This glossary is for anyone who watches video or listens to audio online, whatever the device. The definitions favor practical use: what the term means for you, in front of your screen.
A
AAC (Advanced Audio Coding): audio codec that succeeds MP3, offering better quality at equal bitrate. It is the most common sound format in video streams and many web radios.
AC3 (Dolby Digital): multichannel audio format, often 5.1, very common on films and some channels. Not every device decodes it; failing that, it can be passed as is to a compatible amplifier.
Adaptive bitrate (ABR): mechanism by which the player constantly chooses the quality according to the available speed. Resolution drops when the network weakens, instead of playback stopping.
API: interface that lets software query a server in a structured way. The Xtream Codes API, for example, returns the list of categories, channels and films as data that the player formats.
AV1: recent, royalty-free video codec, more efficient than HEVC. Hardware decoding is only present on fairly recent devices.
B
Bandwidth: maximum amount of data a connection can carry per second. It must be clearly above the bitrate of the stream you watch to avoid drops.
Bitrate: amount of data used per second of video or audio, expressed in kb/s or Mb/s. With the same codec, a higher bitrate gives better quality, at the cost of higher consumption.
BOM (Byte Order Mark): a few invisible bytes placed at the start of some UTF-8 text files. They can stop a player from recognizing the #EXTM3U line of a playlist.
Bufferbloat: excessive rise in latency when the connection is saturated, caused by queues that are too long in the router. It causes drops even with good theoretical speed.
Buffering: phase during which the player accumulates data before playing or resuming playback. Repeated pauses show that data is not arriving fast enough; see our guide on buffering.
Burned-in subtitles: subtitles built into the picture, impossible to turn off or move, as opposed to subtitles supplied in a separate track.
C
Cache: reserve of data held temporarily by a player or an app. Increasing the playback cache absorbs network variations better, but delays the start and widens the gap behind live.
Catch-up: the ability to watch a program that has already aired, directly from the program guide, when the service records it and has the rights.
CDN (Content Delivery Network): network of geographically spread servers that delivers streams as close as possible to viewers, to reduce latency and spread the load.
Codec: algorithm that compresses (encoding) then decompresses (decoding) video or audio. H.264, HEVC and AV1 are video codecs; AAC and MP3, audio codecs.
Concurrent connections: number of devices allowed to play the same account at the same time. Beyond that, the server refuses the extra connection or cuts the oldest one.
Container: file format that bundles the video, audio tracks and subtitles, such as MP4, MKV or MPEG-TS. The container does not determine quality: the codec does.
D
DASH (MPEG-DASH): standardized adaptive streaming protocol, close to HLS, widely used by video-on-demand platforms. It also cuts the video into segments described by a manifest, in XML format.
DNS: service that translates a domain name into an IP address. A slow or faulty DNS delays the opening of channels and pages.
DRM: set of protection techniques that encrypt content and control its playback. Commercial platforms use it to enforce their broadcast rights.
DTT (digital terrestrial television, TNT in France): digital TV received through a rooftop antenna. In France, its national channels are free.
E
E-AC3 (Dolby Digital Plus): improved, more efficient version of AC3, used in streaming and to carry Dolby Atmos.
EPG (Electronic Program Guide): electronic program guide, which shows the current show and the following ones for each channel. See our page on the EPG guide.
Ethernet: connection by network cable between a device and the router. More stable than Wi-Fi, it is the reference solution for a TV or living-room box.
#EXTINF: line of an M3U playlist that describes the next entry: duration, attributes such as the logo or group, then the displayed name after the comma.
#EXTM3U: mandatory header on the first line of an extended M3U playlist. It can carry global attributes such as url-tvg.
F
FAST (Free Ad-supported Streaming TV): free linear channels broadcast only online and funded by advertising, often built into smart TVs.
FPS (frames per second): number of frames displayed each second. Sport is often broadcast at 50 frames per second in Europe, for smoother motion.
G
group-title: attribute of an #EXTINF line that files the entry in a category, such as "News" or "Documentaries".
H
H.264 (AVC): the most widespread video codec, decoded by almost every device, even old ones. Less efficient than its successors, it remains the safe choice for compatibility.
Hardware acceleration: decoding of the video by a specialized circuit of the graphics processor rather than by the main processor. It reduces power use, heat and stutter, provided the codec is supported by the chip.
HDR (High Dynamic Range): extended dynamic range picture, with brighter whites and more detailed blacks. It requires a compatible screen and 10-bit encoded video.
HEVC (H.265): successor to H.264, about twice as efficient at comparable quality. It is common in 4K, but its hardware decoding depends on the device.
HLS (HTTP Live Streaming): protocol that cuts the video into segments of a few seconds listed in a .m3u8 manifest. It is the most compatible streaming format.
I–J
Icecast / Shoutcast: continuous audio broadcast server software, used by the great majority of web radios.
IPTV (Internet Protocol Television): television carried over the IP protocol. The TV service of operator boxes is the most widespread form of legal IPTV; see Legal or illegal IPTV.
