2023-03-24：音视频mp3和h264混合（muxer）编码为mp4，用go语言编写。

2023-03-24：音视频mp3和h264混合（muxer）编码为mp4，用go语言编写。

答案2023-03-24：

这是一个使用FFmpeg库将MP3和H.264混合编码为MP4的Go语言程序。程序的大体过程如下：

1.设置FFmpeg库路径和环境变量。

2.检查并创建输出目录，以及输入视频和音频文件。

3.打开输入视频文件并查找视频流，打开输入音频文件并查找音频流。

4.新建输出上下文，并为视频和音频创建新的输出流。

5.打开输出文件。

6.写输出文件头。

7.读取输入视频和音频帧，将它们转换为输出格式，写入输出文件。在这个过程中，需要进行PTS/DTS转换和比特流过滤（如果需要）。

8.写输出文件尾。

9.清理资源并关闭输入和输出文件。

10.播放输出文件（可选）。

代码见github/moonfdd/ffmpeg-go库。

执行命令：

go run ./examples/a24.video_muxer_mp3h2642mp4/main.go

代码参考24：音视频mp3和h264混合（muxer）编码为mp4，代码如下：

// https://feater.top/ffmpeg/ffmpeg-muxer-encode-mp3-h264-to-mp4
package main

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

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

/*
FIX: H.264 in some container format (FLV, MP4, MKV etc.) need
"h264_mp4toannexb" bitstream filter (BSF)
  *Add SPS,PPS in front of IDR frame
  *Add start code ("0,0,0,1") in front of NALU
H.264 in some container (MPEG2TS) don't need this BSF.
*/
//'1': Use H.264 Bitstream Filter
const USE_H264BSF = 0

/*
FIX:AAC in some container format (FLV, MP4, MKV etc.) need
"aac_adtstoasc" bitstream filter (BSF)
*/
//'1': Use AAC Bitstream Filter
const USE_AACBSF = 0

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-58.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
        }
    }

    inFilenameVideo := "./out/a24.h264"
    inFilenameAudio := "./out/a24.aac"
    outFilename := "./out/a24.mp4"

    _, err = os.Stat(inFilenameVideo)
    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", inFilenameVideo).Output()
        }
    }

    _, err = os.Stat(inFilenameAudio)
    if err != nil {
        if os.IsNotExist(err) {
            fmt.Println("create aac file")
            exec.Command("./lib/ffmpeg", "-i", "./resources/big_buck_bunny.mp4", "-acodec", "copy", "-vn", inFilenameAudio).Output()
        }
    }

    var ifmtCtxVideo, ifmtCtxAudio, ofmtCtx *libavformat.AVFormatContext
    var packet libavcodec.AVPacket

    var inVideoIndex, inAudioIndex ffcommon.FInt = -1, -1
    var outVideoIndex, outAudioIndex ffcommon.FInt = -1, -1
    var frameIndex ffcommon.FInt = 0

    var curPstVideo, curPstAudio ffcommon.FInt64T = 0, 0

    var ret ffcommon.FInt = 0
    var i ffcommon.FUnsignedInt = 0

    var h264bsfc, aacbsfc *libavcodec.AVBitStreamFilterContext

    //打开输入视频文件
    ret = libavformat.AvformatOpenInput(&ifmtCtxVideo, inFilenameVideo, nil, nil)
    if ret < 0 {
        fmt.Printf("can't open input video file\n")
        goto end
    }

    //查找输入流
    ret = ifmtCtxVideo.AvformatFindStreamInfo(nil)
    if ret < 0 {
        fmt.Printf("failed to retrieve input video stream information\n")
        goto end
    }

    //打开输入音频文件
    ret = libavformat.AvformatOpenInput(&ifmtCtxAudio, inFilenameAudio, nil, nil)
    if ret < 0 {
        fmt.Printf("can't open input audio file\n")
        goto end
    }

    //查找输入流
    ret = ifmtCtxAudio.AvformatFindStreamInfo(nil)
    if ret < 0 {
        fmt.Printf("failed to retrieve input audio stream information\n")
        goto end
    }

    fmt.Printf("===========Input Information==========\n")
    ifmtCtxVideo.AvDumpFormat(0, inFilenameVideo, 0)
    ifmtCtxAudio.AvDumpFormat(0, inFilenameAudio, 0)
    fmt.Printf("======================================\n")

