问题
I'm currently using onPreviewCallback so I can capture frames from camera when in preview and stream them via http.
That works but then I issue a command to start recording and, it seems, I do not have a preview callback anymore.
So, how do I keep the preview callback so I can both send the frames from the surface to my server AND record the video on the device?
回答1:
I didn't work for quite long time with Android Camera. However, as I remember
1) onPreviewCallback isn't called while you are recording
It's mentioned in couple of questions:
Camera onPreviewFrame not called How to show real time filtered camera preview while recording videos?
2) I saw that it was handled in SipDroid and couple of other Android SIP clients following way (this was a 1-2 years ago, so this method could be outdates):
- A pipe was created
- Receiving socket of the pipe was wrapped in FileDescriptor and passed to MediaRecorder setOutputFile
- Sending socket of the pipe was constantly read in a thread.
- This way you can receive a content which is written to a file
- Now, the issue how to deal with the content (since, it's H.263 or H.264 encoded and could be mixed with the sound, if you record video with the sound).
- There were some heuristical algorithms which parsed the content (however, it's pain in the ass)
3) You can use onPreviewFrame + start AudioRecorder and encode it yourself (using ffmpeg or something like that) to mp4 file. This way you don't need to start MediaRecorder recording.
回答2:
You can call these methods after your media recorder.start() being called as following :
camera.reconnect();
camera.setPreviewCallback();
surfaceview.getHolder().addCallback();
The reasons:
- After camera.unlock() is called, another process(here is the media recorder process) may use the camera; when the process is done, you must reconnect to the camera, which will re-acquire the lock and allow you to continue using the camera.
- And then re-register the surfaceview frame data callback after camera reconnected, because its some state may be changed after reconnected.
I have ever been the same issue as yours in my application, and i fixed it by this. Hope it can resolve your problems!
回答3:
Once I got the camera and MediaRecorder to start and stop recording without crashing (was not easy) I still had a problem like you described, where the preview callback would stop getting called.
The fix I finally found was adding a call to setPreviewCallback after mediaRecorder.start(), and another after mediaRecorder.stop(). Not sure if this is correct, but it worked on the Razr M I am testing on.
来源：https://stackoverflow.com/questions/16164195/keeping-preview-callback-while-recording-video