Menu
I created a movie player based on FFmpeg. It works fine. The decoding is quite fast, on LG P970 (Cortex A8 with Neon) I have an average 70 fps with 640 x 424 resolution video stream including YUV2RGB conversion. However, there is one bottleneck. It is drawing on Canvas.
I use jnigraphics native library to fill picture data into the bitmap in the native side and then I draw this bitmap on Canvas in SurfaceView. It is quite simple and common approach, but the drawing takes 44 ms for bitmap with 640 x 424 resolution which reduces fps to 23 and makes this technique unusable... It takes a lot more then the whole A/V frame decoding!
Is there any method how to draw bitmaps significantly faster? I would prefer to render completely in the native code using OpenGLES 2, but I have read it also could be slow. So what now?...
How can I render bitmaps as fast as possible?
457
Choose the most appropriate decode method based on your image data source. These methods attempt to allocate memory for the constructed bitmap and therefore can easily result in an OutOfMemory exception. Each type of decode method has additional signatures that let you specify decoding options via the BitmapFactory.
The Bitmap class has many methods that allow us to create an instance of a Bitmap by using java . These methods will allow us to set the width , height , density , and number of pixels of a Bitmap .
View mImg = findViewById(R. id. image_from_gallery); ((ImageView) mImg). setImageBitmap(bitmap);
The recycle() method allows an app to reclaim memory as soon as possible. Caution: You should use recycle() only when you are sure that the bitmap is no longer being used. If you call recycle() and later attempt to draw the bitmap, you will get the error: "Canvas: trying to use a recycled bitmap" .
Draw them in GLES1.x. You do not need to use GLES2 as you will have no use, or at least not in the context of your question, for shaders which would be the general primary reason of using GLES2.x. So for simplicity sake, GLES1.x would be ideal. All you need to do is draw the bytebuffer to the screen. On my Galaxy S (Vibrant) this takes about 3ms. The size of the byte[] in my wallpaper is 800x480x3 or 1152000 which is significantly larger than what you are working with.
I believe this guide should point you in the correct direction.
http://qdevarena.blogspot.com/2009/02/how-to-load-texture-in-android-opengl.html
As for the notion of accessing canvas from native code, I would just avoid that altogether and follow an OpenGL implementation by offloading everything to GPU as much as possible.
78
I recall during the Replica Island presentation during GoogleIO the designer said that using the OpenGL 'draw_texture' extension glDrawTexfOES was the fastest way to blit to the screen, and significantly faster than drawing just regular quads with textures attached (I'm assuming you're using OpenGL).
You can't rotate the texture, but it doesn't sound like you need that.
26
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
