Your Ultimate Transcoding Glossary

Transcoding is an essential part of any video streaming workflow, but the transcoding process is also rife with terminology, some of it easily confused. Consider this your one-stop shop for all your transcoding knowledge. Start with your basic definitions and find links to the resources you need most.

   

4K Transcoding

4K transcoding specifically refers to transcoding 4K video into a smaller format by reducing the size, resolution, or both. 4K video is particularly resource demanding given its size and high resolution, making it uniquely challenging to transcode for delivery. Not every codec is equipped to encode 4K video effectively, especially if you want the video to stay as close to high-quality as possible. Challenges also include server strain.

   

Adaptive Bitrate Streaming

Adaptive bitrate streaming (ABR) is a streaming workflow that involves transcoding media files at a wide range of bitrates and selecting which ones to deliver based on viewer-side feedback. Media files are prepared in non-overlapping segments so that as they are delivered to end-user devices, the media server has time to adjust according to viewer-side bandwidth restrictions. In other words, if one segment is lower quality and well below what the viewer’s bandwidth can handle, then another higher quality segment is sent. ABR helps deliver the highest possible quality without causing buffering.

   

Bandwidth

Your bandwidth is the volume of data your network connection can transfer at any given moment. Like video bitrate, it’s measured in bits. For example, if your bandwidth is 8,000 kbps, then it can transfer 8,000 bits a second. In video streaming, if your video is being transferred at too high a bitrate, then you will experience buffering. Bandwidth can fluctuate, making streaming a tricky balance between quality and reliability.

   

Bitrate

Bitrate refers to the amount of data being sent over a connection within a given timeframe. For example, a bitrate of 6,000 kbps is sending 6k kilobits each second. Higher video bitrates lead to faster and, whenever able, higher quality video content. However, bandwidth is also measured in bits (kbps, Mbps, etc.). This defines the amount of data a given network can handle in a set timeframe. If the video bitrate exceeds the bandwidth bitrate, the video will buffer.

   

Buffering

You know it as the spinning wheel that indicates your video isn’t streaming properly. Some people mistakenly assume this means the video itself isn’t high enough quality. However, buffering typically happens when the video is too large (or high-quality) for your network to handle. When the video bitrate exceeds your bandwidth bitrate, buffering occurs.

   

Cloud Transcoding

Cloud transcoding is a form of transcoding using cloud-based software or services and often employed by content delivery networks (CDNs). Companies that opt for cloud-based transcoding can avoid the hassle associated with local server strain when trying to manage their on-prem hardware or software solutions.

   

Codec

Codec is a portmanteau of “compress” and “decompress” and refers to a hardware of software component used to compress digital files for storage and delivery. Codecs and be lossy or lossless, referring to the loss of digital information during the compression process. Codecs can differ in quality and efficiency, making some better suited for video streaming.

   

Compression

Compression is another common term for encoding, referring to how the video codecs compress the files for delivery.

   

Decompression

Decompression is another common term for unencoding video files for the purposes of transcoding or playback.

   

Encoding

Video encoding refers to the process by which raw video files are packaged for delivery across a network. These raw files are way too large to send on their own. They must be compressed using specific codecs. Which codecs you use to encode your video files may depend on the streaming protocol you plan to send them with. For example, the HLS streaming protocol works with H.264 and HEVC/H.265 codecs.

   

Encoding Ladder

Encoding ladders define the spectrum of video bitrates for streaming segments in an ABR workflow. At the top of the encoding ladder, you have the highest bitrates and resolutions for the most capable end user bandwidth and devices. On the bottom, you have the lowest bitrate and resolution combination for those viewer setups that can’t handle as much. The encoding ladder defines these thresholds and provides a framework for how the ABR stream moves up and down.

   

High-Density Transcoding

High-density streaming is when large volumes of video streams are being sent all at once. This is often the case with large-scale live event streaming. High density-transcoding refers to the transcoding portion of this streaming workflow, where high-volumes of streams are being processed and sent out all at once. This is challenging in that it is resource demanding and puts strain on media servers. High-efficiency compression can make it significantly easier.

