The practice of using Golang and FFmpeg to achieve video de-flickering

The practice of using Golang and FFmpeg to achieve video de-flickering

Overview:
The flicker problem of video is a challenge often encountered in the video processing process. When the frame rate of the recorded video does not match the lighting frequency, it may cause flickering in the video. This article will introduce how to use Golang and FFmpeg libraries to achieve video de-flickering, and provide specific code examples.

Steps:

1. Install the FFmpeg library:
   First, we need to install the FFmpeg library in the Golang development environment. It can be installed through the following command:
   go get github.com/giorgisio/goav/avcodec

       github.com/giorgisio/goav/avfilter 
       github.com/giorgisio/goav/avutil 
       github.com/giorgisio/goav/swscale
   

2. Open the video file:
   Use avformat.OpenInput( in the FFmpeg library ) function opens the video file that needs to be processed. Obtain the relevant information of the video file by passing the video file path as a parameter.

   The sample code is as follows:

   package main
   
   import (
       "fmt"
       "github.com/giorgisio/goav/avformat"
   )
   
   func main() {
       filepath := "path_to_video_file.mp4"
   
       avformat.AvRegisterAll()
   
       // 打开视频文件
       ctx := avformat.AvformatAllocContext()
       if err := avformat.AvformatOpenInput(&ctx, filepath, nil, nil); err != 0 {
           fmt.Printf("无法打开文件 %s: %s
   ", filepath, avutil.AvStrerror(err))
       }
       defer avformat.AvformatCloseInput(&ctx)
       
       // 获取视频文件信息
       if err := avformat.AvformatFindStreamInfo(ctx, nil); err < 0 {
           fmt.Printf("无法获取文件信息: %s
   ", avutil.AvStrerror(err))
       }
   }

3. Processing video frames:
   Use the avcodec.AvcodecDecodeVideo2() function in the FFmpeg library to decode video frames. Process each frame by looping through the video frames. During the processing, you can use Golang's image processing library (such as GoCV) to perform image processing operations, such as reducing brightness, increasing contrast, etc.

   The sample code is as follows:

   package main
   
   import (
       "fmt"
       "github.com/giorgisio/goav/avcodec"
       "github.com/giorgisio/goav/avformat"
       "github.com/giorgisio/goav/avutil"
       "github.com/giorgisio/goav/swscale"
       "gocv.io/x/gocv"
   )
   
   func main() {
       filepath := "path_to_video_file.mp4"
   
       avformat.AvRegisterAll()
   
       // 打开视频文件
       ctx := avformat.AvformatAllocContext()
       if err := avformat.AvformatOpenInput(&ctx, filepath, nil, nil); err != 0 {
           fmt.Printf("无法打开文件 %s: %s
   ", filepath, avutil.AvStrerror(err))
       }
       defer avformat.AvformatCloseInput(&ctx)
   
       // 获取视频文件信息
       if err := avformat.AvformatFindStreamInfo(ctx, nil); err < 0 {
           fmt.Printf("无法获取文件信息: %s
   ", avutil.AvStrerror(err))
       }
   
       // 查找视频流索引
       streamIndex := avutil.AvFindBestStream(ctx, avutil.AvmediaType(avformat.AvmTypeVideo), -1, -1, nil, 0)
   
       codecParams := ctx.Streams()[streamIndex].CodecParameters()
   
       // 获取解码器
       codec := avcodec.AvcodecFindDecoder(codecParams.CodecId())
       if codec == nil {
           fmt.Println("无法获取解码器")
       }
   
       // 打开解码器
       codecCtx := avcodec.AvcodecAllocContext3(codec)
       if err := avcodec.AvcodecParametersToContext(codecCtx, codecParams); err < 0 {
           fmt.Printf("无法打开解码器: %s
   ", avutil.AvStrerror(err))
       }
       defer avcodec.AvcodecFreeContext(&codecCtx)
   
       if err := avcodec.AvcodecOpen2(codecCtx, codec, nil); err < 0 {
           fmt.Printf("无法打开解码器: %s
   ", avutil.AvStrerror(err))
       }
   
