Kotlin编写AudioExtractor视频解析七

　　上篇文章讲解了怎么利用FFmpeg来合并一个音视频，今天我们继续来讲解一下利用FFmpeg来处理视频的时间，比如裁剪一段视频，然后合并输出新的视频地址，看了这篇文章你就能学会怎么处理音视频时间合并了。
　　在讲解之前我在这里还是简单来说一下代码当中关于koltin的一些基础知识吧，fun setCallback(callback: FFMpegCallback): AudioTrimmer {         this.callback = callback         return this     }
　　这段代码是一个构造方法，kotlin当中跟java的命名是相反的，比如kotlin当中:冒号后面一般是跟的返回值类型，包括参数后面的冒号就是这个变量的类型。class AudioTrimmer private constructor(private val context: Context) {      private var audio: File? = null     private var callback: FFMpegCallback? = null      private var startTime = ＂00:00:00＂     private var endTime = ＂00:00:00＂     private var outputPath = ＂＂     private var outputFileName = ＂＂      fun setFile(originalFiles: File): AudioTrimmer {         this.audio = originalFiles         return this     }      fun setCallback(callback: FFMpegCallback): AudioTrimmer {         this.callback = callback         return this     }      fun setStartTime(startTime: String): AudioTrimmer {         this.startTime = startTime         return this     }      fun setEndTime(endTime: String): AudioTrimmer {         this.endTime = endTime         return this     }      fun setOutputPath(output: String): AudioTrimmer {         this.outputPath = output         return this     }      fun setOutputFileName(output: String): AudioTrimmer {         this.outputFileName = output         return this     }      fun trim() {          if (audio == null || !audio!!.exists()) {             callback!!.onFailure(IOException(＂File not exists＂))             return         }         if (!audio!!.canRead()) {             callback!!.onFailure(IOException(＂Can＂t read the file. Missing permission?＂))             return         }          val outputLocation = Utils.getConvertedFile(outputPath, outputFileName)          //Trim starting from start Time to End time         val cmd = arrayOf(＂-i＂, audio!!.path, ＂-ss＂, startTime, ＂-t＂, endTime, ＂-c＂, ＂copy＂, outputLocation.path)          try {             FFmpeg.getInstance(context).execute(cmd, object : ExecuteBinaryResponseHandler() {                 override fun onStart() {}                  override fun onProgress(message: String?) {                     callback!!.onProgress(message!!)                 }                  override fun onSuccess(message: String?) {                     Utils.refreshGallery(outputLocation.path, context)                     callback!!.onSuccess(outputLocation, OutputType.TYPE_AUDIO)                  }                  override fun onFailure(message: String?) {                     if (outputLocation.exists()) {                         outputLocation.delete()                     }                     callback!!.onFailure(IOException(message))                 }                  override fun onFinish() {                     callback!!.onFinish()                 }             })          } catch (e: Exception) {             callback!!.onFailure(e)         } catch (e2: FFmpegCommandAlreadyRunningException) {             callback!!.onNotAvailable(e2)         }      }      companion object {          val TAG = ＂AudioTrimmer＂          fun with(context: Context): AudioTrimmer {             return AudioTrimmer(context)         }     } }
　　上面的代码也很简单，就是从外部获取一个视频的输入文件，加上开始时间和结束时间来裁剪一个视频的长度。
　　好了如果有不懂得可以评论里面我们一起来讨论。
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