Video Coding Standards

Video coding containers and standards

Gemma Milla

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Table of contents

1.  Introduction

2.  Video containers

2.1. The container concept

2.2. Example

2.3. List of most common containers

3. Video codecs

3.1. Video coding standards organizations

3.2. Most common codecs and formats

4. Bibliography

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1. Introduction

�  To codify a video is the process of transforming an analog video signal to a digital one. Most of the video coders compress the information so that it can be stored or transmitted while occupying as little space as possible.

�  A video codec (short word for coder/ decoder) is a devise or software that enables compression or decompression of digital video.

�  It’s important to emphasize the fact that the compression algorithm used entail a data loss.

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2.1. The container concept

�  A container or wrapper format is a type of file format that contains various types of data compressed by different standardized codecs. In other words, container formats are wrappers in which they don’t specify which codec is used, but rather it defines how the video (or audio and other data) is stored within the container.

How do they work together? Think of the container as the file itself. Think of the codec as its contents. The important thing to realice is that some containers (specially the good ones) can hold many codecs. For instance, a .MOV container can hold almost any kind of codec data. The same goes for MP4 and .AVI files which can hold a wide variety of codecs as their contents. �  The container doesn’t decide the quality or features of the video itself, that’s

up to the codec. 4

2.2. Exemple

To understand the difference between a container, a compression scheme, and a codec, first we need to break down the parts of a video file. Think of a video file as a bookshelf filled with books.

Multimedia Container: The Bookshelf The multimedia container is like the bookshelf in that it can hold many tracks of audio and video just like a bookshelf can hold many books. Common container formats include MOV, MXF, and AVI.

Compression Scheme: The Language of the Book Inside of each audio and video track, the information is represented in the language of the compression scheme. Common compression schemes include H.264, MPEG4 part 2, ProRes, DNxHD, and so on.

Codec : The Author of the Book A codec (encoder/decoder) is a piece of hardware or software that interprets an audio or video signal and compresses it. Each compression scheme can be implemented in different ways which creates different codecs for the same compression scheme.

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2.3. List of most common containers

•  3GP (used by many mobile phones; based on the ISO base media file format) •  ASF (container for Microsoft WMA and WMV, which today usually do not use a

container) •  AVI (the standard Microsoft Windows container, also based on RIFF) •  DVR-MS ("Microsoft Digital Video Recording", proprietary video container format

developed by Microsoft based on ASF) •  Flash Video (FLV, F4V) (container for video and audio from Adobe Systems) •  IFF (first platform-independent container format) •  Matroska (MKV) (not limited to any codec or system, as it can hold virtually

anything. It is an open standard and open source container format) •  MJ2 - Motion JPEG 2000 file format, based on the ISO base media file format

which is defined in MPEG-4 Part 12 and JPEG 2000 Part 12 7

•  QuickTime File Format (standard QuickTime video container from Apple Inc.)

•  MPEG program stream (standard container for MPEG-1 and MPEG-2 elementary streams on reasonably reliable media such as disks; used also on DVD-Video discs)

•  MPEG-2 transport stream (a.k.a. MPEG-TS) (standard container for digital broadcasting and for transportation over unreliable media; used also on Blu-ray Disc video; typically contains multiple video and audio streams, and an electronic program guide)

•  MP4 (standard audio and video container for the MPEG-4 multimedia portfolio, based on the ISO base media file format defined in MPEG-4 Part 12 and JPEG 2000 Part 12) which in turn was based on the QuickTime file format

•  Ogg (standard container for Xiph.org audio format Vorbis and video format Theora)

•  RM (RealMedia; standard container for RealVideo and RealAudio)

•  There are many other container formats, such as NUT, MXF, GXF, ratDVD, SVI, VOB and DivX Media Format.