       // 初始化帧
       frame := avutil.AvFrameAlloc()
       defer avutil.AvFrameFree(&frame)
   
       // 初始化解码器上下文
       packet := avcodec.AvPacketAlloc()
       defer avcodec.AvPacketFree(&packet)
   
       swsCtx := swscale.SwsGetContext(codecParams.Width(), codecParams.Height(), codecCtx.PixFmt(),
           codecParams.Width(), codecParams.Height(), avutil.AV_PIX_FMT_BGR24,
           swscale.SWS_BICUBIC, nil, nil, nil)
       defer swscale.SwsFreeContext(&swsCtx)
   
       for {
           // 读取帧
           if err := avformat.AvReadFrame(ctx, packet); err != 0 {
               fmt.Printf("无法读取帧: %s
   ", avutil.AvStrerror(err))
               break
           }
   
           if packet.StreamIndex() == streamIndex {
               if err := avcodec.AvcodecSendPacket(codecCtx, packet); err < 0 {
                   fmt.Printf("无法发送数据包到解码器: %s
   ", avutil.AvStrerror(err))
               }
   
               if err := avcodec.AvcodecReceiveFrame(codecCtx, frame); err < 0 {
                   fmt.Printf("无法接收解码帧: %s
   ", avutil.AvStrerror(err))
               }
   
               // 进行图像处理操作
               img := gocv.NewMatFromBytes(codecParams.Width(), codecParams.Height(), gocv.MatType(gocv.MatTypeCV8UC3), frame.Data(0))
               imgDst := gocv.NewMat()
   
               // 图像处理操作，以减少亮度为例
               gocv.ConvertScaleAbs(img, &imgDst, 0.5, 0)
   
               // 输出图像
               fmt.Printf("输出图像: %v
   ", imgDst)
   
               img.Close()
               imgDst.Close()
           }
   
           avcodec.AvPacketUnref(packet)
       }
   }

4. Write the processed video:
   Use the avcodec.AvcodecEncodeVideo2() function in the FFmpeg library to encode the processed video frame , and then use the avformat.AvWriteFrame() function to write the encoded frame to the target video file.

   The sample code is as follows:

   package main
   
   import (
       "fmt"
       "github.com/giorgisio/goav/avcodec"
       "github.com/giorgisio/goav/avformat"
       "github.com/giorgisio/goav/avutil"
       "github.com/giorgisio/goav/swscale"
       "gocv.io/x/gocv"
   )
   
   func main() {
       filepath := "path_to_video_file.mp4"
       outputpath := "path_to_output_file.mp4"
   
       avformat.AvRegisterAll()
   
       // 打开视频文件
       ctx := avformat.AvformatAllocContext()
       if err := avformat.AvformatOpenInput(&ctx, filepath, nil, nil); err != 0 {
           fmt.Printf("无法打开文件 %s: %s
   ", filepath, avutil.AvStrerror(err))
       }
       defer avformat.AvformatCloseInput(&ctx)
   
       // 获取视频文件信息
       if err := avformat.AvformatFindStreamInfo(ctx, nil); err < 0 {
           fmt.Printf("无法获取文件信息: %s
   ", avutil.AvStrerror(err))
       }
   
       // 查找视频流索引
       streamIndex := avutil.AvFindBestStream(ctx, avutil.AvmediaType(avformat.AvmTypeVideo), -1, -1, nil, 0)
   
       codecParams := ctx.Streams()[streamIndex].CodecParameters()
   
       // 获取解码器
       codec := avcodec.AvcodecFindDecoder(codecParams.CodecId())
       if codec == nil {
           fmt.Println("无法获取解码器")
       }
   
       // 打开解码器
       codecCtx := avcodec.AvcodecAllocContext3(codec)
       if err := avcodec.AvcodecParametersToContext(codecCtx, codecParams); err < 0 {
           fmt.Printf("无法打开解码器: %s
   ", avutil.AvStrerror(err))
       }
       defer avcodec.AvcodecFreeContext(&codecCtx)
   
       if err := avcodec.AvcodecOpen2(codecCtx, codec, nil); err < 0 {
           fmt.Printf("无法打开解码器: %s
   ", avutil.AvStrerror(err))
       }
   
