2023-03-01:用moonfdd/ffmpeg-go库，将h264文件编码为mp4文件。

2023-03-01：用moonfdd/ffmpeg-go库，将h264文件编码为mp4文件。

答案2023-03-01：

使用 github.com/moonfdd/ffmpeg-go 库。现在我们有h264的流，创建一个mp4文件，新建一条流并将h264流插入进去。（暂时没有音频部分）。

转换流程图为：

命令如下：

go run ./examples/a13.video_encode_h2642mp4/main.go

参考了[13：h264编码为mp4](https://feater.top/ffmpeg/ffmpeg-encode-h264-to-mp4)，代码用golang编写。代码如下：

package main


import (
  "fmt"
  "os"
  "os/exec"


  "github.com/moonfdd/ffmpeg-go/ffcommon"
  "github.com/moonfdd/ffmpeg-go/libavcodec"
  "github.com/moonfdd/ffmpeg-go/libavformat"
  "github.com/moonfdd/ffmpeg-go/libavutil"
)


func main() {
  os.Setenv("Path", os.Getenv("Path")+";./lib")
  ffcommon.SetAvutilPath("./lib/avutil-56.dll")
  ffcommon.SetAvcodecPath("./lib/avcodec-58.dll")
  ffcommon.SetAvdevicePath("./lib/avdevice-56.dll")
  ffcommon.SetAvfilterPath("./lib/avfilter-56.dll")
  ffcommon.SetAvformatPath("./lib/avformat-58.dll")
  ffcommon.SetAvpostprocPath("./lib/postproc-55.dll")
  ffcommon.SetAvswresamplePath("./lib/swresample-3.dll")
  ffcommon.SetAvswscalePath("./lib/swscale-5.dll")


  genDir := "./out"
  _, err := os.Stat(genDir)
  if err != nil {
    if os.IsNotExist(err) {
      os.Mkdir(genDir, 0777) //  Everyone can read write and execute
    }
  }


  frame_index := 0 //统计帧数
  inVStreamIndex := -1
  outVStreamIndex := -1 //输入输出视频流在文件中的索引位置
  inVFileName := "./out/result.h264"
  outFileName := "./out/result.mp4"


  //是否存在h264文件
  _, err = os.Stat(inVFileName)
  if err != nil {
    if os.IsNotExist(err) {
      fmt.Println("create h264 file")
      exec.Command("./lib/ffmpeg", "-i", "./resources/big_buck_bunny.mp4", "-vcodec", "copy", "-an", inVFileName, "-y").CombinedOutput()
    }
  }


  var inVFmtCtx *libavformat.AVFormatContext
  var outFmtCtx *libavformat.AVFormatContext
  var codecPara *libavcodec.AVCodecParameters
  var outVStream *libavformat.AVStream
  var outCodec *libavcodec.AVCodec
  var outCodecCtx *libavcodec.AVCodecContext
  var outCodecPara *libavcodec.AVCodecParameters
  var inVStream *libavformat.AVStream
  pkt := libavcodec.AvPacketAlloc()


  for {
    //======================输入部分============================//
    //打开输入文件
    if libavformat.AvformatOpenInput(&inVFmtCtx, inVFileName, nil, nil) < 0 {
      fmt.Printf("Cannot open input file.\n")
      break
    }


    //查找输入文件中的流
    if inVFmtCtx.AvformatFindStreamInfo(nil) < 0 {
      fmt.Printf("Cannot find stream info in input file.\n")
      break
    }


    //查找视频流在文件中的位置
    for i := uint32(0); i < inVFmtCtx.NbStreams; i++ {
      if inVFmtCtx.GetStream(i).Codecpar.CodecType == libavutil.AVMEDIA_TYPE_VIDEO {
        inVStreamIndex = int(i)
        break
      }
    }


    codecPara = inVFmtCtx.GetStream(uint32(inVStreamIndex)).Codecpar //输入视频流的编码参数


    fmt.Printf("===============Input information========>\n")
    inVFmtCtx.AvDumpFormat(0, inVFileName, 0)
    fmt.Printf("===============Input information========<\n")


    //=====================输出部分=========================//
    //打开输出文件并填充格式数据
    if libavformat.AvformatAllocOutputContext2(&outFmtCtx, nil, "", outFileName) < 0 {
      fmt.Printf("Cannot alloc output file context.\n")
      break
    }


    //打开输出文件并填充数据
    if libavformat.AvioOpen(&outFmtCtx.Pb, outFileName, libavformat.AVIO_FLAG_READ_WRITE) < 0 {
      fmt.Printf("output file open failed.\n")
      break
    }


