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All art is but imitation of nature.

- Seneca, Epistles


3. 共享資源 Goodies

3.1 Free Reference Guides for Video Production 


3.1 Free Reference Guide for Video Production

3.1.1 Multimedia Freeware 多媒體自由或共享軟件
3.1.2 Multimedia File format 多媒體檔案
3.1.3 Codec and Compression Technology 編碼、解碼及壓縮技術
3.1.4 Home Video Production Process 影音製作程序
3.1.5 Glossary of AV Technology 技術名詞

3.2 Animated Gif Icon

3.1.3 Codec and Compression Technology

Audio codec

An audio codec is a hardware device or a computer program that compresses/ decompresses digital audio data according to a given audio file format or streaming audio format. The term codec is a combination of 'coder-decoder'. The object of a codec algorithm is to represent the high-fidelity audio signal with minimum number of bits while retaining the quality. This can effectively reduce the storage space and the bandwidth required for transmission of the stored audio file. Most codecs are implemented as libraries which interface to one or more multimedia players, such as XMMS, Winamp or Windows Media Player.

In some contexts, the term "audio codec" can refer to a hardware implementation or sound card. When used in this manner, the phrase audio codec refers to the device encoding an analog audio signal.

Video Codec

A video codec is a device or software that enables video compression and/or decompression for digital video. The compression usually employs lossy data compression. Historically, video was stored as an analog signal on magnetic tape. Around the time when the compact disc entered the market as a digital-format replacement for analog audio, it became feasible to also begin storing and using video in digital form, and a variety of such technologies began to emerge.

Audio and video call for customized methods of compression. Engineers and mathematicians have tried a number of solutions for tackling this problem.

There is a complex balance between the video quality, the quantity of the data needed to represent it (also known as the bit rate), the complexity of the encoding and decoding algorithms, robustness to data losses and errors, ease of editing, random access, the state of the art of compression algorithm design, end-to-end delay, and a number of other factors.

For more technical information about the video codec design please refer to the following:


