Process image with android opengl es but output image is weird in a certain device

Question

I wrote a demo about camera which is similar to ContinuousCaptureActivity of grafika (Source code of ContinuousCaptureActivity.java). For every frame, I added some operations besides drawing the frame to screen.

I create a fbo, then bind it and draw the frame to the fbo. In order to check the image rendered to the fbo, I read back the image data back to RAM using pbo and save the image as jpg every 50 frames. In this way, I got the jpg file but it was scaled, picture is as follows:

I supposed the matrix from SurfaceTexture caused the scaling because every drawFrame() applied that matrix.So I created anothter fbo and draw the frame of the first fbo to this fbo, then I save the image as jpg and the image turn OK as expected. Look at this one:

So the conclusion is that 2 draws will restore the image correctly.

But the image is weird in a huawei phone of mine(model:huawei MT7-CL00). Look at it:

I have checked the image of the first fbo with the huawei phone, it is scaled as expected but not weird. So I think the error ocurred in the scecond fbo. But I can not figure out the reason. Who can give me some advices?

Some source codes:

fbo definitions:

private GlTexture mGlTexture;
private GlFrameBuffer mGlFrameBuffer;
private GlFrameBuffer mGlFrameBuffer1;

GlTexture and GlFrameBuffer class source codes:

http://www.paste.org/80680

bindFbo method:

private void bindFBO(int fbo)
{
    GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, fbo);
    GLES20.glClearColor(0.0F, 0.0F, 0.0F, 0.0F);
    GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
    SurfaceView sv = (SurfaceView) findViewById(R.id.continuousCapture_surfaceView);
    GLES20.glViewport(0, 0, 640, 480);
}

the key codes in drawFrame():

            mDisplaySurface.makeCurrent();
    mCameraTexture.updateTexImage();
    mCameraTexture.getTransformMatrix(mTmpMatrix);

    // Fill the SurfaceView with it.
    SurfaceView sv = (SurfaceView) findViewById(R.id.continuousCapture_surfaceView);
    int viewWidth = 640;
    int viewHeight = 480;
    GLES20.glViewport(0, 0, viewWidth, viewHeight);
    mFullFrameBlit.drawFrame(mTextureId, mTmpMatrix);
    //drawExtra(mFrameNum, viewWidth, viewHeight);
    mDisplaySurface.swapBuffers();


    bindFBO(mGlFrameBuffer.getID());
    mFullFrameBlit.drawFrame(mTextureId, mTmpMatrix);
    bindFBO(mGlFrameBuffer1.getID());
    mFullFrameBlit2d.drawFrame(mGlTexture.getID(), mTmpMatrix);

    String filename = "/sdcard/test/" + System.currentTimeMillis() + ".jpg";
    new File(filename).getParentFile().mkdirs();
    if (mFrameNum % 50 == 0)
    {
        try {
            getPixelFromPBO(viewWidth, viewHeight, filename);
        } 
        catch (Exception e) {
        }
    }