Common terms you need to know to compare and evaluate the way video is prepared for sharing from station to station.
ARC – ARC is a digital data compression format used to reduce file sizes, without data loss. Used commonly for archival purposes.
Bitrate – Bitrate is the number of bits (pieces of video data) that a video file stores within a given timeframe of playback. The more bits, or data, per second of video, the higher quality the video will be because there is more information available for a player to display. When encoding video, your choice of bitrate will determine the size of the resulting file and the download speed you will need to play a streaming version of the file.
The bitrate is very important in determining the quality of playback experience. An HDTV video (meaning the video meets the broadcast standard of 1080p, 1080i, or 720p) will require a bitrate of at least 8 mbps to retain a level of quality that is not noticeably worse than the source. An HDTV video encoded at a 1 mbps bitrate will not deliver a high quality result, so it is imperative when evaluating video transfer services that you are aware of bitrate boundaries.
NIMxchange offers the highest bitrate allowances in the industry, ensuring that high definition video can be encoded at the bitrates you need to share a high quality result.
Codec – Codec stands for Coder/Decoder. It is a piece of software that allows you to play (or encode) video files of the format that it is built to recognize. If you receive a video in MPEG-2, for example, you will need a MPEG-2 Codec to either view, or transcode it.
Compression – Compression is the process of removing redundant data in digital video so that the file size is smaller and easier to transport or store. There are two main types of compression, Lossy and Lossless.
How compression works: Imagine a video that contains many frames of the same stationary background and only one moving character, say an interview with a Police Officer in a library. Compression algorithms will recognize that the books in the background stay the same and will write the file in such a way as to describe the background image as essentially “show these same pixels for 30 frames” instead of describing every single pixel for every frame. This is only one way a compression algorithm encodes a video, but illustrates the kind of shortcuts taken to make files more manageable.
Encode – Encoding refers to the process of compressing a video file into another format, usually for the purposes of reducing file size for storage or transport.
Encoders – Encoders are software programs that manipulate digital video into the format of your choice, and are extremely important in that they are the actual implementation of a format standard, and can greatly impact the quality of your end results. In addition to the compression format standard, the encoder will also allow you to determine bitrate and resulting file size.
Generational Loss – Refers to the reduction in quality of a piece of media as it is converted, or transcoded, from one format into another. Like making copies of copies, generational loss increases each time a video file is re-encoded.
Lossless Compression - Describes digital data compression techniques that only remove redundant data in such a way that the file can be returned to its original state in its entirety. No video data is permanently lost due to the encoding process.
Lossy Compression – Describes digital data compression techniques that aggressively remove redundant data to achieve highly efficient file sizes. This process will result in files that cannot be returned to their original state in their entirety. However, very high video quality can still be maintained and the benefits of smaller file sizes generally outweigh intelligent compromises in quality.
Media Agnostic – Refers to NIMxchange’s ability to receive, encode, and deliver video files in any format. Because NIMxchange is built on a system that incorporates all current encoders and codecs, users submit video in the format they have, and can specify the format of the video they wish to receive and download.
Wrapper/Container – A container, or wrapper is a special file type customized to the player that will be decoding it. This player may require specific implementations of specific format standards, or combine multiple format streams (such as audio and video). Often, these file types are encoded such you can’t view them on other players unless the video files are unwrapped with an unwrapper software program.
.MP4 is the official container for the MPEG-4 video format standard, for example. QuickTime is one of the oldest containers in use and uses the .mov file format to combine MPEG-4 AVC video streams with AAC audio.
Compression Format Standards
MPEG-2 – A common video format standard that compresses video to ready it for transport or playback on MPEG-2 ready devices (such as DVD player and Digital TVs). MPEG-2 is popular because it offers quality compression with many options for resolution, framerate, bitrate, and frame type.
H.264/MPEG-4 (AVC) – A recent format standard for video compression that was designed specifically with High Definition video in mind. The standard is known by either H.264 or MPEG-4 Advanced Video Coding (AVC) and, while maintained by different organizations, they are identical in implementation.
VC-1 – A format standard for video compression originally developed by Microsoft. VC-1 is the official format standard for the Xbox 360, and is part of Blu-ray Disc and HD DVD specifications. Because it can handle very high bitrates and resolutions, it has become attractive to video professionals.
MXF – Material Exchange Format – MXF is a non compression-scheme specific file format that allows for the bundling of media, such as audio and video, with metadata such as text.
Transcoding – Refers to the process of taking an already encoded video or video source and encoding it again. This is done when the video needs to be in a different format and the original source video is not available, or it is not efficient to encode again in different formats.
Cross-convert – Refers to the process of changing one type of TV system to another, the most common being from NTSC to PAL or the other way around.
Down-convert – Refers to the process of transcoding a video file from a high-resolution format into a low-resolution, or analog, format. A video encoded for HDTV would need to be down-converted to be delivered to an SDTV display, for example.
Up-convert – Refers to the process of transcoding a video file from a low-resolution format into a high-resolution format. Since the majority of current video content is not yet HDTV formatted, all HDTVs need upconversion at some stage to be able to display the majority of broadcast and video sources. This is more complex than simply making the picture bigger – which would merely make the image blurry and “boxy” – and both software and hardware can be involved in upconversion solutions.