Ideally I'd like to accomplish two goals:
Pass the Camera preview data to a MediaCodec encoder via a Surface. I can create the Surface using MediaCodec.createInputSurface() but the Camera.setPreviewDisplay() takes a SurfaceHolder, not a Surface.
In addition to passing the Camera preview data to the encoder, I'd also like to display the preview on-screen (so the user can actually see what they are encoding). If the encoder wasn't involved then I'd use a SurfaceView, but that doesn't appear to work in this scenario since SurfaceView creates its own Surface and I think I need to use the one created by MediaCodec.
I've searched online quite a bit for a solution and haven't found one. Some examples on bigflake.com seem like a step in the right direction but they take an approach that adds a bunch of EGL/SurfaceTexture overhead that I'd like to avoid. I'm hoping there is a simpler example or solution where I can get the Camera and MediaCodec talking more directly without involving EGL or textures.
As of Android 4.3 (API 18), the bigflake CameraToMpegTest approach is the correct way.
The EGL/SurfaceTexture overhead is currently unavoidable, especially for what you want to do in goal #2. The idea is:
Configure the Camera to send the output to a SurfaceTexture. This makes the Camera output available to GLES as an "external texture".
Render the SurfaceTexture to the Surface returned by MediaCodec#createInputSurface(). That feeds the video encoder.
Render the SurfaceTexture a second time, to a GLSurfaceView. That puts it on the display for real-time preview.
The only data copying that happens is performed by the GLES driver, so you're doing hardware-accelerated blits, which will be fast.
The only tricky bit is you want the external texture to be available to two different EGL contexts (one for the MediaCodec, one for the GLSurfaceView). You can see an example of creating a shared context in the "Android Breakout game recorder patch" sample on bigflake -- it renders the game twice, once to the screen, once to a MediaCodec encoder.
Update: This is implemented in Grafika ("Show + capture camera").
Update: The multi-context approach in "show + capture camera" approach is somewhat flawed. The "continuous capture" Activity uses a plain SurfaceView, and is able to do both screen rendering and video recording with a single EGL context. This is recommended.
Related
I don't believe the following as been explicitly answered:
Using the Camera2 API, is it possible to record outside a native device resolution (say, 1:1) without the use of post-processing such as ffmpeg?
You don't have a lot of detail to explain exactly what resolution you want to use, but sounds like you want to record in an aspect ratio/resolution that doesn't match one of the supported aspect ratios/resolutions from the device's camera.
You can always send the image data to the GPU, do whatever cropping/scaling you want there, and then send it on to a video encoder.
Generally, that'd involve:
Setting up an EGL context
Creating a render target in EGL, and getting an Android Surface for it
Creating a SurfaceTexture to send texture data to EGL
Connect EGL input SurfaceTexture to the camera (by first creating a Surface from it, if using camera2)
Connect EGL output Surface to a MediaRecorder
Write shader code to process the incoming frames from camera, crop/scale/modify as needed, then render them to the output surface
Set up camera and media recorder, then start them both
In the SurfaceTexture onFrameAvailable, trigger your rendering code.
This is quite a bit of scaffolding to build, but should be rather efficient when done.
To play a media using Android MediaPlayer or MediaCodec, most of the time, you use SurfaceView or GLSurfaceView (There is another way to achieve this using TextureView, but let's not talk about it here, since it's a bit different type of view)
And as far as I know, capturing the video frame from SurfaceView is not possible - you don't have access to hw overlay.
How about GLSurfaceView? Since we have access to YUV pixels (we're, right?), is it possible?
Can anyone point me where i can find a sample code to do it?
I don't think below explanation can work, because it's assuming the color format is RGBA, and in above case, I think it's YUV.
When using GLES20.glReadPixels on android, the data returned by it is not exactly the same with the living preview
Thank you and have a great day.
You are correct in that you cannot read back from a Surface. It's the producer side of a producer-consumer pair. GLSurfaceView is just a bunch of code wrapped around a SurfaceView that (in theory) makes working with GLES easier.
So you have to send the preview somewhere else. One approach is to send it to a SurfaceTexture, which converts every frame sent to its Surface into a GLES texture. The texture can then be rendered twice, once for display and once to an offscreen pbuffer that can be saved as a bitmap (just like this question).
I'm not sure why you don't want to talk about TextureView. It's a View that uses SurfaceTexture under the hood, and it provides a getBitmap() call that does exactly what you want.
