Editing android VideoView frames

Question

Environment:

Nexus 7 Jelly Bean 4.1.2

Problem:

I'm trying to make a Motion Detection application that works with RTSP using VideoView.

I wish that there was something like an onNewFrameListener

videoView.onNewFrame(Frame frame)

I've tried to get access to the raw frames of an RTSP stream via VideoView but couldn't find any support for that in the Android SDK.

I found out that VideoView encapsulates the Android's MediaPlayer class.

So i dived into the media_jni lib to try and find a way to access the raw frames, But couldn't find the byte buffer or whatever that represents a frame.

Question:

Anyone has an idea where or how can i find this buffer and get access to it ?

Or any other idea of implementing a Motion Detection over a VideoView ?

Even if it's sais that i need to recompile the AOSP.

Yes, but if i need an earlier version i can manage that too. — Danpe
– Danpe, Commented Nov 27, 2012 at 8:47

halfer · Accepted Answer · 2019-04-26 20:56:46Z

You can extend the VideoView and override its draw(Canvas canvas) method.

Set your bitmap to the canvas received through draw.
Call super.draw() which will get the frame drawn onto your bitmap.

Access the frame pixels from the bitmap.

class MotionDetectorVideoView extends VideoView { public Bitmap mFrameBitmap; ... @Override public void draw(Canvas canvas) { // set your own member bitmap to canvas.. canvas.setBitmap(mFrameBitmap); super.draw(canvas); // do whatever you want with mFrameBitmap. It now contains the frame. ... // Allocate `buffer` big enough to hold the whole frame. mFrameBitmap.copyPixelsToBuffer(buffer); ... } }

I don't know whether this will work. Avoid doing heavy calculation in draw, start a thread there.

How can i get raw pixels of the drawn canvas ? couldn't find anything in their API about it.
There is public void copyPixelsToBuffer (Buffer dst) in Bitmap class. documentation here : developer.android.com/reference/android/graphics/…
You already have the bitmap reference in mFrameBitmap.. Create the bitmap in constructor.. See the edit above..
So you say that when i call super.draw(canvas) it draws on the current bitmap and not replacing with a new one ? And I'm able to call NDK calculation inside draw ?

JasJar · Accepted Answer · 2012-11-30 12:10:21Z

In your case I would use the Camera Preview instead the VideoView, if you are working with live motion, not recorded videos. You can use a Camera Preview Callback to catch everyframe captured by your camera. This callback implements :

onPreviewFrame(byte[] data, Camera camera) Called as preview frames are displayed.

Which I think it could be useful for you.

http://developer.android.com/reference/android/hardware/Camera.PreviewCallback.html

Tell if that is what you are searching for.

Good luck.

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