Method GetFrame

src/effects/Deinterlace.cpp:49–96

This method is required for all derived classes of EffectBase, and returns a modified openshot::Frame object

// This method is required for all derived classes of EffectBase, and returns a
// modified openshot::Frame object
std::shared_ptr<openshot::Frame> Deinterlace::GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number)
{
	// Get original size of frame's image
	int original_width = frame->GetImage()->width();
	int original_height = frame->GetImage()->height();

	// Access the current QImage and its raw pixel data
	auto image           = frame->GetImage();
	const unsigned char* pixels = image->bits();
	int line_bytes       = image->bytesPerLine();

	// Decide whether to copy even lines (start = 0) or odd lines (start = 1)
	int start = isOdd ? 1 : 0;

	// Compute how many rows we will end up copying
	// If start = 0, rows_to_copy = ceil(original_height / 2.0)
	// If start = 1, rows_to_copy = floor(original_height / 2.0)
	int rows_to_copy = (original_height - start + 1) / 2;

	// Create a new image with exactly 'rows_to_copy' scanlines
	QImage deinterlaced_image(
		original_width,
		rows_to_copy,
		QImage::Format_RGBA8888_Premultiplied
	);
	unsigned char* deinterlaced_pixels = deinterlaced_image.bits();

	// Copy every other row from the source into the new image
	// Parallelize over 'i' so each thread writes to a distinct slice of memory
#pragma omp parallel for
	for (int i = 0; i < rows_to_copy; i++) {
		int row = start + 2 * i;
		const unsigned char* src = pixels + (row * line_bytes);
		unsigned char* dst       = deinterlaced_pixels + (i * line_bytes);
		memcpy(dst, src, line_bytes);
	}

	// Resize deinterlaced image back to original size, and update frame's image
	image = std::make_shared<QImage>(deinterlaced_image.scaled(
		original_width, original_height,
		Qt::IgnoreAspectRatio, Qt::FastTransformation));

	// Update image on frame
	frame->AddImage(image);

	// return the modified frame
	return frame;
}

// Generate JSON string of this object
std::string Deinterlace::Json() const {