docs: public void drawFrame(int textureId, float[] texMatrix) {
          // Use the identity matrix for MVP so our 2x2 FULL_RECTANGLE covers the viewport.
          synchronized (mDrawLock) {
              if (mCorrectVerticalVideo && !mScaleToFit && (requestedOrientation == SCREEN_ROTATION.VERTICAL || requestedOrientation == SCREEN_ROTATION.UPSIDEDOWN_VERTICAL)) {
                  Matrix.scaleM(texMatrix, 0, 0.316f, 1.0f, 1f);
              }
              mProgram.draw(IDENTITY_MATRIX, mRectDrawable.getVertexArray(), 0,
                      mRectDrawable.getVertexCount(), mRectDrawable.getCoordsPerVertex(),
                      mRectDrawable.getVertexStride(),
                      texMatrix, TEX_COORDS_BUF, textureId, TEX_COORDS_STRIDE);
          }
      }