cwac-camera 库具有在保存照片之前调用的事件挂钩:
@Override public void saveImage(PictureTransaction xact, byte[] image) {}
我是否只是忽略了这一点,或者是否没有接收器告诉我视频文件何时被保存?
更多背景信息:有两种方式结束视频。一种是通过调用
.stopRecording();
另一种是通过配置记录器的最大持续时间/最大文件大小(在这种情况下,无需显式调用 stop Recording() 即可停止记录:
recorder.setMaxDuration()
在我看来,在这两种情况下,Android 都需要大约 100 到 200 毫秒才能完成文件。由于我刚使用时视频文件经常损坏
mediaRecorder.setOnInfoListener(new MediaRecorder.OnInfoListener() {
@Override public void onInfo(MediaRecorder mr, int what, int extra) {}
}
检测它何时完成或尝试在调用停止 Recording() 后立即读取它。我尝试使用 FileObserver 来检测媒体记录器何时实际关闭文件,效果很好。
我想讨论一下这个问题,如果有人有同样的经历,以及是否有一种方法可以让 CWAC-Camera 检测并发出录制文件的信号。
--
我刚刚在 Android 文档中跳过了这个http://developer.android.com/reference/android/media/MediaRecorder.html#setMaxDuration(int) http://developer.android.com/reference/android/media/MediaRecorder.html#setMaxDuration(int)
“停止是异步发生的,不能保证录音机在通知侦听器时已经停止。”
这解释了为什么文件有时没有正确关闭,并且隐含地意味着使用 FileObserver 可能是在写入文件后访问文件的唯一安全且有效的方法。
所以我们需要这样的东西来检测事件。
@Override protected File getVideoPath() {
File file = super.getVideoPath(); // assemble the video path
fileObserverPath = file.getAbsolutePath();
fileObserver = new FileObserver(fileObserverPath, FileObserver.CLOSE_WRITE) {
@Override public void onEvent(int event, String videoPath) {
System.out.println("**** CameraHost: write closed");
if (fileObserver != null) { // defensive
fileObserver.stopWatching();
fileObserver = null;
}
// process the file here
}
};
fileObserver.startWatching();
return file;
}
--
我继续将以下代码添加到我的 CameraHost 中以获取计时:
@Override public void configureRecorderOutput(int cameraId, MediaRecorder recorder) {
System.out.println("**** CameraHost: configureRecorderOutput");
recorder.setMaxDuration(Constants.FRAMEPLAYER_MAX_RECORDING_LENGTH_PER_FRAME_MSEC);
recorder.setOnInfoListener(new MediaRecorder.OnInfoListener() {
@Override public void onInfo(MediaRecorder mr, int what, int extra) {
switch (what) {
case MediaRecorder.MEDIA_RECORDER_INFO_MAX_DURATION_REACHED: {
System.out.println("**** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED");
break;
}
}
}
});
super.configureRecorderOutput(cameraId, recorder);
}
Timings:
11-20 07:33:28.974 32602-32602/cc.closeup.android I/System.out﹕ **** CameraHost: configureRecorderOutput
11-20 07:33:31.064 32602-32602/cc.closeup.android I/System.out﹕ **** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED
11-20 07:33:31.084 32602-32602/cc.closeup.android I/System.out﹕ **** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED
11-20 07:33:36.914 32602-32655/cc.closeup.android I/System.out﹕ **** CameraHost: write closed
11-20 07:33:36.914 32602-32655/cc.closeup.android I/System.out﹕ **** CameraHost: write closed
有两件事很奇怪:
- MEDIA_RECORDER_INFO_MAX_DURATION_REACHED 被引发,但录制不会停止。与 Android 文档中指定的相反,我必须显式调用 stop。
- 尽管 configureRecorderOutput 仅引发一次,但我的侦听器被调用两次。我尝试了相同的外部 CWAC 摄像头,但听众只被调用一次。
不确定我是否在某个地方犯了错误,或者 CWAC 相机出了什么问题。
有人来评论一下吗?
