2023-10-17 15:38:39 CST W42D2

examples/scaling-video/main.go

@@ -1,5 +1,115 @@
 package main
 
-func main() {
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
 
+	ffmpeg "github.com/qrtc/ffmpeg-dev-go"
+)
+
+func fillYuvImage(data [4]*uint8, linesize [4]int32, width, height, frameIndex int32) {
+	// Y
+	data0 := unsafe.Slice(data[0], height*linesize[0]+width)
+	for y := int32(0); y < height; y++ {
+		for x := int32(0); x < width; x++ {
+			data0[y*linesize[0]+x] = (uint8)(x + y + frameIndex*3)
+		}
+	}
+
+	// Cb and Cr
+	data1 := unsafe.Slice(data[1], height*width/4)
+	data2 := unsafe.Slice(data[2], height*width/4)
+	for y := int32(0); y < height/2; y++ {
+		for x := int32(0); x < width/2; x++ {
+			data1[y*linesize[1]+x] = (uint8)(128 + y + frameIndex*2)
+			data2[y*linesize[2]+x] = (uint8)(64 + x + frameIndex*5)
+		}
+	}
+}
+
+func main() {
+	var ret int32
+	var dstBufsize int32
+	var srcW int32 = 320
+	var srcH int32 = 240
+	var dstW, dstH int32
+	var srcData, dstData [4]*uint8
+	var srcLinesize, dstLinesize [4]int32
+	var srcPixFmt = ffmpeg.AV_PIX_FMT_YUV420P
+	var dstPixFmt = ffmpeg.AV_PIX_FMT_RGB24
+
+	if len(os.Args) != 3 {
+		fmt.Fprintf(os.Stderr, "Usage: %s output_file output_size\n"+
+			"API example program to show how to scale an image with libswscale.\n"+
+			"This program generates a series of pictures, rescales them to the given "+
+			"output_size and saves them to an output file named output_file\n."+
+			"\n", os.Args[0])
+		os.Exit(1)
+	}
+	dstFilename := os.Args[1]
+	dstSize := os.Args[2]
+
+	if ret = ffmpeg.AvParseVideoSize(&dstW, &dstH, dstSize); ret < 0 {
+		fmt.Fprintf(os.Stderr,
+			"Invalid size '%s', must be in the form WxH or a valid size abbreviation\n", dstSize)
+		os.Exit(1)
+	}
+
+	dstFile, err := os.OpenFile(dstFilename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Could not open %s\n", dstFilename)
+		os.Exit(1)
+	}
+
+	// create scaling context
+	swsCtx := ffmpeg.SwsGetContext(srcW, srcH, srcPixFmt,
+		dstW, dstH, dstPixFmt,
+		ffmpeg.SWS_BILINEAR, nil, nil, nil)
+	if swsCtx == nil {
+		fmt.Fprintf(os.Stderr, "Impossible to create scale context for the conversion "+
+			"fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
+			ffmpeg.AvGetPixFmtName(srcPixFmt), srcW, srcH,
+			ffmpeg.AvGetPixFmtName(dstPixFmt), dstW, dstH)
+		ret = ffmpeg.AVERROR(int32(syscall.EINVAL))
+		goto end
+	}
+
+	// allocate source and destination image buffers
+	if ret = ffmpeg.AvImageAlloc(srcData[:], srcLinesize[:], srcW, srcH, srcPixFmt, 16); ret < 0 {
+		fmt.Fprintf(os.Stderr, "Could not allocate source image\n")
+		goto end
+	}
+
+	// buffer is going to be written to rawvideo file, no alignment
+	if ret = ffmpeg.AvImageAlloc(dstData[:], dstLinesize[:], dstW, dstH, dstPixFmt, 1); ret < 0 {
+		fmt.Fprintf(os.Stderr, "Could not allocate destination image\n")
+		goto end
+	}
+	dstBufsize = ret
+
+	for i := int32(0); i < 100; i++ {
+		// generate synthetic video
+		fillYuvImage(srcData, srcLinesize, srcW, srcH, i)
+
+		// convert to destination format
+		ffmpeg.SwsScale(swsCtx, srcData[:], srcLinesize[:], 0, srcH, dstData[:], dstLinesize[:])
+
+		// write scaled image to file
+		dstFile.Write(unsafe.Slice(dstData[0], dstBufsize))
+	}
+
+	fmt.Fprintf(os.Stderr, "Scaling succeeded. Play the output file with the command:\n"+
+		"ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
+		ffmpeg.AvGetPixFmtName(dstPixFmt), dstW, dstH, dstFilename)
+
+end:
+	dstFile.Close()
+	ffmpeg.AvFreep(unsafe.Pointer(&srcData[0]))
+	ffmpeg.AvFreep(unsafe.Pointer(&dstData[0]))
+	ffmpeg.SwsFreeContext(swsCtx)
+	if ret < 0 {
+		os.Exit(1)
+	}
 }