我有一个电子程序，可以选择一个风景视频的多个区域，让你在一个肖像画布上重新排列它们。我在建立正确的ffmpeg命令来创建视频时遇到了问题。我有这个有点工作。我可以导出2层，但如果我只有1层或如果我选择了3层或更多层，则无法导出。
选择2个视频区域

layers [
  { top: 0, left: 658, width: 576, height: 1080 },
  { top: 262, left: 0, width: 576, height: 324 }
]
newPositions [
  { top: 0, left: 0, width: 576, height: 1080 },
  { top: 0, left: 0, width: 576, height: 324 }
]
filtergraph [0]crop=576:1080:658:0,scale=576:1080[v0];[0]crop=576:324:0:262,scale=576:324[v1];[v0][v1]overlay=0:0:0:0[out]

No Error export successful

选择1个地区

layers [ { top: 0, left: 650, width: 576, height: 1080 } ]
newPositions [ { top: 0, left: 0, width: 576, height: 1080 } ]
filtergraph [0]crop=576:1080:650:0,scale=576:1080[v0];[v0]overlay=0:0[out]

FFmpeg error: [fc#0 @ 000001dd3b6db0c0] Cannot find a matching stream for unlabeled input pad overlay
Error initializing complex filters: Invalid argument

选择3个视频区域

layers [
  { top: 0, left: 641, width: 576, height: 1080 },
  { top: 250, left: 0, width: 576, height: 324 },
  { top: 756, left: 0, width: 576, height: 324 }
]
newPositions [
  { top: 0, left: 0, width: 576, height: 1080 },
  { top: 0, left: 0, width: 576, height: 324 },
  { top: 756, left: 0, width: 576, height: 324 }
]
filtergraph [0]crop=576:1080:641:0,scale=576:1080[v0];[0]crop=576:324:0:250,scale=576:324[v1];[0]crop=576:324:0:756,scale=576:324[v2];[v0][v1][v2]overlay=0:0:0:0:0:756[out]

FFmpeg error: [AVFilterGraph @ 0000018faf2189c0] More input link labels specified for filter 'overlay' than it has inputs: 3 > 2
[AVFilterGraph @ 0000018faf2189c0] Error linking filters

FFmpeg error: Failed to set value '[0]crop=576:1080:698:0,scale=576:1080[v0];[0]crop=576:324:0:264,scale=576:324[v1];[0]crop=576:324:0:756,scale=576:324[v2];[v0][v1][v2]overlay=0:0:0:0:0:0[out]' for option 'filter_complex': Invalid argument
Error parsing global options: Invalid argument

我不知道如何构造正确的叠加命令。下面是我在我的电子应用程序中使用的js代码。

ipcMain.handle('export-video', async (_event, args) => {
  const { videoFile, outputName, layers, newPositions } = args;
  const ffmpegPath = path.join(__dirname, 'bin', 'ffmpeg');
  const outputDir = checkOutputDir();
  
  // use same video for each layer as input
  // crop, scale, and position each layer
  // overlay each layer on top of each other

  // export video
  console.log('layers', layers);
  console.log('newPositions', newPositions);

  let filtergraph = '';

  for (let i = 0; i < layers.length; i++) {
    const { top, left, width, height } = layers[i];
    const { width: newWidth, height: newHeight } = newPositions[i];
    const filter = `[0]crop=${width}:${height}:${left}:${top},scale=${newWidth}:${newHeight}[v${i}];`;
    filtergraph += filter;
  }

  for (let i = 0; i < layers.length; i++) {
    const filter = `[v${i}]`;
    filtergraph += filter;
  }

  filtergraph += `overlay=`;
  for (let i = 0; i < layers.length; i++) {
    const { top: newTop, left: newLeft } = newPositions[i];
    const overlay = `${newLeft}:${newTop}:`;
    filtergraph += overlay;
  }