    //新建输出上下文
    libavformat.AvformatAllocOutputContext2(&ofmtCtx, nil, "", outFilename)
    if ofmtCtx == nil {
        fmt.Printf("can't create output context\n")
        goto end
    }

    //视频输入流
    for i = 0; i < ifmtCtxVideo.NbStreams; i++ {
        if ifmtCtxVideo.GetStream(i).Codecpar.CodecType == libavutil.AVMEDIA_TYPE_VIDEO {
            inStream := ifmtCtxVideo.GetStream(i)
            outStream := ofmtCtx.AvformatNewStream(nil)
            inVideoIndex = int32(i)

            if outStream == nil {
                fmt.Printf("failed to allocate output stream\n")
                goto end
            }

            outVideoIndex = outStream.Index

            if libavcodec.AvcodecParametersCopy(outStream.Codecpar, inStream.Codecpar) < 0 {
                fmt.Printf("faild to copy context from input to output stream")
                goto end
            }

            outStream.Codecpar.CodecTag = 0

            break
        }
    }

    //音频输入流
    for i = 0; i < ifmtCtxAudio.NbStreams; i++ {
        if ifmtCtxAudio.GetStream(i).Codecpar.CodecType == libavutil.AVMEDIA_TYPE_AUDIO {
            inStream := ifmtCtxAudio.GetStream(i)
            outStream := ofmtCtx.AvformatNewStream(nil)
            inAudioIndex = int32(i)

            if outStream == nil {
                fmt.Printf("failed to allocate output stream\n")
                goto end
            }

            outAudioIndex = outStream.Index

            if libavcodec.AvcodecParametersCopy(outStream.Codecpar, inStream.Codecpar) < 0 {
                fmt.Printf("faild to copy context from input to output stream")
                goto end
            }

            outStream.Codecpar.CodecTag = 0

            break
        }
    }

    fmt.Printf("==========Output Information==========\n")
    ofmtCtx.AvDumpFormat(0, outFilename, 1)
    fmt.Printf("======================================\n")

    //打开输入文件
    if ofmtCtx.Oformat.Flags&libavformat.AVFMT_NOFILE == 0 {
        if libavformat.AvioOpen(&ofmtCtx.Pb, outFilename, libavformat.AVIO_FLAG_WRITE) < 0 {
            fmt.Printf("can't open out file\n")
            goto end
        }
    }

    //写文件头
    if ofmtCtx.AvformatWriteHeader(nil) < 0 {
        fmt.Printf("Error occurred when opening output file\n")
        goto end
    }

    if USE_H264BSF != 0 {
        h264bsfc = libavcodec.AvBitstreamFilterInit("h264_mp4toannexb")
    }
    if USE_AACBSF != 0 {
        aacbsfc = libavcodec.AvBitstreamFilterInit("aac_adtstoasc")
    }
    for {
        var ifmtCtx *libavformat.AVFormatContext
        var inStream, outStream *libavformat.AVStream
        var streamIndex ffcommon.FInt = 0

        if libavutil.AvCompareTs(curPstVideo, ifmtCtxVideo.GetStream(uint32(inVideoIndex)).TimeBase, curPstAudio, ifmtCtxAudio.GetStream(uint32(inAudioIndex)).TimeBase) < 0 {
            ifmtCtx = ifmtCtxVideo
            streamIndex = outVideoIndex

            if ifmtCtx.AvReadFrame(&packet) >= 0 {
                for {
                    inStream = ifmtCtx.GetStream(packet.StreamIndex)
                    outStream = ofmtCtx.GetStream(uint32(streamIndex))

                    if packet.StreamIndex == uint32(inVideoIndex) {
                        //Fix: No PTS(Example: Raw H.264
                        //Simple Write PTS
                        if packet.Pts == libavutil.AV_NOPTS_VALUE {
                            //write PTS
                            timeBase1 := inStream.TimeBase
                            //Duration between 2 frames
                            calcDuration := int64(libavutil.AV_TIME_BASE / libavutil.AvQ2d(inStream.RFrameRate))
                            //Parameters
                            packet.Pts = int64((float64(frameIndex) * float64(calcDuration)) / (libavutil.AvQ2d(timeBase1) * libavutil.AV_TIME_BASE))
                            packet.Dts = packet.Pts
                            packet.Duration = int64(float64(calcDuration) / (libavutil.AvQ2d(timeBase1) * libavutil.AV_TIME_BASE))
                            frameIndex++
                        }

