Video Codecs

Introduction to comparison[edit]The following characteristics are compared in video codecs comparisons:

Video quality per bitrate (or range of bitrates). Commonly video quality is considered the main characteristic of codec comparisons. Video quality comparisons can be subjective or objective.Performance characteristics such as compression/decompression speed, supported profiles/options, supported resolutions, supported rate control strategies, etc.General software characteristics – for example:ManufacturerSupported OS (Linux, Mac OS, Windows)Version numberDate of releaseType of license (commercial, free, open source)Supported interfaces (VfW, DirectShow, etc.)Price (value for money, volume discounts, etc.)Video quality[edit]The quality the codec can achieve is heavily based on the compression format the codec uses. A codec is not a format, and there may be multiple codecs that implement the same compression specification – for example, MPEG-1 codecs typically do not achieve quality/size ratio comparable to codecs that implement the more modern H.264 specification. But quality/size ratio of output produced by different implementations of the same specification can also vary.

Prior to comparing codec video-quality, it is important to understand that every codec can give a varying degree of quality for a given set of frames within a video sequence. Numerous factors play a role in this variability. First, all codecs have a bitrate control mechanism that is responsible for determining the bitrate and quality on a per-frame basis. A difference between variable bitrate (VBR) and constant bitrate (CBR) creates a trade-off between a consistent quality over all frames, on the one hand, and a more constant bitrate, which is required for some applications, on the other. Second, some codecs differentiate between different types of frames, such as key frames and non-key frames, differing in their importance to overall visual quality and the extent to which they can be compressed. Third, quality depends on prefiltrations, which are included on all present-day codecs. Other factors may also come into play.

For a sufficiently long clip, it is possible to select sequences that have suffered little from the compression, and sequences that have suffered heavily, especially if CBR has been used, whereby the quality between frames can vary highly due to different amounts of compression needed to achieve a constant bitrate. So, in a given long clip, such as a full-length movie, any two codecs may perform quite differently on a particular sequence from the clip, while the codecs may be approximately equal (or the situation reversed) in quality over a wider sequence of frames. Press-releases and amateur forums sometimes select sequences known to favor a particular codec or style of rate-control in reviews[citation needed].

Objective video quality[edit]Main article: video qualityObjective video evaluation techniques are mathematical models that approximate results of subjective quality assessment, but are based on criteria and metrics that can be measured objectively and automatically evaluated by a computer program. Objective methods are classified based on the availability of the original video signal, which is considered to be of high quality (generally not compressed). Therefore, they can be classified as:

Full reference methods (FR), where the whole original video signal is availableReduced reference methods (RR), where only partial information of the original video is available, andNo-reference methods (NR), where the original video is not available at all.The main FR metrics are:

Peak signal-to-noise ratio (PSNR)The most widely used video quality metric during the last 20 years (used approximately in 99% of scientific papers and in 20% of marketing materials). However, the validity of this metric is limited. It is conclusive only when the same codec (or codec type) and content is being compared.[1][2]Structural similarity (SSim.)A new metric (suggested in 2004) that shows better results than PSNR at the cost of a reasonable increase in computational complexity.VQuad-HD an ITU-T J.341 standardThe new standard was recently (Jan 2011) approved by ITU-T as J.341. The new VQuad-HD™ algorithm was developed by Swissqual in 2008–2010. It was the best-performing model in the HDTV competition to find the new standard that was organized by the independent and non-commercial Video Quality Expert Group (VQEG). More information on VQuad-HD can be found in the technical white paper “Video Quality Measurement for High Definition Video Signals,” available for download from: white paperSome other metrics have been suggested by Video Quality Experts Group (VQEG), private companies, and universities, but are not widespread.

The main comparison method is the so-called RD-curve (rate/distortion chart), in which a metric value is plotted against the Y-axis and the bitrate against the X-axis.

Some example NR metrics are:

Blocking measure — measurement power of so-called blocking artefacts (extremely noticeable without deblocking filter usage on low bitrates)Blurring measure — measurement of common video blurring (washout)Subjective video quality[edit]Main article: Subjective video qualityThis is concerned with how video is perceived by a viewer, and designates his or her opinion on a particular video sequence. Subjective video quality tests are quite expensive with regard to time (preparation and running) and human resources.