  filtergraph = filtergraph.slice(0, -1); // remove last comma
  filtergraph += `[out]`;
  
  console.log('filtergraph', filtergraph);

  const ffmpeg = spawn(ffmpegPath, [
    '-i', videoFile,
    '-filter_complex', filtergraph,
    '-map', '[out]',
    '-c:v', 'libx264',
    '-preset', 'ultrafast',
    '-crf', '18',
    '-y',
    path.join(outputDir, `${outputName}`)
  ]);  

  ffmpeg.stdout.on('data', (data) => {
    console.log(`FFmpeg output: ${data}`);
  });

  ffmpeg.stderr.on('data', (data) => {
    console.error(`FFmpeg error: ${data}`);
  });

  ffmpeg.on('close', (code) => {
    console.log(`FFmpeg process exited with code ${code}`);
    // event.reply('ffmpeg-export-done'); // Notify the renderer process
  });
});

任何建议都可能是有帮助的，文档很混乱，谢谢。

编辑我越来越接近这个输出：

layers [
  { top: 0, left: 677, width: 576, height: 1080 },
  { top: 240, left: 0, width: 576, height: 324 }
]
newPositions [
  { top: 0, left: 0, width: 576, height: 1080 },
  { top: 0, left: 0, width: 576, height: 324 }
]
filtergraph [0]crop=576:1080:677:0,scale=576:1080[v0];[0]crop=576:324:0:240,scale=576:324[v1];[0][v0]overlay=0:0[o0];[o0][v1]overlay=0:0[o1]

ipcMain.handle('export-video', async (_event, args) => {
  const { videoFile, outputName, layers, newPositions } = args;
  const ffmpegPath = path.join(__dirname, 'bin', 'ffmpeg');
  const outputDir = checkOutputDir();
  
  // use same video for each layer as input
  // crop, scale, and position each layer
  // overlay each layer on top of each other

  // export video
  console.log('layers', layers);
  console.log('newPositions', newPositions);

  let filtergraph = '';

  for (let i = 0; i < layers.length; i++) {
    const { top, left, width, height } = layers[i];
    const { width: newWidth, height: newHeight } = newPositions[i];
    const filter = `[0]crop=${width}:${height}:${left}:${top},scale=${newWidth}:${newHeight}[v${i}];`;
    filtergraph += filter;
  }

  for (let i = 0; i < layers.length; i++) {
    if (i === 0) {
      filtergraph += `[0][v${i}]overlay=`;
    } else {
      filtergraph += `[o${i-1}][v${i}]overlay=`;
    }
    const { top: newTop, left: newLeft } = newPositions[i];
    let overlay = '';
    if (i !== layers.length - 1) {
      overlay = `${newLeft}:${newTop}[o${i}];`;
    } else {
      overlay = `${newLeft}:${newTop};`;
    }
    filtergraph += overlay;
  }

  filtergraph = filtergraph.slice(0, -1); // remove last comma
  filtergraph += `[o${layers.length-1}]`;
  
  console.log('filtergraph', filtergraph);

  const ffmpeg = spawn(ffmpegPath, [
    '-i', videoFile,
    '-filter_complex', filtergraph,
    '-map', `[o${layers.length-1}]`,
    '-c:v', 'libx264',
    '-preset', 'ultrafast',
    '-crf', '18',
    '-y',
    path.join(outputDir, `${outputName}`)
  ]);  

  ffmpeg.stdout.on('data', (data) => {
    console.log(`FFmpeg output: ${data}`);
  });

  ffmpeg.stderr.on('data', (data) => {
    console.error(`FFmpeg error: ${data}`);
  });

  ffmpeg.on('close', (code) => {
    console.log(`FFmpeg process exited with code ${code}`);
    // event.reply('ffmpeg-export-done'); // Notify the renderer process
  });
});

我现在遇到的问题是，它覆盖了原始输入的区域，并保持了景观尺寸，而不是制作一个肖像视频。