In case you’re attempting to stream video, you’ve undoubtedly heard the phrases “encoding” and “transcoding” thrown round — however what’s the distinction, and what does it matter?

Basically, encoding is the act of compressing uncooked video right into a extra manageable format, whereas transcoding refers to taking already-compressed footage and altering it (reminiscent of to make it extra transmittable to totally different audiences). They’re very totally different processes that serve distinctive functions, so let’s dive into why they’re each necessary and find out how to know when every is suitable.

First, A Few Definitions

Earlier than we go ahead, some definitions you’ll have to know embody:

Video encoding: To elaborate on the purpose above, this time period describes the method of changing uncooked video — which is way too massive to broadcast or stream in its authentic state when a digital camera captures it — right into a compressed format that makes it doable to transmit throughout the web.

With out video encoding, there could be no streaming. It’s step one in delivering content material to an internet viewers as a result of it’s what makes video digital.

Codec: Encoding depends on two-part compression expertise referred to as codecs. Quick for “coder-decoder” or “compressor-decompressor” (we love a great double that means), codecs use algorithms to discard visible and audio knowledge that gained’t have an effect on a video’s look to the human eye. As soon as video information are a extra manageable dimension, it’s possible to stream them to audiences and decompress them once they attain totally different gadgets.

In case you’re confused in regards to the distinction between codecs and encoders consider it this fashion: encoders are {hardware} (like Teradek) or software program (like OBS Studio) that carry out the motion of encoding by utilizing codecs. H.264/AVC, HVEC, and VP9 are widespread video codecs you’ll come throughout (H.264 most of all), and AAC, MP3, and Opus are examples of audio codecs.

Decoding: Decoding is the act of decompressing encoded video knowledge to show or alter it not directly. For instance, a human viewer can’t watch an encoded video, so their machine should decode the information and reassemble the “packets” in the suitable order to show it on a display. 

Transcoding: Transcoding is an umbrella time period that refers to taking already-encoded content material, decoding/decompressing it, implementing alterations, and recompressing it earlier than last-mile supply. Transcoding video would possibly contain making smaller adjustments, reminiscent of including watermarks and graphics; or a lot bigger ones, like changing content material from one codec to a different. Actions like transrating and transizing fall underneath the definition of transcoding.

Transcoding typically falls proper within the center alongside the digital camera to end-user pipeline. A possible use case could be making use of a protocol like RTMP, RTSP, SRT, or WebRTC  for first-mile supply to a transcoder — which might be both a media server or cloud-based streaming platform — after which transcoding your content material into a distinct codec (or a number of codecs) to make it appropriate with the sorts of protocols your viewers’s gadgets help. These embody protocols like Apple HLS, MPEG-DASH, HDS, and WebRTC (which is relevant for each first and final mile).

Transmuxing: You’ve additionally doubtless heard the time period “transmuxing,”which refers to repackaging, rewrapping, or packetizing content material. Transmuxing is to not be confused with transcoding as a result of the previous includes switching supply codecs whereas the latter requires extra computational energy and makes adjustments to the content material itself.

When You Must Encode Video

You encode video since you want it to be, nicely, smaller — which suggests it’s inevitable.

Keep in mind that scene from Willy Wonka and the Chocolate Manufacturing unit when Mike Teavee jumps in entrance of the Wonkavision machine and seems in a TV throughout the room, now two inches tall? The machine took his bigger self, broke him down into numerous tiny items, transmitted them via the air, and reassembled him the suitable means (adjusting for the TV’s smaller dimension). Poor Mike was encoded and delivered.

Encoding can compress gigabytes value of knowledge into mere megabytes. The method might happen in:

• Cell apps
• IP cameras
• Encoding software program
• Specialised {hardware}

Throughout a reside stream, these instruments encode footage as quickly because the cameras they’re related to seize it. The video knowledge is now able to bear no matter extra processes are essential to make it deliverable to varied finish customers.

When Transcoding Video Is Needed

Transcoding video is an even bigger query as a result of encoding occurs 100% of the time, however transcoding isn’t explicitly essential to stream to viewers. 

Why so? It is dependent upon your viewers. As an example, reside streaming footage from surveillance cameras on a non-public community, like at a museum, gained’t require transcoding as a result of solely safety guards will see it. All of their instruments and screens are on-site or related to exterior gadgets on the museum’s community.

Equally, in case you’re streaming to a broader viewers and wish to ship your content material utilizing the SRT protocol, you have to make sure each particular person you’ll be streaming to makes use of a tool or media participant with the suitable playback compatibility, like Haivision Play or Brightcove.