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3.1. Video coding organizations

Two organizations dominate video compression standardization:

�  ITU-T Video Coding Experts Group (VCEG)

International Telecommunications Union – Telecommunications Standardization Sector (ITU-T, a United Nations Organization, formerly CCITT)

�  ISO/IEC Moving Picture Experts Group (MPEG)

International Standardization Organization and International Electrotechnical

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Chronological progression of ITU and MPEG standards

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3.2. Most common codecs and formats

Ø  H.265/ MPEG-H HEVC codecs •  x265: A GPL-licensed implementation of the H.265 video standard. x265 is only an

encoder. Ø  H.264/ MPEG-4 AVC codecs

•  x264: A GPL-licensed implementation of the H.264 video standard. x264 is only an encoder. •  Nero Digital: Commercial MPEG-4 ASP and AVC codecs developed by Nero AG. •  QuickTime H.264: H.264 implementation released by Apple. •  DivX Pro Codec: An H.264 decoder and encoder was added in version 7.

Ø  H.263/ MPEG-4 Part 2 codecs •  DivX Pro Codec: A proprietary MPEG-4 ASP codec made by DivX, Inc. •  Xvid: Free/open-source implementation of MPEG-4 ASP, originally based on the OpenDivX

project. •  FFmpeg MPEG-4: Included in the open-source libavcodec codec library, which is used by default

for decoding or encoding in many open-source video players, frameworks, editors and encoding tools such as MPlayer, VLC, ffdshow or GStreamer. Compatible with other standard MPEG-4 codecs like Xvid or DivX Pro Codec.

•  3ivx: A commercial MPEG-4 codec created by 3ivx Technologies. Ø  H.262/ MPEG-2 codecs

•  x262: A GPL-licensed implementation of the H.262 video standard. x262 is only an encoder. 11

Ø  Microsoft codecs

•  WMV (Windows Media Video): Microsoft's family of proprietary video codec designs including WMV 7, WMV 8, and WMV 9. The latest generation of WMV is standardized by SMPTE as the VC-1 standard.

•  MS MPEG-4v3: A proprietary and not MPEG-4 compliant video codec created by Microsoft. Released as a part of Windows Media Tools 4. A hacked version of Microsoft's MPEG-4v3 codec became known as DivX.

Ø  Google (On2) codecs

•  VP6, VP6-E, VP6-S, VP7, VP8 VP9: Proprietary high definition video compression formats and codecs developed by On2 Technologies used in platforms such as Adobe Flash Player 8 and above, Adobe Flash Lite, Java FX and other mobile and desktop video platforms. Supports resolution up to 720p and 1080p. VP8 has been made open source by Google under the name libvpx or VP8 codec library.

•  libtheora: A reference implementation of the Theora video compression format developed by the Xiph.org Foundation, based upon On2 Technologies' VP3 codec, and christened by On2 as the successor in VP3's lineage. Theora is targeted at competing with MPEG-4 video and similar lower-bitrate video compression schemes.

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Ø  Other codecs

•  Schrödinger and dirac-research: implementations of the Dirac compression format developed by BBC Research at the BBC. Dirac provides video compression from web video up to ultra HD and beyond.

•  DNxHD codec: a lossy high-definition video production codec developed by Avid Technology. It is an implementation of VC-3.

•  Sorenson 3: A video compression format and codec that is popularly used by Apple's QuickTime, sharing many features with H.264. Many movie trailers found on the web use this compression format.

•  Sorenson Spark: A codec and compression format that was licensed to Macromedia for use in its Flash Video starting with Flash Player 6. It is considered as an incomplete implementation of the H.263 standard.

•  RealVideo: Developed by RealNetworks. A popular compression format and codec technology a few years ago, now fading in importance for a variety of reasons.

•  Cinepak: A very early codec used by Apple's QuickTime.

•  Indeo, an older video compression format and codec initially developed by Intel.

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4. Bibliography

�  Websites consulted:

https://library.rice.edu

http://www.pitivi.org/manual/codecscontainers.html

http://www.fallenempiredigital.com/

http://www.eetimes.com

https://www.wikipedia.org

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