Go语言调用FFmpeg解码MP4并转换为YUV420SP格式

在多媒体处理领域，FFmpeg是一款非常强大的开源工具，它可以处理包括视频编码、解码、转码、流处理等在内的多种任务。在Go语言中，我们可以利用exec包来调用FFmpeg的命令行接口，从而实现MP4文件的解码和格式转换。

首先，确保你的系统上已经安装了FFmpeg，并且它的可执行文件路径已经添加到环境变量中，这样Go程序就可以调用它了。

接下来，我们将通过以下步骤来实现MP4到YUV420SP的转换：

1. 使用FFmpeg解码MP4文件，并将解码后的帧输出为原始YUV420P格式。

2. 读取YUV420P格式的数据，并将其转换为YUV420SP格式。

3. 将转换后的YUV420SP数据写入文件保存。

下面是Go语言实现上述步骤的示例代码：

```go
package main

import (
“fmt”
“os”
“os/exec”
“log”
“io/ioutil”
“encoding/binary”
)

// YUV420P to YUV420SP conversion function
func ConvertYUV420PtoYUV420SP(inputFile, outputFile string) error {
// Read YUV420P data from the input file
yuv420pData, err := ioutil.ReadFile(inputFile)
if err != nil {
return err
}

// Get the dimensions of the video frame
// Assuming the input file has a single frame for simplicity
cmd := exec.Command("ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries", "stream=width,height", "-of", "default=noprint_wrappers=1:nokey=1", inputFile)
output, err := cmd.Output()
if err != nil {
    return err
}
widthStr, heightStr := string(output).Split("=")
width, err := strconv.Atoi(widthStr[len(widthStr)-4:])
if err != nil {
    return err
}
height, err := strconv.Atoi(heightStr[len(heightStr)-5:])
if err != nil {
    return err
}
// YUV420P frame size calculation
frameSize := width * height
uvSize := frameSize / 4
// Initialize output YUV420SP buffer
yuv420SPData := make([]byte, frameSize+uvSize)
// Populate the Y plane
copy(yuv420SPData[:frameSize], yuv420pData[:frameSize])
// Convert UV planes from interleaved (YUV420P) to planar (YUV420SP)
for i := 0; i < uvSize; i++ {
    // V plane (U in YUV420SP)
    yuv420SPData[frameSize+i] = yuv420pData[frameSize+2*i]
    // U plane (V in YUV420SP)
    yuv420SPData[frameSize+uvSize+i] = yuv420pData[frameSize+2*i+1]
}
// Write the converted YUV420SP data to the output file
err = ioutil.WriteFile(outputFile, yuv420SPData, 0644)
if err != nil {
    return err
}
return nil

}

func main() {
// FFmpeg command to decode MP4 to YUV420P
decodeCmd := exec.Command(“ffmpeg”, “-i”, “input.mp4”, “-vf”, “format=yuv420p”, “-“)

// Create a pipe to read the decoded frame data
r, w, err := os.Pipe()
if err != nil {
    log.Fatal(err)
}