                        curPstVideo = packet.Pts
                        break
                    }
                    if ifmtCtx.AvReadFrame(&packet) >= 0 {

                    } else {
                        break
                    }
                }
            } else {
                break
            }
        } else {
            ifmtCtx = ifmtCtxAudio
            streamIndex = outAudioIndex

            if ifmtCtx.AvReadFrame(&packet) >= 0 {
                for {
                    inStream = ifmtCtx.GetStream(packet.StreamIndex)
                    outStream = ofmtCtx.GetStream(uint32(streamIndex))

                    if packet.StreamIndex == uint32(inAudioIndex) {
                        //Fix: No PTS(Example: Raw H.264
                        //Simple Write PTS
                        if packet.Pts == libavutil.AV_NOPTS_VALUE {
                            //write PTS
                            timeBase1 := inStream.TimeBase
                            //Duration between 2 frames
                            calcDuration := int64(libavutil.AV_TIME_BASE / libavutil.AvQ2d(inStream.RFrameRate))
                            //Parameters
                            packet.Pts = int64((float64(frameIndex) * float64(calcDuration)) / (libavutil.AvQ2d(timeBase1) * libavutil.AV_TIME_BASE))
                            packet.Dts = packet.Pts
                            packet.Duration = int64(float64(calcDuration) / (libavutil.AvQ2d(timeBase1) * libavutil.AV_TIME_BASE))
                            frameIndex++
                        }

                        curPstAudio = packet.Pts
                        break
                    }
                    if ifmtCtx.AvReadFrame(&packet) >= 0 {

                    } else {
                        break
                    }
                }
            } else {
                break
            }
        }

        //FIX:Bitstream Filter
        if USE_H264BSF != 0 {
            h264bsfc.AvBitstreamFilterFilter(inStream.Codec, "", &packet.Data, (*int32)(unsafe.Pointer(&packet.Size)), packet.Data, int32(packet.Size), 0)
        }
        if USE_AACBSF != 0 {
            aacbsfc.AvBitstreamFilterFilter(outStream.Codec, "", &packet.Data, (*int32)(unsafe.Pointer(&packet.Size)), packet.Data, int32(packet.Size), 0)
        }

        //Convert PTS/DTS
        packet.Pts = libavutil.AvRescaleQRnd(packet.Pts, inStream.TimeBase, outStream.TimeBase, libavutil.AV_ROUND_NEAR_INF|libavutil.AV_ROUND_PASS_MINMAX)
        packet.Dts = libavutil.AvRescaleQRnd(packet.Dts, inStream.TimeBase, outStream.TimeBase, libavutil.AV_ROUND_NEAR_INF|libavutil.AV_ROUND_PASS_MINMAX)
        packet.Duration = libavutil.AvRescaleQ(packet.Duration, inStream.TimeBase, outStream.TimeBase)
        packet.Pos = -1
        packet.StreamIndex = uint32(streamIndex)

        //write
        if ofmtCtx.AvInterleavedWriteFrame(&packet) < 0 {
            fmt.Printf("error muxing packet")
            break
        }

        packet.AvPacketUnref()
    }

    //Write file trailer
    ofmtCtx.AvWriteTrailer()

    if USE_H264BSF != 0 {
        h264bsfc.AvBitstreamFilterClose()
    }
    if USE_AACBSF != 0 {
        aacbsfc.AvBitstreamFilterClose()
    }

end:
    libavformat.AvformatCloseInput(&ifmtCtxVideo)
    libavformat.AvformatCloseInput(&ifmtCtxAudio)
    if ofmtCtx != nil && ofmtCtx.Oformat.Flags&libavformat.AVFMT_NOFILE == 0 {
        ofmtCtx.Pb.AvioClose()
    }

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

本作品采用《CC 协议》，转载必须注明作者和本文链接