--
关于2.,无论是什么,我的日志显示触发事件的媒体记录器是相同的,并且在what=800(MEDIA_RECORDER_INFO_MAX_DURATION_REACHED)之后不久,引发了未记录的what=536871912。第二次引发该事件时,未记录的 What=268436456。
[来自华硕 Memo Pad 7:]
11-20 09:41:25.748 3398-3398/cc.closeup.android I/System.out﹕ **** CameraHost: onInfo: mr = android.media.MediaRecorder@41c9da88, what = 800, extra 0
11-20 09:41:25.748 3398-3398/cc.closeup.android I/System.out﹕ **** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED
11-20 09:41:25.748 3398-3398/cc.closeup.android I/System.out﹕ **** CameraHost: onInfo: mr = android.media.MediaRecorder@41c9da88, what = 536871912, extra 0
11-20 09:41:25.778 3398-3398/cc.closeup.android I/System.out﹕ **** CameraHost: onInfo: mr = android.media.MediaRecorder@41c9da88, what = 800, extra 0
11-20 09:41:25.778 3398-3398/cc.closeup.android I/System.out﹕ **** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED
11-20 09:41:25.778 3398-3398/cc.closeup.android I/System.out﹕ **** CameraHost: onInfo: mr = android.media.MediaRecorder@41c9da88, what = 268436456, extra 0
我在另一台设备上运行了这个,其中 MEDIA_RECORDER_INFO_MAX_DURATION_REACHED 事件也引发了两次,但是未记录的什么=?根本没有提高。供应商具体实施?
[来自三星 Galaxy Note 2:]
11-20 09:46:42.711 25699-25699/cc.closeup.android I/System.out﹕ **** CameraHost: onInfo: mr = android.media.MediaRecorder@42831c30, what = 800, extra 0
11-20 09:46:42.711 25699-25699/cc.closeup.android I/System.out﹕ **** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED
11-20 09:46:42.776 25699-25699/cc.closeup.android I/System.out﹕ **** CameraHost: onInfo: mr = android.media.MediaRecorder@42831c30, what = 800, extra 0
11-20 09:46:42.776 25699-25699/cc.closeup.android I/System.out﹕ **** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED
我继续发帖...
--
关于1.,录制实际上已停止(录制的文件长一秒),但FileObserver()显然只是在很晚之后才被调用,即在我显式调用cameraView.stop()之后。
我尝试直接在事件中传递的 MediaRecorder 上调用 stop() ,这在 Android 中有效,但在 CWAC 中无效。
--
关于1.,我进一步深入研究了这一点,看起来视频文件一直被写入,直到我显式调用cameraView.stop() - 然后它才会被截断为一秒并关闭。
// startRecording() called here
11-20 11:29:49.072 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:49.072 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 32, videoPath = media0.mp4
11-20 11:29:49.082 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:49.082 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:49.082 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:49.082 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:49.082 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:49.082 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.132 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.132 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.132 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.132 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.132 4987-4987/cc.closeup.android I/System.out﹕ **** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED
11-20 11:29:51.142 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.142 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.142 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.142 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.142 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
(...)
11-20 11:29:51.182 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.182 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.182 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.192 4987-4987/cc.closeup.android I/System.out﹕ **** CameraHost: MEDIA_RECORDER_INFO_MAX_DURATION_REACHED
11-20 11:29:51.192 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.192 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.192 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.192 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.192 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
(...)
11-20 11:29:51.252 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.262 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.262 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.262 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.262 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:51.262 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
// stopRecording() called here
11-20 11:29:52.492 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.492 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.492 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.492 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.572 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.572 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.572 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.572 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.572 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.572 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.572 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
(...)
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 2, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: FileObserver: onEvent: event = 8, videoPath = media0.mp4
11-20 11:29:52.582 4987-5167/cc.closeup.android I/System.out﹕ **** CameraHost: write closed: videoPath = media0.mp4