<aside> đź’ˇ List of terms often used in articles, blog posts and documentation
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Lossy codec designed to be the successor of the MP3 format, AAC generally achieves higher sound quality than MP3 at the same bit rate. Can contain up to 48 channels. The quality for stereo is satisfactory to modest requirements at 96 kbit/s in joint stereo mode.
Lossy codec based on the MDCT algorithm, which can contain up to 6 audio channels at max 640 kbps per channel. Also supports mono and stereo modes and sample rate up to 48 kHz.
Subtitle format that allows for more advanced subtitles than the conventional SRT and similar formats. Commonly used with anime.
Surround / 3D sound format where the feeling of room filling sound can be achieved with any number of speakers (2, 5.1, 7.1).
A video bitrate is the number of bits that are processed in a unit of time. Higher bitrate equals higher quality but might need transcoding or fast network equipment to get the stream to the client
If a subtitle stream is selected and is not compatible with the Plex App, then the Server will embed (“burn in”) the subtitle text within the video. This requires a full transcode of the video stream.
The bitrate in the stream is delivered at a single speed (e.g 320kbps) for the whole duration of playback. Ensures that the quality of the media streamed is consistent, but at a slightly higher filesize.
The device that will be used to view the media on. This can be a TV, set-top box, gaming console, mobile phone, KODI, ...
Takes data and either compresses it (for transport and storage) or decompresses it (for viewing or transcoding).
Black box which includes the compressed video and audio, as well as the information needed by the rendering device's data format, so the actual video and audio can be decoded by the target hardware.
Lossy audio codec related to aptX based on the ADPCM algorithm. Can achieve louder sound than AC3 or AAC
When the media is 100% compatible with the client: container, bitrate, codecs and resolution are all compatible. When a media item is Direct Played on an App, the file is sent directly to the device without being changed.
When the audio and video is in a compatible codec but in an incompatible container it will be Direct Streamed. Audio and video are copied from the original container, saved in compatible container and Plex packages the content on-the-fly before streaming it. Direct Streaming a file uses very little processing power without any loss in video quality.
Successor to DCA, lossless audio codec that supports sample rates of max 192 kHz for 6 channels and 96 kHz for 8 channels, capable of virtually any number of discrete channels but is limited by storage media. Supports variable bit rates up to 24.5 Mbit/s. When played back on devices which do not support the Master Audio or High Resolution extension, it degrades to a "core" track which is lossy
Successor to AC3, that supports 15 channels at max 6.144 Mbps per channel.
Offers robust image quality at relatively low bit rates and high compression ratios. It's very scalable, so you can also have high-bit-rate H.264 video that looks fabulous. This is what's typically used for Blu-ray playback.
High Efficiency Video Codec: Offers the same advantages as H264 but at a higher compression rate.
See Transcoding. Uses a graphics processing unit (GPU) to perform transcoding. This offloads the processing from the CPU. A discrete or integrated graphics card can be used.
Used for those people in the home so that communal Plex apps can quickly switch between users. Can be someone with their own or a managed user by the server admin. A Plex Pass feature.
Compression method that does not sacrifice any data or quality, but at higher file sizes.
Compression method that sacrifices some data/quality to achieve a smaller file size.
Free, open container format, that can hold an unlimited number of video, audio, picture or subtitle tracks in one file.
Video inside MP4 files are encoded with H.264, while audio is usually encoded with AAC, but other audio standards can also be used.
Audio decoding is done in software and passed through in PCM streams to the receiver which outputs it to speakers.
Subtitle format consisting of a timed sequence of images. Other formats like ASS or SRT are plain text format with timecodes. PGS is not compatible with all devices and transcoding PGS requires burning in.
Premium features that help maintain the development of Plex. See https://www.plex.tv/plex-pass/#modal-features for feature set.
Human-readable subtitle format where the subtitles are stored sequentially along with the timing information.
When a client is incompatible with the media (e.g incompatible codec or container), Plex will transcode the media and convert it to a compatible format for the client device. Because transcoding enforces an extra step to get the media streamed to the client it will always be slower than Direct Playing/Streaming and might require high amount of processing power. Certain CPUs carry optimisations for transcoding like QuickSync
Lossless audio codec and successor to AC3. Uses MLP as algorithm. Can carry up to 16 audio channels, sample rates up to 192 kHz. VBR codec which can also contain metadata for the stream (normalization etc.)
The stream is not delivered in a single bitrate (e.g 320kbps for the complete duration of playback) but the bitrate is going to fluctuate during playback. It still has a max bitrate but might drop to a lower bitrate. Does not guarantee the media quality streamed to be consistent but is smaller in file size.