AWS Lambda函数用于剪辑视频，可以执行以下步骤：

1. 安装AWS CLI并创建IAM角色：

aws iam create-role --role-name lambda-cli-role --assume-role-policy-document file://trust-policy.json

aws iam attach-role-policy --role-name lambda-cli-role --policy-arn arn:aws:iam::aws:policy/AmazonS3FullAccess

2. 创建AWS Lambda函数：

aws lambda create-function --function-name trim-video --runtime nodejs12.x --role arn:aws:iam::123456789012:role/lambda-cli-role --handler index.handler --zip-file fileb://./trim-video.zip --timeout 60

3. 在AWS Lambda中编写以下Node.js代码：

exports.handler = async(event) => {

    const sourceBucket = event.Records[0].s3.bucket.name;
    const sourceKey = event.Records[0].s3.object.key;
    const targetBucket = 'target-bucket';
    const targetKey = sourceKey.replace(/\.mp4$/, '-trimmed.mp4');

    const params = {
        FunctionName: 'ffmpeg-layer',
        Payload: JSON.stringify({
            sourceBucket: sourceBucket,
            sourceKey: sourceKey,
            targetBucket: targetBucket,
            targetKey: targetKey
        })
    };

    await lambda.invoke(params).promise();

    const s3 = new aws.S3();
    const response = await s3.getObject({
        Bucket: targetBucket,
        Key: targetKey
    }).promise();

    const data = await parseMeta(response.Body);
    console.log(data);

    const sns = new aws.SNS();
    const message = `Video trimmed: ${sourceKey} -> ${targetKey}\n${JSON.stringify(data, null, 2)}`;

    await sns.publish({
        TopicArn: 'arn:aws:sns:us-east-1:123456789012:my-topic',
        Message: message
    }).promise();
};

4. 使用FFmpeg Lambda层和Node.js的fluent-ffmpeg库来剪辑视频：

const FfmpegCommand = require('fluent-ffmpeg');

exports.handler = async(event) => {

    const { sourceBucket, sourceKey, targetBucket, targetKey } = event;
    const s3source = `s3://${sourceBucket}/${sourceKey}`;
    const s3target = `s3://${targetBucket}/${targetKey}`;

    const downloadCommand = new FfmpegCommand()
        .input(s3source)
        .audioCodec('copy')
        .videoCodec('copy')
        .output('pipe:');

    const