Dmitry Sergeev
64 lines
1.8 KiB
Go
64 lines
1.8 KiB
Go
package generator
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import "fmt"
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// V210AGenerator combines a v210 fill generator with a packed 10-bit alpha
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// plane. It owns the fill generator and closes it from Close.
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type V210AGenerator struct {
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fill FrameGenerator
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width int
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height int
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fillSize int
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alphaBase []byte
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}
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var _ FrameGenerator = (*V210AGenerator)(nil)
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func NewV210AGenerator(
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fill FrameGenerator,
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width, height uint,
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) (*V210AGenerator, error) {
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if fill == nil {
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return nil, fmt.Errorf("v210a: fill generator is nil")
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}
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if width == 0 || height == 0 {
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return nil, fmt.Errorf("v210a: width and height must be greater than zero, got %dx%d", width, height)
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}
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if width%2 != 0 {
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return nil, fmt.Errorf("v210a: width must be even for 4:2:2 video, got %d", width)
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}
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g := &V210AGenerator{
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fill: fill,
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width: int(width),
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height: int(height),
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fillSize: V210FrameSize(int(width), int(height)),
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alphaBase: make([]byte, AlphaFrameSize(int(width), int(height))),
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}
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if err := fillAlphaPlane(g.alphaBase, g.width, g.height, alphaOpaque); err != nil {
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return nil, fmt.Errorf("v210a: initialize alpha plane: %w", err)
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}
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return g, nil
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}
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func (g *V210AGenerator) GenerateFrame(dst []byte, frameIndex int) error {
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need := V210AFrameSize(g.width, g.height)
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if len(dst) < need {
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return fmt.Errorf("v210a: destination is too small: got %d bytes, need %d", len(dst), need)
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}
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if err := g.fill.GenerateFrame(dst[:g.fillSize], frameIndex); err != nil {
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return fmt.Errorf("v210a: generate fill frame %d: %w", frameIndex, err)
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}
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alpha := dst[g.fillSize:need]
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copy(alpha, g.alphaBase)
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if err := patchAlphaMovingSquare(alpha, g.width, g.height, frameIndex); err != nil {
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return fmt.Errorf("v210a: patch alpha frame %d: %w", frameIndex, err)
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}
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return nil
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}
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func (g *V210AGenerator) Close() error {
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return g.fill.Close()
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}
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