2023-10-13 20:52:26 CST W41D5

examples/encode-video/main.go

@@ -0,0 +1,158 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
+
+	ffmpeg "github.com/qrtc/ffmpeg-dev-go"
+)
+
+func encode(encCtx *ffmpeg.AvCodecContext, frame *ffmpeg.AvFrame, pkt *ffmpeg.AvPacket, outfile *os.File) {
+	if frame != nil {
+		fmt.Fprintf(os.Stdout, "Send frame %3d\n", frame.GetPts())
+	}
+
+	ret := ffmpeg.AvCodecSendFrame(encCtx, frame)
+	if ret < 0 {
+		fmt.Fprintf(os.Stderr, "Error sending a frame for encoding\n")
+		os.Exit(1)
+	}
+
+	for ret >= 0 {
+		ret = ffmpeg.AvCodecReceivePacket(encCtx, pkt)
+		if ret == ffmpeg.AVERROR(int32(syscall.EAGAIN)) || ret == ffmpeg.AVERROR_EOF {
+			return
+		} else if ret < 0 {
+			fmt.Fprintf(os.Stderr, "Error during encoding\n")
+			os.Exit(1)
+		}
+
+		fmt.Fprintf(os.Stdout, "Write packet %3d (size=%5d)\n", pkt.GetPts(), pkt.GetSize())
+		outfile.Write(unsafe.Slice(pkt.GetData(), pkt.GetSize()))
+		ffmpeg.AvPacketUnref(pkt)
+	}
+}
+
+func main() {
+	endcode := []uint8{0x00, 0x00, 0x01, 0xb7}
+	if len(os.Args) <= 2 {
+		fmt.Fprintf(os.Stdout, "Usage: %s <output file> <codec name>\n", os.Args[0])
+		os.Exit(1)
+	}
+	filename := os.Args[1]
+	codecName := os.Args[2]
+
+	// find the mpeg1video encoder
+	codec := ffmpeg.AvCodecFindEncoderByName(codecName)
+	if codec == nil {
+		fmt.Fprintf(os.Stderr, "Codec '%s' not found\n", codecName)
+		os.Exit(1)
+	}
+
+	avctx := ffmpeg.AvCodecAllocContext3(codec)
+	if avctx == nil {
+		fmt.Fprintf(os.Stderr, "Could not allocate video codec context\n")
+		os.Exit(1)
+	}
+
+	pkt := ffmpeg.AvPacketAlloc()
+	if pkt == nil {
+		os.Exit(1)
+	}
+
+	// put sample parameters
+	avctx.SetBitRate(400000)
+	// resolution must be a multiple of two
+	avctx.SetWidth(352)
+	avctx.SetHeight(288)
+	// frames per second
+	avctx.SetTimeBase(ffmpeg.AvMakeQ(1, 25))
+	avctx.SetFramerate(ffmpeg.AvMakeQ(25, 1))
+
+	// emit one intra frame every ten frames check frame pict_type before passing frame
+	// to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
+	// then gop_size is ignored and the output of encoder
+	// will always be I frame irrespective to gop_size
+	avctx.SetGopSize(10)
+	avctx.SetMaxBFrames(1)
+	avctx.SetPixFmt(ffmpeg.AV_PIX_FMT_YUV420P)
+
+	if codec.GetID() == ffmpeg.AV_CODEC_ID_H264 {
+		ffmpeg.AvOptSet(avctx.GetPrivData(), "preset", "slow", 0)
+	}
+
+	// open it
+	ret := ffmpeg.AvCodecOpen2(avctx, codec, nil)
+	if ret < 0 {
+		fmt.Fprintf(os.Stderr, "Could not open codec %s\n", ffmpeg.AvErr2str(ret))
+		os.Exit(1)
+	}
+
+	f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Could not open %s\n", filename)
+		os.Exit(1)
+	}
+
+	frame := ffmpeg.AvFrameAlloc()
+	if frame == nil {
+		fmt.Fprintf(os.Stderr, "Could not allocate video frame\n")
+		os.Exit(1)
+	}
+	frame.SetFormat(int32(avctx.GetPixFmt()))
+	frame.SetWidth(avctx.GetWidth())
+	frame.SetHeight(avctx.GetHeight())
+
+	ret = ffmpeg.AvFrameGetBuffer(frame, 0)
+	if ret < 0 {
+		fmt.Fprintf(os.Stderr, "Could not allocate the video frame data\n")
+		os.Exit(1)
+	}
+
+	// encode 1 second of video
+	for i := 0; i < 25; i++ {
+		// make sure the frame data is writable
+		ret = ffmpeg.AvFrameMakeWritable(frame)
+		if ret < 0 {
+			os.Exit(1)
+		}
+
+		// prepare a dummy image
+		data0 := unsafe.Slice(frame.GetDataIdx(0), avctx.GetHeight()*frame.GetLinesizeIdx(0)+avctx.GetWidth())
+		data1 := unsafe.Slice(frame.GetDataIdx(1), (avctx.GetHeight()/2)*frame.GetLinesizeIdx(1)+(avctx.GetWidth()/2))
+		data2 := unsafe.Slice(frame.GetDataIdx(2), (avctx.GetHeight()/2)*frame.GetLinesizeIdx(2)+(avctx.GetWidth()/2))
+		// Y
+		for y := 0; y < int(avctx.GetHeight()); y++ {
+			for x := 0; x < int(avctx.GetWidth()); x++ {
+				data0[y*int(frame.GetLinesizeIdx(0))+x] = uint8(x + y + i*3)
+			}
+		}
+		// Cb and Cr
+		for y := 0; y < int(avctx.GetHeight()/2); y++ {
+			for x := 0; x < int(avctx.GetWidth()/2); x++ {
+				data1[y*int(frame.GetLinesizeIdx(1))+x] = uint8(128 + y + i*2)
+				data2[y*int(frame.GetLinesizeIdx(2))+x] = uint8(64 + x + i*5)
+			}
+		}
+
+		frame.SetPts(int64(i))
+
+		// encode the image
+		encode(avctx, frame, pkt, f)
+	}
+
+	// flush the encoder
+	encode(avctx, nil, pkt, f)
+
+	// add sequence end code to have a real MPEG file
+	if codec.GetID() == ffmpeg.AV_CODEC_ID_MPEG1VIDEO || codec.GetID() == ffmpeg.AV_CODEC_ID_MPEG2VIDEO {
+		f.Write(endcode)
+	}
+	f.Close()
+
+	ffmpeg.AvCodecFreeContext(&avctx)
+	ffmpeg.AvFrameFree(&frame)
+	ffmpeg.AvPacketFree(&pkt)
+}