Review: Telestream Vantage Transcode Multiscreen
Vantage Transcode Multiscreen software, running on the new Lightspeed Server, produced very high-quality video in a range of single-file and adaptive bitrate (ABR) formats. Performance was dependent upon the type of task being performed and ranged from so-so to promising. As a part of the Vantage Workflow system family, Transcode Multiscreen and the Lightspeed Server are valuable additions; you can see a discussion of the Vantage Workflow system in this Notre Dame case study
. If you’re looking for the fastest encoding engine in the land, however, you should definitely look elsewhere.
Products and Pricing
Vantage Transcode Multiscreen is a GPU-accelerated workflow system with support for a range of ABR formats, including Apple HTTP Live Streaming (HLS), HTTP-based Dynamic Streaming (HDS), Microsoft Smooth Streaming, and DASH. It ships solely as a bundle with Telestream’s new Lightspeed Server, a 1RU rack-mounted system with multiple GPU and CPU cores designed to accelerate Transcode Multiscreen. Total system cost is $26,000.
The Test Configuration
I tested the system by logging in via a remote desktop connection. The Lightspeed System was running Windows Server 2008 R2 Standard, driven by dual 2.0 GHz E5-2650 Xeon processors, with 8/16 cores each (with HTT) with 32GB of RAM. The graphics card was a Matrox G200eW, and GPU horsepower was provided by two NVIDIA Tesla M2075 CUDA cards.
You drive the Multiscreen encoder through the Vantage Workflow software, where it shows up as a codec building block in the top toolbar. Architecturally, Vantage works around the concept of a workflow, which you create using graphical elements in the Workflow Designer shown in Figure 1.
Figure 1. The graphics components of a simple workflow in the Multiscreen encoder
If you look closely, you’ll note that icons on the top right of each element identify the function that the element will perform. For example, in Figure 1, The Watch element is scanning a watch folder for incoming files to submit to the Multiscreen Flip, while the Receive function lets you manually load a file into the workflow. The Multiscreen Flip is the element that deploys the Multispeed encoder running on the Lightspeed encoder. After encoding is complete, the files are sent to the Deploy function for delivery.
You build a workflow by dragging a workflow building block from the icons on the top and connecting the elements in the Workflow Designer. Once inserted into a workflow, each element offers extensive configuration options that finely detail the task performed. For example, in Figure 2, you see the three high-level configuration options available in the Multiscreen Flip module, Inputs, Transcoders, and Outputs.
Figure 2. The three high-level configuration options in the Multiscreen Flip module
The Inputs function defines and names the elements of the incoming file, in this case, Video 1 and Audio 1. The Transcodes function grabs the discrete elements of the incoming file and encodes them into single audio and video files, essentially elementary streams. For example, in Figure 3, you see that Audio 1 is sent to an AAC transcoder where it’s converted into two files, one at 128Kbps and one at 96Kbps.
Figure 3. Converting the incoming audio and video into elementary streams using different encoding parameters
Similarly, the Video 1 file is sent to multiple x264 converters, some encoded into a single resolution, some encoded into multiple versions at multiple resolutions. For example, in addition to unique streams at 720p and 768x432, this adaptive group encodes four streams around the 640x360 configuration, at 240, 540, 740, and 1200Kbps.
Since I’m starting with a 720p file, getting to 640x360 involves scaling and, for some source files, deinterlacing and other filtering as well. Rather than processing each file in the adaptive group individually, Vantage processes all files produced at the same resolution at one time, performing all scaling, deinterlacing, and other filtering once and then encoding the output four separate times. Most other encoders would encode each file separately, performing the scaling, deinterlacing, and other filtering each time, which is less efficient.
Vantage uses the x264 codec with familiar presets and tuning profiles and a few key adjustments available in the GUI (Figure 4). If you really want to tweak the controls, you can drop in a command line argument and access all x264 parameters.
Figure 4. Vantage’s encoding controls
You apply all encoding parameters except data rate to each transcoder instance, essentially each resolution produced by the encoder. For example, in Figure 3, you would set all encoding parameters except the data rate in each of the three x264 boxes. Then you would set the data rate for each iteration at that resolution within the box separately.
Packaging the Elementary Streams
Once the elementary streams are created, Vantage can incorporate them into multiple output files, as shown in Figure 5. There you see the same elementary screens packaged into two different output variants for HDS and HLS. Building these variants is simplified by drop-down lists that expose the elementary streams encoded in the previous step. Just click the Plus sign to add a variant, type in the name (or copy/paste/edit the name), and choose the desired elementary streams in the drop-down list.
Figure 5. Packing the elementary streams into multiple outputs
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Companies and Suppliers Mentioned