What is Transcoding?
Transcoding is the process of converting or "encoding" an uploaded or ingested media file to a compressed streaming MP4 file. The resulting video file is referred to as an encoding.
A transcoding Preset is a recipe for transcoding content to a stream-able format. For example, there are presets for converting uploaded media to 480p, 720p, and 1080p MP4 video formats.
A transcoding Profile contains one or more presets. A transcoding profile is specified in Ensemble Video Upload Workflows to control how content uploaded in a particular Library with a particular Workflow will be transcoded (Transcoding profiles can also be used for other workflows, but for most other workflows no transcoding is necessary. For Upload workflows transcoding is almost always necessary).
A wide variety of transcoding presets are included with your Ensemble Video installation, and transcoding Profiles are created and edited in the System->Admin->Transcoding Profiles Interface.
A transcoding profile can contain a single encoding preset -- for example many Ensemble Video customers use a "Compress and Stream" transcoding profile that contains a single preset and only one encoding is created during transcoding.
A transcoding profile can also have multiple recipes, to product multiple encodings on output. This is for Adaptive Bit-Rate (ABR) streaming.
Adaptive Bit-Rate Profiles
With adaptive bit rate streaming (ABR), Ensemble video player can automatically switch between multiple video encodings during streaming playback to ensure the best video quality for the available bandwidth. If you haven't already, we recommend upgrading to a High-Definition Adaptive Bit-Rate transcoding profile.
1080p - 4.2 Mbps
480p - 1.8 Mbps
320p - 900 Kbps
If you have a need to serve content to a population that has very constrained bandwidth, you can drop down the lowest version to 270p (this is typically only needed in special cases where there a large, known contingent of bandwidth constrained viewers). You can also swap out the 480p for a 720p encoding, this will use a bit more storage, but will provide the best chance of viewers seeing a high-definition version of your videos.
If you prefer to stick with a transcoding profile that produces a single encoding, to limit storage requirements (usually identified as a "Compress and stream" profile), we recommend you use:
480p - 1.8 Mbps
With Ensemble Transcoder Custom Presets are Usually Not Needed
Today's transcoding engines will convert content without resizing unless absolutely necessary. Older transcoding technology would force reformatting, and as a result some customers created many types of transcoding profiles to handle different types of input files. Those additional transcoding profiles are no longer needed.
Standard presets included with Ensemble Transcoder include 270p, 360p, 480p, 720p and 1080p at appropriate bit rates for your content. When you upgrade to Ensemble Video Transcoder you can convert any older transcoding profiles which are no longer needed to one of the included 16:9 profiles based on bit rate.
Editing a Transcoding Profile
If for some reason you find you need to edit an existing Transcoding Profile, and it will be updated for all Ensemble Video Workflows that reference that Profile. This enables you to do system-wide update of an existing ABR HQ transcoding profile to an ABR HD profile, for example, or change existing Compress and Stream 360p transcoding profile with a 480p transcoding profile.
Please note, when creating or editing a ABR profile, Use Ctrl-click to select multiple ABR presets. You should choose among presets labelled ABR HD when creating an ABR Profile. They are designed to be used together, and your viewers won't notice any video issues as the player switches between the various encodings. The Default encoding is the encoding that will start when the video playback begins. It is best to use as Default one of the lower bit rate formats, if you use the highest quality encoding as default then users on constrained networks will immediately see buffering.