It’s unlikely that’s a assure you can also make, although. Think about you wish to reside stream a highschool commencement occasion (that are infamous for providing minimal in-person tickets per pupil, which suggests some family members have to look at from dwelling). You need grandparents in rural Kansas, utilizing a barely older laptop and poor web, to have the ability to watch their grandchild cross the stage simply as seamlessly as another person’s aunt and uncle who reside in New York with a high-speed connection on the most recent MacBook. To make this occur, you’ll have to transcode.

What Occurs Throughout Transcoding?

Encoding is step one throughout this hypothetical reside stream. You’ll doubtless use a extra extensively supported codec and supply protocol, like H.264 and Apple HLS, respectively. These choices shouldn’t current any issues, however if you wish to ship the content material at a 1080p decision, then our Kansas grandparents are in for a substantial amount of frustration as they await the participant to buffer over and over.

So, you’ll want to alter the bitrate to accommodate their restricted bandwidth. You’ll be able to ship the stream to a reside transcoder that:

1. Decodes the information
2. Creates a number of time-aligned streams with optimized body sizes and bitrates
3. Probably converts them to totally different codecs
4. Re-encodes them
5. Adjusts supply protocols

All to allow adaptive streaming that performs on screens of any sort. The extra decision and bitrate choices you present, the less issues viewers will encounter when attempting to look at your stream.

How Do Encoding And Transcoding Have an effect on Video High quality?

You’re understandably interested in how encoding and transcoding have an effect on video high quality. It sounds such as you’re placing video knowledge via the wringer, so what’s the probability it is going to come out the opposite finish as you envisioned it?

Encoding and transcoding can have an effect on video high quality, however don’t must. As we’ve talked about, compressing video includes eradicating knowledge with out excessively damaging its high quality. If compress a video simply the correct amount, the ultimate end result gained’t be perceptible to the human eye; compress a video an excessive amount of, and also you’ll have a pixelated picture and glitchy sound.

How Encoding Impacts High quality

There are two sorts of encoding:

Lossy compression: Decreasing a file dimension by discarding pointless knowledge.

Lossless compression: Compacting information with out the above course of, subsequently sustaining knowledge integrity. ZIP information are an instance.

Encoding video, particularly, is an inherently lossy course of. It’s necessary to concentrate on your rate-distortion tradeoff: your video’s high quality will often correspond to the bitrate’s dimension. This isn’t at all times the case — the sort of content material you’re compressing issues, like live-action footage versus animation — but it surely’s a great rule of thumb. One of the simplest ways to compensate for a smaller bitrate is to decrease the decision so pictures don’t seem overly grainy.

How a Transcoder Impacts High quality

There are additionally three sorts of transcoding (strive saying these all 5 instances quick):

Lossless-to-lossless: Compressing a file that hasn’t misplaced any data and transcoding it in such a means that nothing else is eliminated a second time. Technically doable, however will doubtless lead to a big file dimension that streaming or broadcasting is moot. You’ll have to make use of a high-end transcoder to attain this end result.

Lossy-to-lossy: This type of transcoding means you’re additional degrading an already low-quality video.

Lossless-to-lossy: Compressing a lossless file after altering it, this time eradicating pointless knowledge.

Whichever technique you select will have an effect on your video’s high quality, so pay attention to what sort of gadgets you wish to stream to and what knowledge you wish to add or subtract.

Your Choices for an Encoder or Transcoder

Subsequent, the place do you flip to for encoding and transcoding? Encoders might be {hardware} or software program that converts video indicators coming from digital camera sensors. You’ll be able to be taught all about what to search for in an encoder right here.

Transcoding software program might be both native or cloud-based. Native transcoders are slower however you should utilize them on-site. Cloud transcoders like Wowza’s, then again, are quicker and allow you to transcode 4K decision and stream with out worrying about how nicely it is going to playback for grandparents in rural Kansas or anybody conveniently dwelling subsequent to a CDN in New York.

Encoding and Transcoding With Wowza

There’s no room for error relating to optimizing your content material’s playback. Thankfully, Wowza’s expertise helps and allows all types of compression, alteration, and decompression you have to stream to as broad an viewers as doable. No matter sort of encoder or transcoder you’re on the lookout for, Wowza has the expertise and ecosystems of instruments to make it occur.

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Extra Assets:

• What Is Transcoding and Why Is It Essential
• Video Transcoding Outlined
• What Is Video Encoding

About Jacob Yoss

Jacob is Wowza’s resident Content material Author, creating weblog posts, case research, and extra that educate Wowza’s viewers. Born and raised in Denver, Colorado, Jacob at present travels the world as a digital nomad and can be obsessed with social justice, artwork,… View extra