Creating an ImageWriter into a SurfaceTexture with a format of choice

[micjan]

I'm trying to wrap an ImageWriter around a SurfaceTexture with a format set to the one I need.

mCreatedGPUSurface = new Surface(new SurfaceTexture(0));
setFormat(mCreatedGPUSurface, 640, 380, ImageFormat.YUV_420_888);
mImageWriter = ImageWriter.newInstance(mCreatedGPUSurface, 3);
Log.i("basicmediadecoder", "writer format: " + mImageWriter.getFormat());

setFormat is a native method in which I want to set the format of the Surface:

extern "C"
JNIEXPORT void JNICALL
Java_com_example_android_basicmediadecoder_MainActivity_setFormat(JNIEnv *env, jobject instance,
                                                                  jobject surface, jint width,
                                                                  jint height, jint format) {

    ANativeWindow *window = NULL;
    window = ANativeWindow_fromSurface(env, surface);

    if (window != NULL) {
        ANativeWindow_setBuffersGeometry(window, width, height, format);
        int format = ANativeWindow_getFormat(window);
        __android_log_print(ANDROID_LOG_INFO, "basicmediadecoder", "window format 0x%x",
                            format);
        ANativeWindow_release(window);
    } else {
        __android_log_print(ANDROID_LOG_INFO, "basicmediadecoder", "error getting a window");
    }

}

Looking in logcat, I'm getting the expected YUV format from the native function, but mImageWriter.getFormat() returns 1 (RGBA_8888) and not the expected YUV format:

06-18 11:48:22.420 16198-16198/com.example.android.basicmediadecoder I/basicmediadecoder: window format 0x23

    window format 0x23

06-18 11:48:22.421 16198-16198/com.example.android.basicmediadecoder I/basicmediadecoder: writer format: 1

Any clues? Is this not possible?

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