在Windows Azure Media Services中上载和编码音频文件

Question

无处不在网上，我可以找到与上传到Azure媒体服务的视频文件相关的一些解释。

根据教程，我编写了自己的代码。

运行StoreAudio方法后，我有：

• 存储上的新Blob
• 媒体服务新资产
• 新作业在Media Services上成功完成
• 创建的资产未发布
• 当我尝试从像ID或URI这样的convertedAsset属性中获取时，我得到一个异常

为什么ID和URI为空？ 为什么内容“未发布”？

码：

public string StoreAudio(int ID, byte[] file)
    {
        try
        {
            var blobContainerName = AudioBookContainer; //+ AudioChapterID % 1000?
            var fileName = ID + ".mp3";

            var mediaBlobContainer = blobClient.GetContainerReference(blobContainerName);
            mediaBlobContainer.CreateIfNotExists();

            using (MemoryStream ms = new MemoryStream(file))
            {
                var reference = mediaBlobContainer.GetBlockBlobReference(fileName);
                reference.UploadFromStream(ms);
            }

            IAsset asset = _context.Assets.Create(fileName, AssetCreationOptions.None);
            IAccessPolicy writePolicy = _context.AccessPolicies.Create("writePolicy", TimeSpan.FromMinutes(120), AccessPermissions.Write);
            ILocator destinationLocator = _context.Locators.CreateLocator(LocatorType.Sas, asset, writePolicy);
            Uri uploadUri = new Uri(destinationLocator.Path);
            string assetContainerName = uploadUri.Segments[1];
            CloudBlobContainer assetContainer = blobClient.GetContainerReference(assetContainerName);

            var sourceCloudBlob = mediaBlobContainer.GetBlockBlobReference(fileName);
            sourceCloudBlob.FetchAttributes();
            if (sourceCloudBlob.Properties.Length > 0)
            {
                IAssetFile assetFile = asset.AssetFiles.Create(fileName);
                var destinationBlob = assetContainer.GetBlockBlobReference(fileName);
                destinationBlob.DeleteIfExists();
                destinationBlob.StartCopyFromBlob(sourceCloudBlob);
                destinationBlob.FetchAttributes();
                if (sourceCloudBlob.Properties.Length != destinationBlob.Properties.Length)
                    throw new Exception("Error copying");
            }
            destinationLocator.Delete();
            writePolicy.Delete();

            asset = _context.Assets.Where(a => a.Id == asset.Id).FirstOrDefault();  //At this point, you can create a job using your asset. 
            var encodedAsset = EncodeToWMA(asset);
            return encodedAsset.Id;

            //var ismAssetFiles = encodedAsset.AssetFiles.ToList().Where(f => f.Name.EndsWith(".ism", StringComparison.OrdinalIgnoreCase)).ToArray();  
            //if (ismAssetFiles.Count() != 1)     
            //    throw new ArgumentException("The asset should have only one, .ism file");  

            //ismAssetFiles.First().IsPrimary = true; 
            //ismAssetFiles.First().Update();

            asset.Delete();

            return encodedAsset.Uri.AbsoluteUri;                
        }
        catch(Exception exx)
        {
            return exx.Message + exx.InnerException;
        }
    }


 private static IMediaProcessor GetLatestMediaProcessorByName(string mediaProcessorName)
    {
        var processor = _context.MediaProcessors.Where(p => p.Name == mediaProcessorName).ToList().OrderBy(p => new Version(p.Version)).LastOrDefault();
        if (processor == null)
            throw new ArgumentException(string.Format("Unknown media processor", mediaProcessorName));
        return processor;
    }

    public static IAsset EncodeToWMA(IAsset asset)
    {
        IJob job = _context.Jobs.Create("Convert MP3 to WMA");
        IMediaProcessor processor = GetLatestMediaProcessorByName("Windows Azure Media Encoder");
        ITask task = job.Tasks.AddNew("My encoding task", processor, "WMA High Quality Audio", TaskOptions.None);
        task.InputAssets.Add(asset);
        task.OutputAssets.AddNew(asset.Name.Replace(".mp3", ".wma"), AssetCreationOptions.None);
        job.Submit();
        Task progressJobTask = job.GetExecutionProgressTask(CancellationToken.None);
        progressJobTask.Wait();
        return task.OutputAssets.First();
    }

Answer 1

对于音频文件，您可以要求SAS定位器访问文件 - SAS定位器用于渐进式下载。

_context.Locators.Create（LocatorType.Sas，outputAsset，AccessPermissions.Read，TimeSpan.FromDays（30））;

Answer 2

添加更多说明：

我建议你创建SAS定位器是因为我们现在不支持WMA文件的音频流，因此，获取Origin Streaming定位器对你不起作用。

资产“未发布”的原因：您从未发布资产 - 获取SAS定位器或Origin定位器是获取资产的方式。