func lockTexture(tex *sdl.Texture, width int, height int) (pixels []Pixel, pitch int) {
var data unsafe.Pointer
err := tex.Lock(nil, &data, &pitch)
if err != nil {
fmt.Fprintf(os.Stderr, "tex.Lock: %v", err)
panic(err)
}
// Convert pitch units from byte to pixels
pitch /= 4
pixels = sliceFromPixelPtr(data, width*height)
return
}
func play(seq *video.VideoSequence) {
var window *sdl.Window
var renderer *sdl.Renderer
var texture *sdl.Texture
var err error
window, err = sdl.CreateWindow(winTitle,
sdl.WINDOWPOS_UNDEFINED, sdl.WINDOWPOS_UNDEFINED,
winWidth, winHeight,
sdl.WINDOW_SHOWN)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to create window: %s\n", err)
os.Exit(1)
}
defer window.Destroy()
renderer, err = sdl.CreateRenderer(window, -1, sdl.RENDERER_ACCELERATED)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to create renderer: %s\n", err)
os.Exit(2)
}
defer renderer.Destroy()
seq.AlignTo(video.SequenceHeaderStartCode)
var pointer unsafe.Pointer
var pitch int
var yLen int
var cLen int
sdl.Delay(1000)
renderer.Present()
for {
img, err := seq.Next()
if err == io.EOF {
break
}
if err != nil {
fmt.Fprintf(os.Stderr, "Decoding error: %s\n", err)
os.Exit(3)
}
if texture == nil {
w, h := seq.Size()
yLen = w * h
cLen = (w * h) >> 2
texture, err = renderer.CreateTexture(sdl.PIXELFORMAT_IYUV, sdl.TEXTUREACCESS_STREAMING, w, h)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to create texture: %s\n", err)
os.Exit(4)
}
defer texture.Destroy()
}
{
texture.Lock(nil, &pointer, &pitch)
// Convert pointer to []uint8
pixels := *(*[]uint8)(unsafe.Pointer(&reflect.SliceHeader{
Data: uintptr(pointer),
Len: yLen + 2*cLen,
Cap: yLen + 2*cLen,
}))
// Select color planes
y := pixels[0:yLen]
cb := pixels[yLen : yLen+cLen]
cr := pixels[yLen+cLen : yLen+cLen+cLen]
// Copy image data into texture
copy(y, img.Y)
copy(cb, img.Cb)
copy(cr, img.Cr)
texture.Unlock()
}
err = renderer.Copy(texture, nil, nil)
if err != nil {
fmt.Fprintf(os.Stderr, "Copy failed: %s\n", err)
os.Exit(5)
}
renderer.Present()
}
}