There is an enormous number of ways of showing video sequences to experts and of recording their opinions. A few of them have been standardized. They are thoroughly described in ITU-R recommendation BT.500.

The following subjective video quality comparison methods are used:

Double Stimulus Impairment Scale (DSIS) — suggested in ITU-R BT.500-11.Double Stimulus Continuous Quality Scale (DSCQS) type I and type II — suggested in ITU-R BT.500-11Stimulus Comparison Adjectival Categorical Judgement (SCACJ) — suggested in ITU-R BT.500-11Subjective Assessment Method for Video Quality evaluation (SAMVIQ)MSU Continuous Quality Evaluation (MSUCQE)The reason for measuring subjective video quality is the same as for measuring the Mean Opinion Score for audio. Opinions of experts can be averaged, and the average mark is usually given with confidence interval. Additional procedures can be used for averaging. For example, experts who give unstable results may be rejected (for instance, if their correlation with average opinion is low).

In case of video codecs, this is a very common situation. When codecs with similar objective results show results with different subjective results, the main reasons can be:

Pre- and postfilters are widely used in codecs. Codecs often use prefilters such as video denoising, deflicking, deshaking, etc. Denoising and deflicking normally maintain PSNR value while increasing visual quality (the best slow denoising filters also increase PSNR on medium and high bitrates). Deshaking greatly decreases PSNR, but increases visual quality. Postfilters show similar characteristics — deblocking and deringing maintain PSNR, but increase quality; graining (suggested in H.264) essentially increases video quality, especially on big plasma screens, but decreases PSNR.Note: All filters increase compression/decompression time, so they enhance visual quality but decrease the speed of coding an decoding.Motion estimation (ME) search strategy can also cause different visual quality for the same PSNR. So-called true motion search commonly will not reach minimum sum of absolute differences (SAD) values in codec ME, but may result in better visual quality. Such methods also require more compression time.Rate control strategy. VBR commonly cause better visual quality marks than CBR for the same average PSNR values for sequences.It is difficult to use long sequences for subjective testing. Commonly, three or four ten-second sequences are used, while full movies are used for objective metrics. Sequence selection is important — those sequences that are similar to the ones used by developers to tune their codecs are more competitive.

Performance comparison[edit]Speed comparison[edit]Main article: Frame rateNumber of frames per second (FPS) commonly used for compression/decompression speed measurement.

The following issues should be considered when estimating probable codec performance differences:

Decompression (sometimes compression) frame time uniformity – Big differences in this value can cause annoyingly jerky playback.SIMD support by processor and codec — E.g., MMX, SSE, SSE2, each of which change CPU performance on some kinds of tasks (often including those with which codecs are concerned).Multi-threading support by processor and codec – Sometimes turning on Hyper-threading support (if available on a particular CPU) causes codec speed to decrease)RAM speed – generally important for most codec implementationsProcessor cache size – low values sometimes cause serious speed degradation, e.g. for CPUs with low cache such as several of the Intel Celeron series.GPU usage by codec — some codecs can drastically increase their performance by taking advantage of GPU resources.So, for example, codec A (being optimized for memory usage – i.e., uses less memory) may, on modern computers (which are typically not memory-limited), give slower performance than codec B. Meanwhile, the same pair of codecs may give opposite results if running on an older computer with reduced memory (or cache) resources.

Profiles support[edit]Main article: H.264Modern standards define a wide range of features and require very substantial software or hardware efforts and resources for their implementation. Only selected profiles of a standard are typically supported in any particular product. (This is very common for H.264 implementations for example.)