H.261 Used primarily in older videoconferencing and videotelephony products. H.261, developed by the ITU-T, was the first practical digital video compression standard. Essentially all subsequent standard video codec designs are based on it. It included such well-established concepts as YCbCr color representation, the 4:2:0 sampling format, 8-bit sample precision, 16x16 macroblocks, block-wise motion compensation, 8x8 block-wise discrete cosine transformation, zig-zag coefficient scanning, scalar quantization, run+value symbol mapping, and variable-length coding. H.261 supported only progressive scan video.
MPEG-1 Part 2 Used for Video CDs, and also sometimes for online video. If the source video quality is good and the bitrate is high enough, VCD can look slightly better than VHS. To exceed VHS quality, a higher resolution would be necessary. However, to get a fully compliant VCD file, bitrates higher than 1150 kbit/s and resolutions higher than 352 x 288 should not be used. When it comes to compatibility, VCD has the highest compatibility of any digital video/audio system. Very few DVD players do not support VCD, but they all inherently support the MPEG-1 codec. Almost every computer in the world can also play videos using this codec. In terms of technical design, the most significant enhancements in MPEG-1 relative to H.261 were half-pel and bi-predictive motion compensation support. MPEG-1 supports only progressive scan video.
MPEG-2 Part 2  (a common-text standard with H.262) Used on DVD, SVCD, and in most digital video broadcasting and cable distribution systems. When used on a standard DVD, it offers good picture quality and supports widescreen. When used on SVCD, it is not as good as DVD but is certainly better than VCD due to higher resolution and allowed bitrate. Though uncommon, MPEG-1 can also be used on SVCDs, and anywhere else MPEG-2 is allowed, as MPEG-2 decoders are inherently backwards compatible. In terms of technical design, the most significant enhancement in MPEG-2 relative to MPEG-1 was the addition of support for interlaced video. MPEG-2 is now considered an aged codec, but has tremendous market acceptance and a very large installed base.
H.263 Used primarily for videoconferencing, videotelephony, and internet video. H.263 represented a significant step forward in standardized compression capability for progressive scan video. Especially at low bit rates, it could provide a substantial improvement in the bitrate needed to reach a given level of fidelity.
Sorenson Spark A codec that was licensed to Macromedia for use in its Flash Player 6. In the same family as H.263.
MPEG-4 Part 2 An MPEG standard that can be used for internet, broadcast, and on storage media. It offers improved quality relative to MPEG-2 and the first version of H.263. Its major technical features beyond prior codec standards consisted of object-oriented coding features and a variety of other such features not necessarily intended for improvement of ordinary video coding compression capability. It also included some enhancements of compression capability, both by embracing capabilities developed in H.263 and by adding new ones such as quarter-pel motion compensation. Like MPEG-2, it supports both progressive scan and interlaced video.
DivX, Xvid, FFmpeg MPEG-4 and 3ivx Different implementations of MPEG-4 Part 2.
MPEG-4 Part 10 (a technically aligned standard with the ITU-T's H.264 and often also referred to as AVC) This emerging new standard is the current state of the art of ITU-T and MPEG standardized compression technology, and is rapidly gaining adoption into a wide variety of applications. It contains a number of significant advances in compression capability, and it has recently been adopted into a number of company products, including for example the XBOX 360, PlayStation Portable, iPod, iPhone, the Nero Digital product suite, Mac OS X v10.4, as well as HD DVD/Blu-ray Disc.
x264 A GPL-licensed implementation of H.264 encoding standard, x264 is only an encoder.
VP6, VP6-E, VP6-S, VP7 Proprietary high definition video 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.
Sorenson 3 A codec that is popularly used by Apple's QuickTime, basically the ancestor of H.264. Many of the QuickTime movie trailers found on the web use this codec.
Theora Developed by the Foundation as part of their Ogg project, 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.
WMV (Windows Media Video) Microsoft's family of video codec designs including WMV 7, WMV 8, and WMV 9. It can do anything from low resolution video for dial up internet users to HDTV. The latest generation of WMV is standardized by SMPTE as the VC-1 standard.
VC-1 SMPTE standardized video compression standard (SMPTE 421M). Based on Microsoft's WMV9 video codec. One of the 3 mandatory video codecs in both HD DVD and Blu-Ray high-definition optical disc standards. Commonly found in portable devices and on streaming video websites in its Windows Media Video implementation.
RealVideo Developed by RealNetworks. A popular 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
Huffyuv Huffyuv (or HuffYUV) is a very fast, lossless Win32 video codec written by Ben Rudiak-Gould and published under the terms of the GPL as free software, meant to replace uncompressed YCbCr as a video capture format. See Lagarith as a more up-to-date codec.
Lagarith A more up-to-date fork of Huffyuv is available as Lagarith.
SheerVideo A family of ultrafast lossless QuickTime and AVI codecs, developed by BitJazz Inc., for RGB[A], Y'CbCr[A] 4:4:4[:4], Y'CbCr[A] and 4:2:2[:4] formats; for both 10-bit and 8-bit channels; for both progressive and interlaced data; for both Mac and Windows.
Mobiclip a codec created by Actimagine, maximising mobile phone battery life when playing full length films on a smart-phone handset.

Data compression methods

(Source: Wikipedia;

Video File Format Comparision

640x480² 640x480² 320x240² 720x480
Sorenson, Cinepak, MPEG4 ...
Video bitrate
MP1, MP2, AC3, DTS, PCM MP1, MP2, AC3, DTS, PCM MP3, WMA, OGG, AAC, AC3 QDesign Music, MP3 ... RM DV
Audio bitrate
Min/74min CD
10-20min ~4min
60-180min 30-180
7-18hrs 3-18hrs 14-35hrs 20min
13-30hrs 6-30hrs 25-65hrs 37min
DVD Player Compatibility
Great Good Excellent None Few None None None
Computer CPU Usage
Low High Very High Super high Very High High Low High
Good Great* Excellent* Superb* Great* Great* Decent* Excellent
kbps = thousand bits per second
Mbps = million bits per second
² approximately resolution, it can be higher or lower
~ approximately bitrate, it can be higher or lower
ª DVD with lower video quality, similiar to VCD/SVCD video quality
* the video quality depends on the bitrate and the video resolution, higher bitrate and higher resolution generally means better video quality but bigger file size

