Set Content-type of media files stored on Blob

Unfortunately, the accepted answer here is not currently working for the latest SDK (12.x.+)

With the latest SDK, the content type should be set via BlobHttpHeaders.

var blobServiceClient = new BlobServiceClient("YOURCONNECTIONSTRING");
var containerClient = blobServiceClient.GetBlobContainerClient("YOURCONTAINERNAME");
var blob = containerClient.GetBlobClient("YOURFILE.jpg");

var blobHttpHeader = new BlobHttpHeaders { ContentType = "image/jpeg" };
 
var uploadedBlob = await blob.UploadAsync(YOURSTREAM, new BlobUploadOptions { HttpHeaders = blobHttpHeader });

YOURSTREAM could be a new BinaryData(byte[])

With Azure.Storage.Blogs (12.8.4), We can set content type of file as below. In Default, Azure Storage stores file in application/octet-stream, In case of *.svg file, doesn't properly render in html. So we have to save *.svg file in azure blob storage with content type image/svg+xml while uploading into blob.

Below is the code sample I got working.

  BlobServiceClient blobServiceClient = new BlobServiceClient("CONNECTIONSTRING");
  BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient("CONTAINERNAME");
  BlobClient blobClient = containerClient.GetBlobClient("BLOBNAME");
  try
  {

    Stream stream = file.OpenReadStream();
    await blobClient.UploadAsync(stream, true);
    blobClient.SetHttpHeaders(new BlobHttpHeaders() { ContentType = file.ContentType });
  }

ContentType Set on header should place just below the blobClient.UploadAsync().

This is work example to upload video to Azure Blob Storage with right Content-Type:

public static String uploadFile(
     CloudBlobContainer container,String blobname, String fpath) {

    CloudBlockBlob blob;
    try {
        blob = container.getBlockBlobReference(blobname);
        File source = new File(fpath);

        if (blobname.endsWith(".mp4")) {
            System.out.println("Set content-type: video/mp4");
            blob.getProperties().setContentType("video/mp4");
        }

        blob.upload(new FileInputStream(source), source.length());

        return blob.getUri().toString();
    } catch (URISyntaxException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (StorageException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return null;
}

This should work:

var storageAccount = CloudStorageAccount.Parse("YOURCONNECTIONSTRING");
var blobClient = storageAccount.CreateCloudBlobClient();

var blobs = blobClient
    .GetContainerReference("thecontainer")
    .ListBlobs(useFlatBlobListing: true)
    .OfType<CloudBlockBlob>();

foreach (var blob in blobs)
{
    if (Path.GetExtension(blob.Uri.AbsoluteUri) == ".mp4")
    {
        blob.Properties.ContentType = "video/mp4";
    }
    // repeat ad nauseam
    blob.SetProperties();
}

Or set up a dictionary so you don't have to write a bunch of if statements.