Jitter: variation in the arrival delay of data packets. High jitter forces the player to build a larger reserve to avoid jerks.
L
Latency: time a data packet takes to make the round trip between your device and a server, measured in milliseconds by the ping. In video, latency also means the delay between the real live event and the picture shown.
libmpv: library of the free mpv player, which can play almost all video and audio formats. It is the playback engine of AICKO IPTV.
Live: real-time broadcast of a channel or an event, as opposed to video on demand.
M
M3U: plain-text playlist format, which lists stream addresses with descriptive information. How it works is explained in our article on the M3U format.
M3U8: variant of M3U encoded in UTF-8. The extension also designates HLS manifests, which often causes confusion.
Manifest: small file that describes a segmented stream: list of segments, available qualities, audio tracks and subtitles.
MKV (Matroska): open, very flexible container, able to bring several audio tracks and subtitles together in a single file.
MPEG-TS: container designed for continuous broadcast, used by digital television and many live streams, recognizable by the .ts extension.
Multicast: sending the same stream, just once, to all the subscribers watching it. Operators use it for their television, which saves enormous network capacity.
P
Audio passthrough: transmission of compressed sound, without decoding, to an amplifier or soundbar that takes care of decoding it. Essential for enjoying multichannel sound on external equipment.
Packet loss: data that never reaches its destination. Even a small percentage of loss is enough to cause picture artifacts or drops.
Ping: measurement of the round-trip time to a server. A stable, low ping indicates a healthy connection.
player_api.php: entry point of the Xtream Codes API, which players query with the username and password to obtain categories and streams.
Playlist: ordered list of streams or files to play. In IPTV, the term most often means an M3U file.
Powerline (CPL): technique that carries the computer network through electrical outlets. Handy for connecting a TV far from the router, with very variable performance depending on the installation.
R
Replay: catch-up TV offered by channels, for a period that depends on the rights of each program.
Resolution: number of pixels in the picture: 720p (HD), 1080p (Full HD), 2160p (4K). A high resolution is only worthwhile if the bitrate keeps up.
S
Segment: small chunk of video of a few seconds, downloaded one after another in the HLS and DASH protocols.
Software decoding: decoding of the video by the main processor, without the help of a dedicated circuit. More universal, it is also more demanding and can make a modest device heat up or stutter.
SRT: the simplest and most common subtitle format: a text file with numbers, timestamps and the text to display.
Streaming: playing content as it is downloaded, without waiting for the end of the transfer.
T
tvg-id: identifier of a channel in an M3U playlist, which must match exactly the identifier of the same channel in the program guide file.
tvg-logo: attribute that gives the address of the image displayed as a channel's or radio's logo.
tvg-shift: attribute of an #EXTINF line that shifts a channel's guide by a number of hours, to correct a time offset.
U
URL: full address of a resource on the Internet, such as the address of a stream or a playlist. In an Xtream URL, the username and password often appear in clear text: it must not be shared.
url-tvg: attribute of the #EXTM3U line that gives the address of the program guide to associate with the playlist.
UTF-8: universal character encoding, which lets accents and all alphabets display correctly. It is the encoding to use for a playlist.
V
VOD (video on demand): films and series that you start at the moment of your choice, as opposed to live.
W
WebVTT: subtitle format designed for the web, close to SRT, which also accepts position and style cues. It is often found in HLS streams.
Widevine: content protection system used on Android and many TVs. Level L1 allows high definition on commercial platforms, level L3 often limits it to standard definition.
Wi-Fi 5 / Wi-Fi 6: generations of wireless networks. Wi-Fi 6 copes better with many devices connected at once; the 5 GHz band is faster, the 2.4 GHz band carries farther.
X
Xtream Codes: name of a very widespread connection interface, based on a server address, a username and a password. See our page on Xtream and M3U formats.
XMLTV: program guide file format, which describes the channels (<channel>) and the shows (<programme>) with their times and time zones.
Summary
- The codec determines quality; the container is just the packaging.
- HLS, DASH and MPEG-TS are the main ways streams are carried.
- An M3U playlist and an Xtream Codes account are only ways to reach streams, legal or not depending on their source.
- Latency, jitter and packet loss explain most drops, more than speed alone.
Frequently asked questions
What is the difference between a codec and a container?
The codec compresses the picture or sound; the container gathers the compressed tracks in a file or stream. An MKV file can hold H.264 video as well as HEVC: it is the codec that decides whether your device can play it.
Are M3U and M3U8 the same thing?
Almost. M3U8 is an M3U encoded in UTF-8. But the .m3u8 extension is also used for HLS manifests, which describe the segments of a single stream rather than a list of channels.
Why do we talk about latency for live video?
The term covers both the network's response time, measured by ping, and the delay between the real event and the picture shown, due to encoding, segmentation and the player's buffer.
Does IPTV necessarily mean an illegal offer?
No. IPTV is a technique for carrying television over the Internet, used notably by operator boxes. Only the lack of rights to the programs makes an offer unlawful.