Credit 鳴謝

Credit and thanks are hereby granted to all those vendors, their colleagues and collaborating voluntary programmers who contribute their works to the general public for free.


Our Belief in Sharing

After releasing our stock photos for public sharing for more than 1 year, we consolidate our belief in our move to embrace free licence. Last year we released our calendar under creative common licence but we decided to releasae our works under our own free licence for some considerations. Now it's time for us to tell the public our thinking.

Someone claim that the majority of people may enjoy wealth generated from their creative work. So our legislators  have drafted and passed a series of law for the protection of intellectual property. However, under the copyright ordinance, we cannot be sure if a piece of work is allowed to be copied, shared, distributed, reproduced or modified without a complete knowledge about the details of license even though we are willing to pay for the use of it. For the peace of mind, we must create everything from the very beginning together with a thorough prior art search confirming that there is no similar wrok in the world.  However, the new ordinances have not helped too much in protecting our creative works. Customers, including government departments, are expecting "free  demo design service" early  in the stage of tendering quotation for jobs involving the elements of creation.    

The problem is not limited to this. Nobody is able to tell if his idea would coinside with someone living and working in elsewhere of the world. This intrinsic defect of the so-called intellectual property have given rise to the overwhelming rent seeking activities of a group of professional litigators who take advantages from champerty and maintenance. These brave new ordinances, to some extent, have legalized their legal extortion from innocent people. In Hong Kong, their victims are mainly SMEs, especially small retailers or service providers. It's hard for outsiders to imagine how and why a lawful and well disciplined retailer keep receiveing legal letters from prominent law firms representing prominent content providers or trademark owners claiming hundred thousands dollars for the infringement of copyright just for selling stationery of dollars and cents only because it  is deemed by these smart heads to be "too similar" to what they possess. In Western countries, even the wealthy gigantic corporates are their targets. 

Then some people stood up and vowed that this "permission culture" was not the thing they want but that they valued the joy of sharing and recognition of their idea more than money. They realize that whether  or not a piece of work can generate profit relies on the popularity but not the promise of law. In software industry, some vendors introduce the idea of "SAAS" (software as a service) and support the open source movement. In creative industry, some artists start to release their work free of charge to the public for gaining the  popularity and make their money from the provision of service. Thus a number of free license like "creative common", "copyleft", "wiki-common" or "GPL" were created to get around the restriction of copyright which is granted to the creator automatically as a natural right by most of the prevailing legal systems in our world. To the astonishment of a lot of ordinary people, in just a few years, more and more authors have joined the camp of "free culture" and released their work under various kinds of free license.  They contribute their effort in building a more beautiful world. 

However, do not confuss piracy with "free culture".  Advocates of free culture only share with others their own creation but not pirated property from others. Actually, they respect the right of the author of all intellectual property. Whether or not to release their work under free license remain their own choice. 

This point is important when using our hyper-links to these 3rd party web site providing free resources to artists all over the world. We respect the will and the right of the author of all intellectual properties. When we provide the information and hyper-link of these web-sites, we believe that their activities and content are lawful and ethical. Hence, before you visit those webs, please read our disclaimer once again. If you find any abuse or obsession, please email to "".

Taking the most pragmatic point of view, the action of releasing free works to the public may be regarded as a "free demo service" like what a contractor provides in  tendering a quotation for a project. Nevertheless, as a humble person, we should believe in the pure intention of some people who only demand for  echo in return for what they have shared with  the world.

- 11/12/2008