       // 初始化帧
       frame := avutil.AvFrameAlloc()
       defer avutil.AvFrameFree(&frame)
   
       // 初始化解码器上下文
       packet := avcodec.AvPacketAlloc()
       defer avcodec.AvPacketFree(&packet)
   
       swsCtx := swscale.SwsGetContext(codecParams.Width(), codecParams.Height(), codecCtx.PixFmt(),
           codecParams.Width(), codecParams.Height(), avutil.AV_PIX_FMT_BGR24,
           swscale.SWS_BICUBIC, nil, nil, nil)
       defer swscale.SwsFreeContext(&swsCtx)
   
       // 创建输出格式上下文
       fmtCtx := avformat.AvformatAllocContext()
       defer avformat.AvformatFreeContext(fmtCtx)
   
       // 设置输出文件的格式
       fmtCtx.SetOutputFormat(avformat.AvGuessFormat("", outputpath, ""))
   
       // 创建输出文件
       if avformat.AvioOpen(&fmtCtx.Pb, outputpath, avformat.AVIO_FLAG_WRITE) < 0 {
           fmt.Println("无法打开输出文件")
       }
   
       // 写入文件头部
       if avformat.AvformatWriteHeader(fmtCtx, nil) < 0 {
           fmt.Println("无法写入文件头部")
       }
   
       for {
           // 读取帧
           if err := avformat.AvReadFrame(ctx, packet); err != 0 {
               fmt.Printf("无法读取帧: %s
   ", avutil.AvStrerror(err))
               break
           }
   
           if packet.StreamIndex() == streamIndex {
               if err := avcodec.AvcodecSendPacket(codecCtx, packet); err < 0 {
                   fmt.Printf("无法发送数据包到解码器: %s
   ", avutil.AvStrerror(err))
               }
   
               if err := avcodec.AvcodecReceiveFrame(codecCtx, frame); err < 0 {
                   fmt.Printf("无法接收解码帧: %s
   ", avutil.AvStrerror(err))
               }
   
               // 进行图像处理操作
               img := gocv.NewMatFromBytes(codecParams.Width(), codecParams.Height(), gocv.MatType(gocv.MatTypeCV8UC3), frame.Data(0))
               imgDst := gocv.NewMat()
   
               // 图像处理操作，以减少亮度为例
               gocv.ConvertScaleAbs(img, &imgDst, 0.5, 0)
   
               // 将处理后的图像数据转换为原始数据
               dstData := imgDst.ToBytes()
   
               // 创建输出帧
               outputFrame := avutil.AvFrameAlloc()
               defer avutil.AvFrameFree(&outputFrame)
   
               outputFrame.SetData(dstData)
   
               // 编码输出帧
               if err := avcodec.AvcodecSendFrame(codecCtx, outputFrame); err < 0 {
                   fmt.Printf("无法发送输出帧到编码器: %s
   ", avutil.AvStrerror(err))
               }
   
               for err := avcodec.AvcodecReceivePacket(codecCtx, packet); err >= 0; err = avcodec.AvcodecReceivePacket(codecCtx, packet) {
                   packet.SetStreamIndex(0)
                   packet.RescaleTs(codecCtx.TimeBase(), ctx.Streams()[streamIndex].TimeBase())
   
                   if err := avformat.AvWriteFrame(fmtCtx, packet); err < 0 {
                       fmt.Printf("无法写入帧: %s
   ", avutil.AvStrerror(err))
                   }
                   avcodec.AvPacketUnref(packet)
               }
   
               img.Close()
               imgDst.Close()
           }
   
           avcodec.AvPacketUnref(packet)
       }
   
       // 写入文件尾部
       avformat.AvWriteTrailer(fmtCtx)
   }

Summary:
This article introduces how to use Golang and FFmpeg libraries to achieve video de-flickering, and provides detailed Code examples. By using the functions in the FFmpeg library, we can open the video file, process the video frames, and re-encode the processed frames and write them to the target video file. In practice, image processing operations can be performed according to specific needs to solve the video flicker problem. Leveraging the power of Golang and FFmpeg, we can handle video flickering problems more flexibly and efficiently.

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