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 Video Transcoding: What It Is and How It Works
September 22, 2022

Video Transcoding: What It Is and How It Works

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Transcoding permits broadcasters to transform stay and on-demand streams utilizing a streaming software program or service to optimize content material for every step of the workflow. This ensures higher accessibility, improved efficiencies, and a better high quality expertise — whereas minimizing prices and complexity on the encoding stage.

Learn on to be taught what video transcoding is, the way it works, and why it’s important to most streaming workflows.



What Is Video Transcoding?

Video transcoding entails decompressing an encoded video file, (usually) altering it, after which recompressing — doubtlessly in a unique encoding format — for supply to finish customers. This conversion course of can happen on the media server or in a cloud-based streaming platform. By transcoding, content material distributors can re-encode the information right into a extra widespread codec, transize the video right into a decrease decision, or transrate the file right into a decrease bitrate.


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Let’s break down that trio of Ts:

  • Video Transcoding: An umbrella time period for changing a video/audio file by way of a multi-step technique of decompressing an encoded file, probably manipulating it not directly, and recompressing for supply. Transrating and transizing are each subcategories of transcoding.
    • Transrating: Altering the bitrate of the decompressed file to accommodate completely different connection speeds. This allows extra environment friendly storage and supply by lowering the file measurement.
    • Transizing: Resizing the video body to accommodate completely different screens. This permits broadcasters to regulate the decision for supply to varied gadgets.


Why Transcode a Reside Stream?

So now that we all know what it’s, why is video transcoding crucial? And why not simply encode the stream into its remaining codec, decision, and bitrate to start with?

It has to do with the truth that the perfect streaming codecs and configurations for first-mile contribution aren’t at all times the perfect for last-mile supply. What’s extra, creating a number of video renditions on the encoder to help adaptive bitrate (ABR) streaming is much less environment friendly and economical than doing so utilizing a video transcoding answer.

For example, say you wish to convert a single-bitrate Net Actual-Time Communications (WebRTC) supply stream into a number of output renditions that will likely be performed again over HTTP Reside Streaming (HLS). The advantages of this workflow are a lot. Sticking with WebRTC on the ingest aspect would allow low-latency and browser-based contribution. From there, transcoding the stream into multi-bitrate HLS would guarantee large-scale supply by way of a content material supply community (CDN), playback help on numerous gadgets, and a high-quality expertise for viewers no matter their connectivity.

Video transcoding would play an important position in harnessing the advantages of a WebRTC to HLS workflow. And also you’d possible wish to use a streaming server or cloud-based streaming platform for the heavy lifting.


What Processes Happen Throughout Video Transcoding?

Extra particularly, a stay streaming platform like Wowza is important for the next video transcoding processes:

  1. Codec conversion: WebRTC and HLS use completely different audio codecs, so a stay transcoder would assist you to change the incoming Opus audio to a extra typical format like AAC.
  2. Creating a number of output renditions: Adaptive bitrate streaming requires broadcasters to stream a number of renditions concurrently. A video transcoding answer lets broadcasters convert the only supply stream into a wide range of decision and bitrate choices, enabling every viewer to play the highest-quality stream accessible for his or her machine and connection velocity. Even higher, the stream will dynamically modify to ship a superior rendition if a viewer’s connectivity improves.
  3. Including graphics: Since WebRTC allows browser-based encoding, broadcasters trying to embrace extra graphics of their stay stream would possibly select to take action on the streaming server. Decrease-third overlays, watermarks, and logos can all be added throughout video transcoding.
  4. Transmuxing: Transmuxing happens when a media server ingests the compressed video information and repackages it into a unique container format. On this instance, the stream is repackaged from WebRTC to HLS. Content material distributors can thereby ship the stream to extra gadgets utilizing numerous protocols with out manipulating the precise file.



Steps one, two, and three are examples of transcoding. The fourth step, transmuxing, doesn’t necessitate decompressing and recompressing the stream. Because of this, it’s much less computationally intensive than transcoding. On this case, nevertheless, transcoding the codec was an important first step to repackaging the stream.


How one can Transcode Reside Video Streams With Wowza

We designed our stay streaming software program and companies to make transcoding a snap. There are quite a few stay transcoding workflows supported in each Wowza Streaming Engine and Wowza Streaming Cloud. Beneath we’ve included a how-to tutorial on the structure illustrated above: changing WebRTC to adaptive bitrate HLS.


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Advantages of Video Transcoding

Video transcoding advantages everybody by maintaining your content material optimized for every stage of the streaming lifecycle. Listed below are the obstacles that transcoding eliminates for broadcasters and viewers.

On the publishing aspect, video transcoding resolves:

  • Excessive prices and complexity related to encoding a number of completely different decision and bitrate choices.
  • Restricted playback capabilities primarily based on the codecs, protocols, and configurations accessible within the encoder.
  • Lack of ability to leverage next-generation applied sciences and hybrid workflows.

On the viewer aspect, video transcoding resolves:

  • Buffering because of low-bandwidth connections.
  • Incompatibility because of missing format help.
  • Playback failure because of missing machine help for the decision streamed.
  • Low-quality supply to end-users with higher connectivity and determination capabilities than that of the stream delivered.


Encoding vs. Transcoding: What’s the Distinction?


1. Encoding happens first; transcoding happens second.

This one is likely to be apparent, however to belabor the purpose: Simply as one should write a guide earlier than translating a guide, a stream should be encoded earlier than it may be transcoded.

Consider the 2 because the steps concerned when packing for a trip. Initially, you compress (encode) your clothes right into a bag for straightforward transportation to wherever you’re headed. When you arrive at your vacation spot, you unpack, discard the gadgets you now not want (like that vacant toothpaste tube), add trinkets gathered throughout your travels, after which repack your bag for the subsequent step of your journey. That is transcoding.


2. Encoding is critical; transcoding won’t be.

It’s not doable to stay stream a video over the web with out encoding. This technique of condensing uncooked video right into a digital format for environment friendly supply throughout the online at all times happens, even when the encoder is constructed into the seize machine you’re broadcasting from.

Video transcoding, then again, isn’t do-or-die. Loads of workflows, comparable to these utilizing WebRTC from finish to finish, don’t require any transcoding infrastructure. A stream can be transformed from RTMP to HLS with out requiring video transcoding — however you’d miss out on adaptive bitrate streaming with out transcoding the only high-bitrate RTMP stream right into a multi-bitrate encoding ladder, which is a prime driver for utilizing HLS.



If each viewer had a 4K dwelling theater plugged into high-speed web, delivering video content material could be straightforward. However that’s not the case. At this time’s viewers are out and about, accessing streams from a wide range of gadgets. Totally different screens and ranging web speeds make video transcoding and processing important. Plus, this performance means that you can repackage content material into numerous codecs for dependable playback on any machine. Selecting a streaming platform like Wowza that provides protocol flexibility and adaptive bitrate supply will make sure that your streams play again seamlessly throughout many endpoints.


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Why Wowza

With greater than a decade of expertise powering video for 35,000 plus organizations, Wowza’s full-service platform is the gold normal for stay video transcoding. Our on-the-fly expertise ensures interoperability throughout all gadgets and high-quality streaming for all connection speeds — whereas maintaining issues easy on the encoder.


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Further Assets:

  • The Full Information to Reside Streaming
  • Video Codecs and Encoding
  • Streaming Protocols

About Traci Ruether

As a Colorado-based B2B tech author, Traci Ruether serves as Wowza’s content material advertising supervisor. Her background is in streaming and community infrastructure. Other than writing, Traci enjoys cooking, gardening, and spending high quality time together with her kith and kin. Comply with her… View extra

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