The H.264 standard includes the following seven sets of capabilities, which are referred to as profiles, targeting specific classes of applications:

Baseline Profile (BP): Primarily for lower-cost applications with limited computing resources, this profile is used widely in videoconferencing and mobile applications.Main Profile (MP): Originally intended as the mainstream consumer profile for broadcast and storage applications, the importance of this profile faded when the High profile (HiP) was developed for those applications.Extended Profile (XP): Intended as the streaming video profile, this profile has relatively high compression capability and some extra tricks for robustness to data losses and server stream switching.High Profile (HiP): The primary profile for broadcast and disc storage applications, particularly for high-definition television applications. (This is the profile adopted into HD DVD and Blu-ray Disc, for example.)High 10 Profile (Hi10P): Going beyond today’s mainstream consumer product capabilities, this profile builds on top of the High Profile, adding support for up to 10 bits per sample of decoded picture precision.High 4:2:2 Profile (Hi422P): Primarily targeting professional applications that use interlaced video, this profile builds on top of the High 10 Profile, adding support for the 4:2:2 chroma sampling format while using up to 10 bits per sample of decoded picture precision.High 4:4:4 Predictive Profile (Hi444PP): This profile builds on top of the High 4:2:2 Profile, supporting up to 4:4:4 chroma sampling, up to 14 bits per sample, and additionally supporting efficient lossless region coding and the coding of each picture as three separate color planes.Multiview High Profile: This profile supports two or more views using both inter-picture (temporal) and MVC inter-view prediction, but does not support field pictures and macroblock-adaptive frame-field coding.The standard also contains four additional all-Intra profiles, which are defined as simple subsets of other corresponding profiles. These are mostly for professional (e.g., camera and editing system) applications:

High 10 Intra Profile: The High 10 Profile constrained to all-Intra use.High 4:2:2 Intra Profile: The High 4:2:2 Profile constrained to all-Intra use.High 4:4:4 Intra Profile: The High 4:4:4 Profile constrained to all-Intra use.CAVLC 4:4:4 Intra Profile: The High 4:4:4 Profile constrained to all-Intra use and to CAVLC entropy coding (i.e., not supporting CABAC).Moreover, the standard now also contains three Scalable Video Coding profiles.

Scalable Baseline Profile: A scalable extension of the Baseline profile.Scalable High Profile: A scalable extension of the High profile.Scalable High Intra Profile: The Scalable High Profile constrained to all-Intra use.An accurate comparison of codecs must take the profile variations within each codec into account.

See also MPEG-2 Profiles and Levels.

Supported rate control strategies[edit]Main article: Rate distortion theoryVideocodecs rate control strategies can be classified as:

Variable bitrate (VBR) andConstant bitrate (CBR).Variable bitrate (VBR) is a strategy to maximize the visual video quality and minimize the bitrate. On fast-motion scenes, a variable bitrate uses more bits than it does on slow-motion scenes of similar duration, yet achieves a consistent visual quality. For real-time and non-buffered video streaming when the available bandwidth is fixed – e.g. in videoconferencing delivered on channels of fixed bandwidth – a constant bitrate (CBR) must be used.

CBR is commonly used for videoconferences, satellite and cable broadcasting. VBR is commonly used for video CD/DVD creation and video in programs.

