微软Azure的多媒体编码服务示例

这篇文章是介绍 Azure 媒体服务编程系列之一。以前的主题是如何： 获得媒体处理器.

为服务器上的媒体内容，可以对内容与大量的媒体编码和格式使用 Azure Media 编码器进行编码。您还可以使用编码器提供的媒体服务的合作伙伴 ；第三方编码器可以使用通过Azure 市场。您可以指定编码任务，通过使用编码器预设的字符串，或通过使用配置文件的详细的信息。

MP4 自适应比特率集

编码，建议你到夹层文件到 MP4 自适应比特率设置，然后使用动态的包装，以提供您的内容。更多的信息，请参阅创建与媒体服务 SDK.net 编码作业、动态打包和交付内容.

MP4 编码

下面的方法将上载单个资产并创建作业，以编码到 MP4 使用资产"H264 宽带 720 p"预设，将创建一个单一的 MP4 使用 H264 编码在 720p 分辨率：

    static IJob CreateEncodingJob(string inputMediaFilePath, string outputFolder)
    {
        //Create an encrypted asset and upload to storage.
        IAsset asset = CreateAssetAndUploadSingleFile(AssetCreationOptions.StorageEncrypted,
            inputMediaFilePath);

        // Declare a new job.

        IJob job = _context.Jobs.Create("My encoding job");

        // Get a reference to the Azure Media Encoder
        IMediaProcessor processor = GetLatestMediaProcessorByName("Azure Media Encoder");

        // Create a task with the encoding details, using a string preset.
        ITask task = job.Tasks.AddNew("My encoding task",
            processor,
            "H264 Broadband 720p",
            _protectedConfig);

        // Specify the input asset to be encoded.
        task.InputAssets.Add(asset);

        // Add an output asset to contain the results of the job.
        // This output is specified as AssetCreationOptions.None, which
        // means the output asset is in the clear (unencrypted).
        task.OutputAssets.AddNew("Output asset", AssetCreationOptions.None);

        // Use the following event handler to check job progress.
        job.StateChanged += new EventHandler<JobStateChangedEventArgs>(StateChanged);

        // Launch the job.
        job.Submit();

        // Optionally log job details. This displays basic job details
        // to the console and saves them to a JobDetails-JobId.txt file
        // in your output folder.
        LogJobDetails(job.Id);

        // Check job execution and wait for job to finish.
        Task progressJobTask = job.GetExecutionProgressTask(CancellationToken.None);
        progressJobTask.Wait();

        // If job state is Error, the event handling
        // method for job progress should log errors.  Here we check
        // for error state and exit if needed.
        if (job.State == JobState.Error)
        {
            Console.WriteLine("\nExiting method due to job error.");
            return job;
        }

        // Perform other tasks. For example, access the assets that are the output of a job,
        // either by creating URLs to the asset on the server, or by downloading.
        return job;
    }

    private static void StateChanged(object sender, JobStateChangedEventArgs e)
    {
        Console.WriteLine("Job state changed event:");
        Console.WriteLine("  Previous state: " + e.PreviousState);
        Console.WriteLine("  Current state: " + e.CurrentState);
        switch (e.CurrentState)
        {
            case JobState.Finished:
            Console.WriteLine();
            Console.WriteLine("Job is finished. Please wait while local tasks or downloads complete...");
            break;
            case JobState.Canceling:
            case JobState.Queued:
            case JobState.Scheduled:
            case JobState.Processing:
                Console.WriteLine("Please wait...\n");
                break;
            case JobState.Canceled:
            case JobState.Error:

                // Cast sender as a job.
                IJob job = (IJob)sender;

                // Display or log error details as needed.
                LogJobStop(job.Id);
                break;
            default:
                break;
        }
    }

流媒体编码

如果你想要对某个光媒体的视频编码有两个选项：

• 直接编码为流媒体
• 编码为 MP4，然后转换为流媒体

直接编码为流媒体使用以上所示的代码，但使用流媒体编码器预设之一。编码器预设的完整列表，请参见任务预设字符串 Azure 媒体编码器.

若要将 MP4 转换为流媒体，请使用 Azure 媒体包。Azure 媒体包装不支持字符串预设，因此你必须在 XML 中指定的配置选项。可以在任务预设 Azure 媒体包装找到 MP4 转换为流媒体所需的 XML。复制并粘贴到您的项目中名为 MediaPackager_MP4ToSmooth.xml 的文件的 XML。下面的代码演示如何将 MP4 资产转换为流媒体。下面是一个简单示例：

private static IJob ConvertMP4toSmooth(IAsset assetToConvert, string configFilePath)
 {
    // Declare a new job to contain the tasks
    IJob job = _context.Jobs.Create("Convert to Smooth Streaming job");
    // Set up the first Task to convert from MP4 to Smooth Streaming.
    // Read in task configuration XML
    string configMp4ToSmooth = File.ReadAllText(Path.GetFullPath(configFilePath + @"\MediaPackager_MP4ToSmooth.xml"));
    // Get a media packager reference
    IMediaProcessor processor = GetLatestMediaProcessorByName("Azure Media Packager");
    // Create a task with the conversion details, using the configuration data
    ITask task = job.Tasks.AddNew("My Mp4 to Smooth Task",
           processor,
           configMp4ToSmooth,
           TaskOptions.None);
    // Specify the input asset to be converted.
    task.InputAssets.Add(assetToConvert);
    // Add an output asset to contain the results of the job.
    task.OutputAssets.AddNew("Streaming output asset", AssetCreationOptions.None);
    // Use the following event handler to check job progress.
    // The StateChange method is the same as the one in the previous sample
    job.StateChanged += new EventHandler<JobStateChangedEventArgs>(StateChanged);
    // Launch the job.
    job.Submit();
    // Check job execution and wait for job to finish.
    Task progressJobTask = job.GetExecutionProgressTask(CancellationToken.None);
    progressJobTask.Wait();
    // Get a refreshed job reference after waiting on a thread.
    job = GetJob(job.Id);
    // Check for errors
    if (job.State == JobState.Error)
    {
        Console.WriteLine("\nExiting method due to job error.");
    }
    return job;
}