52 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:52 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:52 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:07:52 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:07:52 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:10:18 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:10:18 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:10:18 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:10:18 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:10:18 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:10:18 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:10:19 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:10:19 - RecordTheLast20Minutes] res\drawable-hdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:10:19 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:10:19 - RecordTheLast20Minutes] res\drawable-mdpi\ic_launcher.jpg:0: Originally defined here.
[2014-07-29 00:10:19 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.png:0: error: Resource entry ic_launcher is already defined.
[2014-07-29 00:10:19 - RecordTheLast20Minutes] res\drawable-xhdpi\ic_launcher.jpg:0: Originally defined here.

所有像 R.raw.music 或 R.menu.actionbarmenu R.layout.activity 这样的东西现在都是错误，：R cannot be resolved to a variable 和 ffmpeg -t 30 -i inputfile.mp3 -acodec copy outputfile.mp3 行也是一个错误：

Multiple markers at this line
    - Syntax error on token "copy", @ expected
    - Syntax error on token "inputfile", delete this 
     token
    - Syntax error on token(s), misplaced 
     construct(s)
    - Syntax error on token(s), misplaced 
     construct(s)
    - Syntax error on token "30", delete this token

Ty 帮忙 :)

Answer 1

有许多开源 Android ffmpeg 项目，其中一个似乎使用最多或讨论最多的是：

https://github.com/guardianproject/android-ffmpeg

这在 Android 平台上提供了 ffmpeg，并且相关项目提供了一个 Java 包装器（使用 Runtime.getRuntime().exec 方法，而不是我最初认为的 JNI）以允许您在常规 Java Android 应用程序中使用它：

https://github.com/guardianproject/android-ffmpeg-java

上面的顶级项目包括构建说明和一些测试安装的示例。

下面显示了一些使用 ffmpeg 二进制文件的 Java Wrapper 项目方法声明示例。您可以在您下载的android-ffmpeg-java项目中的文件'android-ffmpeg-java/src/org/ffmpeg/android/FfmpegController.java'中看到完整的代码：

public void extractAudio (Clip mdesc, String audioFormat, File audioOutPath, ShellCallback sc) throws IOException, InterruptedException 
    { ...

public void concatAndTrimFilesMPEG (ArrayList<Clip> videos,Clip out, boolean preConvert, ShellCallback sc) throws Exception
{ ...

public Clip convertToMPEG (Clip mediaIn, String outPath, ShellCallback sc) throws Exception
{ ...

如果您查看这些内容，您应该能够了解如何添加一个完全符合您要求的内容。本质上，这些方法使用 Runtime.getRuntime().exec 函数调用带有特定任务所需参数的 cmd 行 ffmpeg。

根据过去在 Android 上使用 Runtime.getRuntime().exec 的经验，有几点需要注意：

• 早期版本的 Android 有一个错误，这意味着 Runtime.getRuntime().exec 有时会挂起：https://stackoverflow.com/a/11411709/334402
• Runtime.getRuntime().exec 需要谨慎使用 - 请查看此链接了解更多信息：http://www.javaworld.com/article/2071275/core-java/when-runtime-exec---won-t.html
• 据我所知，您需要在有根设备上才能在 Android 上使用 Runtime.getRuntime().exec。自从我上次查看以来，这可能已经发生了变化，但值得检查这对您的应用程序是否重要。