Software characteristics[edit]Codecs list[edit]General video codec information — creator/company, license/price, etc.Codec Creator/Maintainer First public release date Latest stable version License Patented compression formats Compression method OpenCL support nVidia CUDA support ATI Stream/AMD APP support Intel AVX support Intel Quick Sync Video supportlibtheora (Theora) 2002-09-25 1.1.1 (2009)[3] BSD-style[4] Patented, but freely licensed[*] lossy Unknown Unknown Unknown Unknown Unknowndirac-research (Dirac) BBC Research Department 2008-09-17 1.0.2 (2009)[5] MPL 1.1, GNU GPL 2, GNU LGPL 2.1 none lossy/lossless Unknown Unknown Unknown Unknown UnknownSchrödinger (Dirac) David Schleef 2008-02-22 1.0.11 (2012)[5] MPL 1.1, GNU GPL 2, GNU LGPL 2, MIT License none lossy/lossless Unknown Yes Unknown Unknown Unknownx264 x264 team 2003 r2525 (2014)[6] GNU GPL MPEG-4 AVC/H.264 lossy/lossless No No No Yes UnknownXvid Xvid team 2001 1.3.3 (2014)[7] GNU GPL MPEG-4 ASP lossy Unknown Unknown Unknown Unknown UnknownFFmpeg (libavcodec) FFmpeg team 2000 2.5 (2014)[8] GNU LGPL MPEG-1, MPEG-2, MPEG-4 ASP, H.261, H.263, VC-3, WMV7, WMV8, MJPEG, MS-MPEG-4v3, DV, Sorenson codec etc. lossy/lossless No No No Yes NoFFavs (libavcodec) FFavs team 2009 0.0.3[9] GNU LGPL MPEG-1, MPEG-2, MPEG-4 ASP etc. lossy/lossless Unknown Unknown Unknown Unknown UnknownBlackbird Forbidden Technologies plc 2006-01 2 Proprietary Blackbird lossy Unknown Unknown Unknown Unknown UnknownDivX DivX, Inc. 2001 DivX Plus (2010)[10] Proprietary MPEG-4 ASP, H.264 lossy Unknown Unknown Unknown Unknown UnknownDivX 😉 a hack of Microsoft’s MPEG-4v3 codec[11][12] 1998 3.20 alpha[13] (2000) Proprietary Microsoft’s MPEG-4v3 (not MPEG-4 compliant) lossy Unknown Unknown Unknown Unknown Unknown3ivx 3ivx Technologies Pty. Ltd. 2001 5.0.5 (2012)[14] Proprietary MPEG-4 ASP lossy Unknown Unknown Unknown Unknown UnknownNero Digital Nero AG 2003 Unknown Proprietary MPEG-4 ASP, H.264[15] lossy Unknown Unknown Unknown Unknown UnknownProRes 422 / ProRes 4444 Apple Inc. 2007 Proprietary Unknown lossy Unknown Unknown Unknown Unknown UnknownSorenson Video Sorenson Media 1998 Proprietary Sorenson Video lossy Unknown Unknown Unknown Unknown UnknownSorenson Spark Sorenson Media 2002 Proprietary Sorenson Spark lossy Unknown Unknown Unknown Unknown UnknownVP3 On2 Technologies 2000 BSD-style[4] Patented, but freely licensed[*] lossy Unknown Unknown Unknown Unknown UnknownVP4 On2 Technologies 2001 Proprietary VP4 lossy Unknown Unknown Unknown Unknown UnknownVP5 On2 Technologies 2002 Proprietary VP5 lossy Unknown Unknown Unknown Unknown UnknownVP6 On2 Technologies 2003 Proprietary VP6 lossy Unknown Unknown Unknown Unknown UnknownVP7 On2 Technologies 2005 Proprietary VP7 lossy Unknown Unknown Unknown Unknown UnknownVP8 On2 Technologies (now owned by Google) 2008 1.1.0 (2012) BSD-style Patented, but freely licensed lossy Unknown Unknown Unknown Unknown UnknownVP9 Google 2013 BSD-style Patented, but freely licensed lossy/lossless Unknown Unknown Unknown Unknown UnknownDNxHD Avid Technology 2004 Proprietary VC-3 lossy Unknown Unknown Unknown Unknown UnknownCinema Craft Encoder SP2 Custom Technology Corporation 2000 (2009)[16] Proprietary MPEG-1, MPEG-2 lossy Unknown Unknown Unknown Unknown UnknownTMPGEnc Free Version Pegasys Inc. 2001 2.525.64.184 (2008)[17] Proprietary MPEG-1, MPEG-2 lossy Unknown Unknown Unknown Unknown UnknownWindows Media Encoder Microsoft 1999 9 (2003) (WMV3 in FourCC) Proprietary WMV, VC-1, (in early versions MPEG-4 Part 2 and not MPEG-4 compliant MPEG-4v3, MPEG-4v2) lossy Unknown Unknown Unknown Unknown UnknownCinepak Created by SuperMac, Inc.Currently maintained by Compression Technologies, Inc.[18]