I was able to decode an mp4 video. If I configure the decoder using a Surface I can see the video on screen. Now, I want to edit the frame (adding a yellow line or even better overlapping a tiny image) and encode the video as a new video. It is not necessary to show the video and I don't care now about the performance.(If I show the frames while editing I could have a gap if the editing function takes a lot of time), So, What do you recommend to me, configure the decoder with a GlSurface anyway and use OpenGl (GLES), or configure it with null and somehow convert the Bytebuffer to a Bitmap, modify it, and encode the bitmap as a byte array? Also I saw in Grafika page that you cand use a Surface with a custom Rederer and use OpenGl (GLES). Thanks
You will have to use OpenGLES. ByteBuffer/Bitmap approach can not give realistic performance/features.
Now that you've been able to decode the Video (using MediaExtractor and Codec) to a Surface, you need to use the SurfaceTexture used to create the Surface as an External Texture and render using GLES to another Surface retrieved from MediaCodec configured as an encoder.
Though Grafika doesn't have an exactly similar complete project, you can start with your existing project and then try to use either of the following subprojects in grafika Continuous Camera or Show + capture camera, which currently renders Camera frames (fed to SurfaceTexture) to a Video (and display).
So essentially, the only change is the MediaCodec feeding frames to SurfaceTexture instead of the Camera.
Google CTS DecodeEditEncodeTest does exactly the same and can be used as a reference in order to make the learning curve smoother.
Using this approach, you can certainly do all sorts of things like manipulating the playback speed of video (fast forward and slow-down), adding all sorts of overlays on the scene, play with colors/pixels in the video using shaders etc.
Checkout filters in Show + capture camera for an illustration for the same.
Decode-edit-Encode flow
When using OpenGLES, 'editing' of the frame happens via rendering using GLES to the Encoder's input surface.
If decoding and rendering+encoding are separated out in different threads, you're bound to skip a few frames every frame, unless you implement some sort of synchronisation between the two threads to keep the decoder waiting until the render+encode for that frame has happened on the other thread.
Although modern hardware codecs support simultaneous video encoding and decoding, I'd suggest, do the decoding, rendering and encoding in the same thread, especially in your case, when the performance is not a major concern right now. That will help avoiding the problems of having to handle synchronisation on your own and/or frame jumps.
I am referring to the demo app Grafika, in which the CameraCaptureActivity records a video while showing a live preview of the effects applied.
While recording in the CameraCaptureActivity, any effect that is applied to the frame that comes from the camera is done twice.
Once for the preview and once while saving the video to the file.
Since the same frame that is previewed is being saved to the file, it would save a lot of processing if this could be done just once.
The rendering of the frames happens directly on the two surfaces, one being the GLSurfaceView (for preview) and the other being MediaCodec (saving part).
Is there a way to render the OpenGL effect only once?
If I could copy the contents of one surface to the other it would be great.
Is there a way to do this?
Yes: you can render to an FBO, then blit the output twice, once for display and once for recording.
Grafika's "record GL app" activity demonstrates three different approaches to the problem (one of which only works on GLES 3.0+). The doFrame() method does the work; the draw-once-blit-twice approach is currently here.
I am using MediaCodec's decoder to output data to a surface. Using the .configure function, I passed a surface created through surfaceComposerClient. The problem is that the codec fails to start. I presume this is an issue with the way my surface is setup (when I set surface to NULL the codec starts)
Looking at MediaCodec decoder java examples it seems like I need to create an EGL backed SurfaceTexture. Is it possible to natively create a surface texture using C++/NDK? Are there any examples out there of this?
I assume this is not a "normal" app, since you're interacting with SurfaceFlinger directly.
You can find examples in some internal OpenGL tests -- the code was fixed up for the 5.0 Lollipop release. Take a look at the San Angeles demo, which uses the WindowSurface class to get a surface from SurfaceComposerClient.
You don't need a SurfaceTexture, or do anything with EGL, to decode a video to a surface. Surfaces have a producer-consumer structure, and EGL and MediaCodec are two different examples of producers. (SurfaceFlinger is the consumer.)
It's never easy to know why MediaCodec is failing. You can try drawing on the surface with GLES to see if it's valid, but my guess is that your problem is elsewhere.
For a SurfaceTexture, the app is both the producer and the consumer; it provides a way to decode the video to a surface that you can then manipulate as a GLES texture. This adds unnecessary overhead if you just want the video to play on screen.
refer to SimplePlayer.h&.cpp in Android-4.4 source code. it's used to decode an media file and output decoded video into surface. i think it is similar with your scenario.