   

Latency

Latency is the delay between when a stream is sent and when it is received. Live broadcasts like Saturday Night Live are usually not as “live” as advertised. There is a small gap of time (seconds to minutes) between when the content is filmed and when you are watching it on your television. Sometimes this isn’t a big deal, but it can matter a lot in cases where even a few seconds make a huge difference in experience and interactivity. High-density transcoding can help reduce latency in live streams.

   

Live Transcoding

Live transcoding accomplishes the same overall goal as regular transcoding but live. Encoded files are received, transcoded, and delivered to viewers in a steady stream. Naturally, this is necessary for live streams, but live transcoding doesn’t need to be limited to live content. It is also a key function in adaptive bitrate streaming (ABR), which dynamically adjusts streaming bitrate to accommodate end-user bandwidth limitations.

   

Lossless

Lossless encoding is when no consequential information is discarded in order to compress a file. Lossless encoding will involve removing metadata that has no bearing on the content or quality. This ensures the decompressed files are the same quality as the original file. However, it makes compression more challenging.

   

Lossy

Lossy encoding is when digital information is discarded in order to make a file smaller. When it comes to video file compression, this shouldn’t result in lost content. Encoders will discard information they see as “excess”. That said, this lost data could manifest in lower image quality. Additionally, when those files are later decompressed, they won’t be able to regain the lost data. This is an important consideration where video quality is concerned.

   

Multi-Bitrate Streaming

Multi-bitrate streaming (MBR) is similar to ABR in that it involves preparing video files at a range of bitrates for delivery to end user devices. However, it lacks the dynamic functionality of ABR, instead locking a given stream in at a given bitrate once selected. This can be problematic for viewers with fluctuating bandwidth midstream.

   

Packetization

This is another term for transmuxing, which is commonly confused with transcoding. It’s the act of changing the outside of the package as opposed to its contents (i.e. a new file format for delivery).

   

Resolution

Video resolution is defined by the number of pixels in each video frame. Typically, resolution is measured in pixels or pixels per inch (PPI). Video resolution, however, is often measured using an aspect ratio, the most common of which is 16:9. For example, using that ratio, a video might have a resolution of 1280×720. This translates to 1280 pixels wide and 720 pixels high. Transrating is a form of transcoding that specifically alters resolution.

   

Transcoder

Transcoder is the name for the software or hardware used to transcode files. Both hardware and software transcoders have their strengths where speed, quality, and control are concerned.

   

Transcoding

Transcoding is a form of digital alchemy – converting media files (audio or visual) from one form to another. Basically, it takes an encoded media file, unencodes it, and re-encodes it in a new format, typically with a different file size (transize) or bitrate (transrate). In a streaming video workflow, this is done mid-workflow (after first-mile and before last-mile) to prepare files for delivery to a range of devices.

   

Transizing

This subset of transcoding refers specifically to unencoding and re-encoding video files to alter their size.

   

Transmuxing

Transmuxing is not a subset of transcoding because it does not require a video file be unencoded for the purposes of changing it. Transmuxing involves changing the video file container. Not to be confused with the video codec or streaming protocol, the container is the outside package or file format of a video file. It does not require the unencoding the video. Think of it as the wrapping paper on a gift. You need to open the box in order to change the contents of the gift (transcoding). However, you don’t if you just want to change the wrapping paper.

   

Transrating

This subset of transcoding refers specifically to unencoding and re-encoding video files to alter their video bitrate.

   

Variable Bitrate Streaming

Variable Bitrate Streaming (VBR) is an adaptive streaming workflow that combines a bit of ABR and MBR. Like ABR, VBR transcodes video segments into a range of video bitrates. Like MBR, VBR commits viewers to a single stream. However, now the stream varies in bitrate from one segment to another. VBR determines the bitrate for the given segments in a handful of ways but it ultimately comes down to assessing the complexity of each segment, making the process adaptive to video content needs more so than those of viewers.

   

Get Your Questions Answered

If you are over reading through technical jargon and ready to talk to someone who can help you navigate transcoding benefits, best practices, and costs, then reach out to one of our streaming experts today!