1991 (1999) Proprietary Unknown lossy Unknown Unknown Unknown Unknown UnknownIndeo Video Intel Corporation, currently offered by Ligos Corporation 1992 5.2 Proprietary Indeo Video lossy Unknown Unknown Unknown Unknown UnknownTrueMotion S The Duck Corporation 1995 Proprietary TrueMotion S lossy Unknown Unknown Unknown Unknown UnknownRealVideo RealNetworks 1997 RealVideo 10[19] Proprietary H.263, RealVideo lossy Unknown Unknown Unknown Unknown UnknownHuffyuv Ben Rudiak-Gould 2000 2.1.1 (2003)[20] GNU GPL 2 none Lossless Unknown Unknown Unknown Unknown UnknownLagarith Ben Greenwood 2004-10-04 1.3.27 (2011-12-08)[21] GNU GPL 2 none Lossless Unknown Unknown Unknown Unknown UnknownMainConcept MainConcept GmbH 1993 8.8.0 (2011) Proprietary MPEG-1, MPEG-2, H.264/AVC, H.263, VC-3, MPEG-4 Part 2, DV, MJPEG etc. lossy Yes[22] Yes[23][24] Unknown Unknown Yes[25]Elecard Elecard 2008 G4 (2010)[26] Proprietary MPEG-1, MPEG-2, MPEG-4, AVC lossy No Yes[26] No Yes[26] Yes[26]Codec Creator/Maintainer First public release date Latest stable version License Patented compression formats Compression method OpenCL support nVidia CUDA support ATI Stream/AMD APP support Intel AVX support Intel Quick Sync Video support

The Xiph.Org Foundation has negotiated an irrevocable free license to Theora and other VP3-derived codecs for everyone, for any purpose.[27]

DivX Plus is also known as DivX 8. The latest stable version for Mac is DivX 7 for Mac.Native operating system support[edit]Note that operating system support does not mean whether video encoded with the codec can be played back on the particular operating system – for example, video encoded with the DivX codec is playable on Unix-like systems using free MPEG-4 ASP decoders (FFmpeg MPEG-4 or Xvid), but the DivX codec (which is a software product) is only available for Windows and Mac OS X.

Encoder Operating System SupportCodec Mac OS X other Unix & Unix-like Windows3ivx Yes Yes YesBlackbird Yes Yes YesCinepak Yes No YesDivX Yes No YesFFmpeg Yes Yes YesRealVideo Yes Yes YesSchrödinger (Dirac) Yes Yes YesSorenson Video 3 Yes No YesTheora Yes Yes Yesx264 Yes Yes YesXvid Yes Yes YesElecard Yes No YesTechnical details[edit]Codec Compression type Basic algorithm Highest supported bitrate Highest supported resolution Variable frame rateBlackbird lossy compression Unknown Unknown 384×288 (PAL), 320×240 (NTSC) YesCinepak lossy compression Vector quantization[28] Unknown Unknown UnknownDirac lossy/lossless compression Wavelet compression Unlimited[29] Unlimited[29] YesSorenson 3 lossy compression Unknown Unknown Unknown UnknownTheora lossy compression Discrete cosine transform 2 Gibit/s 1,048,560×1,048,560[30][31] Via chaining[*]RealVideo lossy compression Discrete cosine transform Unknown Unknown YesElecard lossy compression Unknown Unlimited 16k Yes

Theora streams with different frame rates can be chained in the same file, but each stream has a fixed frame rate.[30]Freely available codecs comparisons[edit]List of freely available comparisons and their content description:

Name of comparison Type of comparison Date(s) of publication List of compared codecs CommentsSeries of Doom9 codec comparisons Series of subjective comparison of popular codecs 200220032005DivX4.12, On2 VP3, XviD 1/25 and WMV8 and DivX5.01, XviD 3/27 and ON2 VP4 — at first versionDirac, Elecard AVC HP, libavcodec MPEG-4, NeroDigital ASP, QuickTime 7, Snow, Theora, VideoSoft H.264 HP, XviD 1.1 beta 2 — in last oneSubjective comparison with convenient visualizationSeries of MSU annual H.264 codecs comparisons Series of objective H.264 codecs comparisons with MPEG-4 ASP reference 20042005 Jan.2005 Dec.2006 Dec.2007 Dec.2009 May2010 Apr.2005 (Jan.): Mpegable AVC, Moonlight H.264, MainConcept H.264, Fraunhofer IIS, Ateme MPEG-4 AVC/H.264, Videosoft H.264, DivX Pro 5.1.1 (Not 264! Used for comparison with H.264 codecs as well tuned codec from previous generation MPEG-4 ASP)2005 (Dec.): DivX 6.0 (MPEG-4 ASP reference), ArcSoft H.264, Ateme H.264, ATI H.264, Elecard H.264, Fraunhofer IIS H.264, VSS H.264, x2642006: DivX 6.2.5 (MPEG-4 ASP reference), MainConcept H.264, Intel H.264, VSS H.264, x264, Apple H.264, (partially), Sorenson H.264 (partially)2007: XviD (MPEG-4 ASP codec), MainConcept H.264, Intel H.264, x264, AMD H.264, Artemis H.2642009: XviD (MPEG-4 ASP codec), Dicas H.264, Elecard H.264, Intel IPP H.264, MainConcept H.264, x2642010: XviD (MPEG-4 ASP codec), DivX H.264, Elecard H.264, Intel MediaSDK AVC/H.264, MainConcept H.264, Microsoft Expression, Encoder, Theora, x264Detailed objective comparisonsSeries of Lossless Video Codecs Comparison Two size and time comparisons of lossless codecs (with lossless checking) 2004 Oct.2007 Mar.2004 (14 codecs): Alpary v2.0, AVIzlib v2.2.3, CamStudio GZIP v1.0, CorePNG v0.8.2, FFV1 ffdshow 08/08/04, GLZW v1.01, HuffYUV v2.1.1, Lagarith v1.0.0.1, LEAD JPEG v1.0.0.1, LOCO v0.2, MindVid v1.0 beta 1, MSUlab beta v0.2.4, MSUlab v0.5.2, PicVideo JPEG v., VBLE beta2007 (16 codecs): Alpary, ArithYuv, AVIzlib, CamStudio GZIP, CorePNG, FastCodec, FFV1, Huffyuv, Lagarith, LOCO, LZO, MSU Lab, PICVideo, Snow, x264, YULSin 2007 — more detailed report with new codecs including first standard H.264 (x264)MSU MPEG-4 codecs comparison Objective comparison of MPEG-4 codecs 2005 Mar.DivX 5.2.1, DivX 4.12, DivX 3.22, MS MPEG-4 3688 v3, XviD 1.0.3, 3ivx D4 4.5.1, OpenDivX 0.3 Different versions of DivX was also compared. The Xvid results may be erroneous, as deblocking was disabled for it while used for DivX.Subjective Comparison of Modern Video Codecs Scientifically accurate subjective comparison using 50 experts and SAMVIQ methodology 2006 Feb.DivX 6.0, Xvid 1.1.0, x264, WMV 9.0 (2 bitrates for every codec) PSNR via VQM via SSIM comparison was also doneMPEG-2 Video Decoders Comparison Objective MPEG-2 Decoders comparison 2006 May.bitcontrol MPEG-2 Video Decoder, DScaler MPEG2 Video Decoder, Elecard MPEG-2 Video Decoder, ffdshow MPEG-4 Video Decoder (libavcodec), InterVideo Video Decoder, Ligos MPEG Video Decoder, MainConcept MPEG Video Decoder, Pinnacle MPEG-2 Decoder Objectly tested (100 times per stream) decoders “crash test” (test on damaged stream — like scratched DVD or satellite samples)Codecs comparison Personal subjective opinion 2003 Nov.3ivx, Avid AVI 2.02, Cinepak, DivX 3.11, DivX 4.12, DivX 5.0.2, DV, Huffyuv, Indeo 3.2, Indeo 4.4, Indeo 5.10, Microsoft MPEG-4 