    //在输出的mp4文件中创建一条视频流
    outVStream = outFmtCtx.AvformatNewStream(nil)
    if outVStream == nil {
      fmt.Printf("Failed allocating output stream.\n")
      break
    }
    outVStream.TimeBase.Den = 25
    outVStream.TimeBase.Num = 1
    outVStreamIndex = int(outVStream.Index)


    //查找编码器
    outCodec = libavcodec.AvcodecFindEncoder(codecPara.CodecId)
    if outCodec == nil {
      fmt.Printf("Cannot find any encoder.\n")
      break
    }


    //从输入的h264编码器数据复制一份到输出文件的编码器中
    outCodecCtx = outCodec.AvcodecAllocContext3()
    outCodecPara = outFmtCtx.GetStream(uint32(outVStream.Index)).Codecpar
    if libavcodec.AvcodecParametersCopy(outCodecPara, codecPara) < 0 {
      fmt.Printf("Cannot copy codec para.\n")
      break
    }
    if outCodecCtx.AvcodecParametersToContext(outCodecPara) < 0 {
      fmt.Printf("Cannot alloc codec ctx from para.\n")
      break
    }
    outCodecCtx.TimeBase.Den = 25
    outCodecCtx.TimeBase.Num = 1


    //打开输出文件需要的编码器
    if outCodecCtx.AvcodecOpen2(outCodec, nil) < 0 {
      fmt.Printf("Cannot open output codec.\n")
      break
    }


    fmt.Printf("============Output Information=============>\n")
    outFmtCtx.AvDumpFormat(0, outFileName, 1)
    fmt.Printf("============Output Information=============<\n")


    //写入文件头
    if outFmtCtx.AvformatWriteHeader(nil) < 0 {
      fmt.Printf("Cannot write header to file.\n")
      return
    }
    //===============编码部分===============//


    inVStream = inVFmtCtx.GetStream(uint32(inVStreamIndex))
    for inVFmtCtx.AvReadFrame(pkt) >= 0 { //循环读取每一帧直到读完
      if pkt.StreamIndex == uint32(inVStreamIndex) { //确保处理的是视频流
        //FIXME：No PTS (Example: Raw H.264)
        //Simple Write PTS
        //如果当前处理帧的显示时间戳为0或者没有等等不是正常值
        if pkt.Pts == libavutil.AV_NOPTS_VALUE {
          fmt.Printf("frame_index:%d\n", frame_index)
          //Write PTS
          time_base1 := inVStream.TimeBase
          //Duration between 2 frames (us)
          calc_duration := libavutil.AV_TIME_BASE / libavutil.AvQ2d(inVStream.RFrameRate)


          //Parameters
          pkt.Pts = int64((float64(frame_index) * calc_duration) / (libavutil.AvQ2d(time_base1) * float64(libavutil.AV_TIME_BASE)))
          pkt.Dts = pkt.Pts
          pkt.Duration = int64(calc_duration / (libavutil.AvQ2d(time_base1) * float64(libavutil.AV_TIME_BASE)))
          frame_index++
        }
        //Convert PTS/DTS
        pkt.Pts = libavutil.AvRescaleQRnd(pkt.Pts, inVStream.TimeBase, outVStream.TimeBase, libavutil.AV_ROUND_NEAR_INF|libavutil.AV_ROUND_PASS_MINMAX)
        pkt.Dts = libavutil.AvRescaleQRnd(pkt.Dts, inVStream.TimeBase, outVStream.TimeBase, libavutil.AV_ROUND_NEAR_INF|libavutil.AV_ROUND_PASS_MINMAX)
        pkt.Duration = libavutil.AvRescaleQ(pkt.Duration, inVStream.TimeBase, outVStream.TimeBase)
        pkt.Pos = -1
        pkt.StreamIndex = uint32(outVStreamIndex)
        fmt.Printf("Write 1 Packet. size:%5d\tpts:%d\tduration:%d\n", pkt.Size, pkt.Pts, pkt.Duration)


        //Write
        if outFmtCtx.AvInterleavedWriteFrame(pkt) < 0 {
          fmt.Printf("Error muxing packet\n")
          break
        }
        pkt.AvPacketUnref()
      }
    }
    outFmtCtx.AvWriteTrailer()
    break
  }


  //===========================释放所有指针===============================//
  libavcodec.AvPacketFree(&pkt)
  libavformat.AvformatCloseInput(&outFmtCtx)
  outCodecCtx.AvcodecClose()
  libavcodec.AvcodecFreeContext(&outCodecCtx)
  libavformat.AvformatCloseInput(&inVFmtCtx)
  inVFmtCtx.AvformatFreeContext()
  // outFmtCtx.Pb.AvioClose()//案例里面有，但个人感觉不对


  fmt.Println("-----------------------------------------")
  _, err = exec.Command("./lib/ffplay.exe", "./out/result.mp4").Output()
  if err != nil {
    fmt.Println("play err = ", err)
  }
}