new topic

Author: Juliako

articles/media-services/latest/TOC.yml

@@ -138,6 +138,8 @@
     - name: Time-shifting and live-to-VOD
       displayName: archive, dvr
       href: live-event-cloud-dvr.md
+    - name: Live transcription
+      href: live-transcription.md
     - name: Feature comparison
       href: live-event-types-comparison.md
     - name: States and billing

articles/media-services/latest/live-transcription.md

@@ -0,0 +1,104 @@
+---
+title: Using Azure Media Services time-shifting and live-to-VOD (video on demand) | Microsoft Docs
+description: This article explains what Live Output is and how to use a cloud DVR.  
+services: media-services
+documentationcenter: ''
+author: Juliako
+manager: femila
+editor: ''
+
+ms.service: media-services
+ms.workload: media
+ms.tgt_pltfrm: na
+ms.devlang: ne
+ms.topic: article
+ms.date: 08/27/2019
+ms.author: juliako
+
+---
+
+# Live transcription (preview)
+
+Azure Media Service delivers video, audio, and now text in different protocols. When you publish your live stream using MPEG-DASH or HLS/CMAF, then along with video and audio, our service will deliver the transcribed text in IMSC1.1 compatible TTML, packaged into MPEG-4 Part 30 (ISO/IEC 14496-30) fragments. If using delivery via HLS/TS, then text is delivered as chunked VTT. 
+
+This article describes how to enable live transcription when streaming a Live Event with Azure Media Services v3. Before you proceed, make sure you are familiar with the use of Media Services v3 REST APIs (see [this tutorial](stream-files-tutorial-with-rest.md) for details). You should also be familiar with the [live streaming](live-streaming-overview.md) concept. It is recommended to complete the [Stream live with Media Services](stream-live-tutorial-with-api.md) tutorial). 
+
+> [!NOTE]
+> Currently, live transcription is only available as a preview feature in the West US 2 region. It supports transcription of spoken words in English to text. The API reference for this feature is in this document – since it is in preview, the details are not available with our REST documents. 
+
+## Creating the Live Event 
+
+To create the Live Event, you would send the PUT operation to the 2019-05-01 version, such as: 
+
+```
+PUT https://management.azure.com/subscriptions/:subscriptionId/resourceGroups/:resourceGroupName/providers/Microsoft.Media/mediaServices/:accountName/liveEvents/:liveEventName?api-version=2019-05-01-preview&autoStart=true 
+```
+
+The operation has the following body (where a pass-through Live Event is created with RTMP as the ingest protocol). Note the addition of a transcriptions property. The only allowed value for language is en-US. 
+
+```
+{ 
+  "properties": { 
+    "description": "Demonstrate how to enable live transcriptions", 
+    "input": { 
+      "streamingProtocol": "RTMP", 
+      "accessControl": { 
+        "ip": { 
+          "allow": [ 
+            { 
+              "name": "Allow All", 
+              "address": "0.0.0.0", 
+              "subnetPrefixLength": 0 
+            } 
+          ] 
+        } 
+      } 
+    }, 
+    "preview": { 
+      "accessControl": { 
+        "ip": { 
+          "allow": [ 
+            { 
+              "name": "Allow All", 
+              "address": "0.0.0.0", 
+              "subnetPrefixLength": 0 
+            } 
+          ] 
+        } 
+      } 
+    }, 
+    "encoding": { 
+      "encodingType": "None" 
+    }, 
+    "transcriptions": [ 
+      { 
+        "language": "en-US" 
+      } 
+    ], 
+    "vanityUrl": false, 
+    "streamOptions": [ 
+      "Default" 
+    ] 
+  }, 
+  "location": "West US 2" 
+} 
+```
+
+You should poll the status of the Live Event until it goes into the “Running” state, which indicates that you can now send a contribution RTMP feed. You can now follow the same steps as in this tutorial, such as checking the preview feed, and creating Live Outputs. 
+
+## Delivery and playback 
+
+Review the [Dynamic packaging overview](dynamic-packaging-overview.md#to-prepare-your-source-files-for-delivery) article of how our service uses dynamic packaging to deliver video, audio, and now text in different protocols. When you publish your live stream using MPEG-DASH or HLS/CMAF, then along with video and audio, our service will deliver the transcribed text in IMSC1.1 compatible TTML, packaged into MPEG-4 Part 30 (ISO/IEC 14496-30) fragments. If using delivery via HLS/TS, then text is delivered as chunked VTT. You can use a web player such as the [Azure Media Player](use-azure-media-player.md) to play the stream.  
+
+## Known issues 
+
+At preview, following are the known issues with Live Transcription 
+
+* The feature is available only in West US 2.
+* Applications need to use the preview APIs, described in the [Media Services v3 OpenAPI Specification](https://github.com/Azure/azure-rest-api-specs/blob/master/specification/mediaservices/resource-manager/Microsoft.Media/preview/2019-05-01-preview/streamingservice.json) specification.
+* The only supported language is English.
+* With respect to content protection, only AES envelope encryption is supported.
+
+## Next steps
+
+[Media Services overview](media-services-overview.md)