v1, Microsoft MPEG-4 v2, Microsoft RLE, Microsoft Video 1, XviD, 3ivx, Animation, Blackmagic 10-bit, Blackmagic 8-bit, Cinepak, DV, H.261, H.263, Motion-JPEG, MPEG-4 Video, PNG, Sorenson Video, Sorenson Video 3 Sometimes comparison is short (up to one text line per codec)Evaluation of Dirac and Theora Scientific paper 2009 Mar.Dirac, Dirac Pro, Theora I, H.264, Motion JPEG2000 (the tested codecs are from Q2-2008) Quite detailed comparison of software available in Q2-2008; However, a buggy version of ffmpeg2Theora was usedVP8 versus x264 Objective and subjective quality comparison of VP8 and x264 2010 Jun.VP8, x264 VQM, SSIM and PSNR for 19 CIF video clips with bitrates of 100, 200, 500 and 1000 kbit/sSee also[edit]Portal icon Free software portalComparison of media playersList of video players (software)List of codecsOpen source codecs and containersComparison of audio coding formatsComparison of container formatsComparison of video editing softwareNotes and references[edit]Jump up ^ Thomos, N., Boulgouris, N. V., & Strintzis, M. G. (2006, January). Optimized Transmission of JPEG2000 Streams Over Wireless Channels. IEEE Transactions on Image Processing , 15 (1).Jump up ^ Xiangjun, L., & Jianfei, C. ROBUST TRANSMISSION OF JPEG2000 ENCODED IMAGES OVER PACKET LOSS CHANNELS. ICME 2007 (pp. 947–950). School of Computer Engineering, Nanyang Technological University.Jump up ^ Xiph.Org Foundation (2009) Theora development website – news, Retrieved 2009-10-06^ Jump up to: a b FAQ: what is the license for Theora?^ Jump up to: a b Dirac Video Compression, Retrieved on 2009-08-08Jump up ^ x264 – a free h264/avc encoder, Retrieved on 2014-12-28Jump up ^, Retrieved on 2011-05-18Jump up ^, Retrieved on 2014-12-27Jump up ^ FFavs, Retrieved on 2009-08-08Jump up ^ “DivX, Inc.”. DivX, Inc. Retrieved 19 May 2011.Jump up ^ VirtualDub VirtualDub documentation: codecs, Retrieved on 2009-08-08Jump up ^ Video Codecs – Compressed Formats, Retrieved on 2009-08-08Jump up ^ Tom’s Hardware (2001-10-22) A Tough Choice: DivX 3.20a Codec Still Better Than DivX 4.01 Codec, Retrieved on 2009-08-08Jump up ^ 3ivx, Retrieved on 2014-12-27Jump up ^ Nero AG What is Nero Digital, Retrieved on 2009-08-08Jump up ^ Custom Technology Corporation CINEMA CRAFT – Download, Retrieved on 2009-08-11Jump up ^ Pegasys Inc. What Is New, Retrieved on 2009-08-11Jump up ^ Compression Technologies, Inc., current maintainer of CinepakJump up ^ RealNetworks Products – Codecs, Retrieved on 2009-08-07Jump up ^ Huffyuv v2.1.1, Retrieved on 2009-08-09Jump up ^ Lagarith Lossless Video Codec, Retrieved on 2014-03-04Jump up ^ [1]Jump up ^ [2]Jump up ^ [3]Jump up ^ [4]^ Jump up to: a b c d [5]Jump up ^ FAQ: isn’t VP3 a patented technology?Jump up ^ Technical description of the Cinepak codec^ Jump up to: a b Frame rate, resolution, etc. are coded as variable length data.^ Jump up to: a b Theora format specification PDF (827 KB)Jump up ^ Requires about 3 terabytes per uncompressed frame at maximum resolution (pg 37, Theora I Specification. March 7, 2006)External links[edit]MSU Subjective Comparison of Modern Video CodecsITS – Video Quality ResearchEvaluation of Subjective Video Quality of Mobile Devices[show] v t eMultimedia compression and container formats[show] v t eData compression methods[show] v t eData compression softwareCategories: Software comparisonsVideo