video.go

package main

import (
	"fmt"
	"image"
	"log"
	"os"

	"github.com/3d0c/gmf"
	"github.com/tfriedel6/canvas"
	"github.com/tfriedel6/canvas/sdlcanvas"
)

func main() {
	if len(os.Args) <= 1 {
		fmt.Println("Need video file name as command line parameter")
		return
	}

	wnd, cv, err := sdlcanvas.CreateWindow(1280, 720, "Canvas Test")
	if err != nil {
		log.Println(err)
		return
	}
	defer wnd.Destroy()

	inputCtx, err := gmf.NewInputCtx(os.Args[1])
	if err != nil {
		panic(err)
	}
	defer inputCtx.CloseInputAndRelease()

	srcVideoStream, err := inputCtx.GetBestStream(gmf.AVMEDIA_TYPE_VIDEO)
	if err != nil {
		panic(fmt.Sprint("No video stream found in", os.Args[1]))
	}

	codec, err := gmf.FindEncoder(gmf.AV_CODEC_ID_RAWVIDEO)
	if err != nil {
		panic(err)
	}

	cc := gmf.NewCodecCtx(codec)
	defer gmf.Release(cc)

	cc.SetTimeBase(gmf.AVR{Num: 1, Den: 1})

	// This should really be AV_PIX_FMT_RGB32, but then red and blue channels are switched
	cc.SetPixFmt(gmf.AV_PIX_FMT_BGR32).SetWidth(srcVideoStream.CodecCtx().Width()).SetHeight(srcVideoStream.CodecCtx().Height())
	if codec.IsExperimental() {
		cc.SetStrictCompliance(gmf.FF_COMPLIANCE_EXPERIMENTAL)
	}

	if err := cc.Open(nil); err != nil {
		panic(err)
	}

	swsCtx := gmf.NewSwsCtx(srcVideoStream.CodecCtx(), cc, gmf.SWS_BICUBIC)
	defer gmf.Release(swsCtx)

	dstFrame := gmf.NewFrame().
		SetWidth(srcVideoStream.CodecCtx().Width()).
		SetHeight(srcVideoStream.CodecCtx().Height()).
		SetFormat(gmf.AV_PIX_FMT_BGR32) // see above
	defer gmf.Release(dstFrame)

	if err := dstFrame.ImgAlloc(); err != nil {
		panic(err)
	}

	ist, err := inputCtx.GetStream(srcVideoStream.Index())
	if err != nil {
		panic(err)
	}
	defer gmf.Release(ist)

	codecCtx := ist.CodecCtx()
	defer gmf.Release(codecCtx)

	nextFrame := true
	wnd.KeyDown = func(scancode int, rn rune, name string) {
		nextFrame = true
	}

	vidImg, _ := canvas.LoadImage(nil)

	wnd.MainLoop(func() {
		cv.ClearRect(0, 0, 1280, 720)

		if nextFrame {
			// nextFrame = false
			for packet := range inputCtx.GetNewPackets() {
				if packet.StreamIndex() != srcVideoStream.Index() {
					// skip non video streams
					continue
				}

				frame, err := packet.Frames(codecCtx)
				if err != nil {
					fmt.Println(err)
					break
				}
				swsCtx.Scale(frame, dstFrame)

				p, err := dstFrame.Encode(cc)
				if err != nil {
					fmt.Println(err)
					break
				}

				width, height := frame.Width(), frame.Height()
				img := new(image.RGBA)
				img.Pix = p.Data()
				img.Stride = 4 * width // 4 bytes per pixel (RGBA), width times per row
				img.Rect = image.Rect(0, 0, width, height)
				vidImg.Replace(img)

				gmf.Release(p)

				gmf.Release(frame)

				gmf.Release(packet)

				break
			}
		}

		cv.DrawImage(vidImg, 0, 0)
	})
}