CODEC’s and Video Formats
Very often one encounter with problem with audio, video or movie files (especially those downloaded from internet) that, “CODEC Missing or Rendering Decoder unavailable.” Even some or the other times, we have observed that the movie’s downloaded through torrent carry a suffix Divx or XviD, All these suffix are nothing but a CODEC.
In this article I’m going to discuss the codec’s, how to correct the missing codec problem and some basics about Video formats.
CODEC – What is that?
According to Samsung – Codec is a any type of format used to compress the file to smaller size. But I think the right definition of CODEC is A codec is a device or program capable of encoding and/or decoding a digital data stream or signal. The word codec may be a combination of any of the following: 'compressor-decompressor', 'coder-decoder', or 'compression/decompression algorithm'.
In the mid 20th century, a "codec" was hardware that coded analog signals into Pulse-code modulation (PCM) and decoded them back. Late in the century the name came to be applied to a class of software for converting among digital signal formats, and including compander functions.
In the recent, software sense, codecs encode a data stream or signal for transmission, storage or encryption, or decode it for viewing or editing. Codecs are often used in videoconferencing and streaming media applications. A video camera's analogue-to-digital converter (ADC) converts its analogue signals into digital signals, which are then passed through a video compressor for digital transmission or storage. A receiving device then runs the signal through a video decompressor, then a digital-to-analogue converter (DAC) for analogue display. A "codec" is a generic name for a video conferencing unit.
An audio compressor converts analogue audio signals into digital signals for transmission or storage. A receiving device then converts the digital signals back to analogue using an audio decompressor, for playback. An example of this are the codecs used in the sound cards of personal computers. Visit http://www.dbpoweramp.com/ for details.
The raw encoded form of audio and video data is often called essence, to distinguish it from the metadata information that together make up the information content of the stream and any "wrapper" data that is then added to aid access to or improve the robustness of the stream.
Color Encoding format for Television Broadcasting
(Image taken from Wikipedia)
There are three main standards in use around the world, PAL (Phase Alternating Line), NTSC (National Television System Committee) and SECAM (Séquentiel Couleur à Mémoire—Sequential Color with Memory).
The system used in North America is NTSC. Western Europe, Australia, and Eastern South America use PAL. Eastern Europe used SECAM, but switched to PAL after the change of the political regimes there. France still uses SECAM. Generally, a device (such as a television) can only read or display video encoded to a standard which the device is designed to support; otherwise, the source must be converted (such as when European programs are broadcast in North America or vice versa).
NTSC
NTSC is the analog television system in use in the United States, Canada, Japan, Mexico, the Philippines, South Korea, Taiwan, and some other countries (see map). It is named for the National Television System Committee. The first black-and-white NTSC standard for broadcast was developed prior to the Second World War and had no provision for color transmissions. The standard called for 525 lines of picture information in each frame, and 30 frames per second; the frame rate was later slightly adjusted for the color standard. Civilian development of commercial television was halted with the entry of the United States into the war. In 1953 a second standard was issued, which allowed color broadcasting to be compatible with the existing stock of black-and-white receivers, while maintaining the broadcast channel bandwidth already in use. This was an important commercial advantage over incompatible color systems that had also been proposed. NTSC was the first widely adopted broadcast color system. After over a half-century of use, over-the-air NTSC transmissions will be replaced with ATSC in the United States in 2009.
NTSC color encoding is used with the M format (see broadcast television systems), which consists of 30/100.1% (or approximately 29.97) interlaced frames of video per second. Each frame consists of a total of 525 scanlines, of which 486 make up the visible raster. The NTSC field refresh frequency was originally exactly 60 Hz in the black-and-white system, chosen because it matched the nominal 60 Hz frequency of alternating current power used in the United States. In the color system the refresh frequency was shifted slightly downward to 59.94 Hz to eliminate stationary dot patterns in the color carrier.
PAL
PAL, short for Phase Alternating Line, is a color encoding system used in broadcast television systems in large parts of the world. Other common analog television systems are SECAM and NTSC. This page discusses the colour encoding system only.
PAL vs. NTSC
NTSC receivers have a tint control to perform colour correction manually. If this isn't adjusted correctly, the colours will be faulty. The PAL standard automatically removes hue errors by utilizing phase alternation of the colour signal (see technical details), so a tint control is unnecessary. Chrominance phase errors in the PAL system are cancelled out using a 1H delay line resulting lower saturation, which is much less noticeable to the eye than NTSC hue errors.
Refer the table for details
SECAM
SECAM, also written SÉCAM (Séquentiel couleur avec mémoire, French for "Sequential Color with Memory"), is an analog color television system first used in France. A team led by Henri de France working at Compagnie Française de Télévision (later bought by Thomson) invented SECAM. It is, historically, the first European color television standard.
Just as the other color standards adopted for broadcast usage over the world, SECAM is a compatible standard, which means that monochrome television receivers predating its introduction are still able to show the programs, although only in black and white.
In order to be able to separate the color signal from the monochrome one in the receiver, a fixed frequency sub carrier has to be used, this sub carrier being modulated by the color signal.SECAM differs from the other color systems by the way the R-Y and B-Y signals are carried.
First, SECAM uses frequency modulation to encode chrominance information on the sub carrier.
Second, instead of transmitting the red and blue information together, it only sends one of them at a time, and uses the information about the other color from the preceding line. It uses a delay line, an analog memory device, for storing one line of color information. This justifies the "Sequential, With Memory" name.
Because SECAM transmits only one color at a time, it is free of the color artifacts present in NTSC and PAL resulting from the combined transmission of both signals.
Most codecs are lossy, which allows the data stream to transmit faster. This aids transmission across networks, for example the Web, and makes storage more efficient on relatively expensive media, such as non-volatile memory and hard disk, as well as write-once-read-many formats such as CD-ROM and DVD.
There are also lossless codecs, but for most purposes the slight increase in quality might not be worth the increase in data size, which is often considerable. The main exception to this is if the data is to undergo further processing (for example editing) in which case the repeated application of lossy codecs (repeated encoding and subsequent decoding) will almost certainly degrade the quality of the edited file such that it is readily identifiable (visually or audibly or both). Using more than one codec or encoding scheme whilst creating a finished product can also degrade quality significantly (known as conversion loss) (however there are many situations where this is all but unavoidable). The decreasing cost of storage capacity and network bandwidth may obviate the need for lossy codecs for some media over time.
Codecs are often designed to emphasize certain aspects of the media to be encoded. For example, a digital video (using a DV codec) of a sports event, such as baseball or soccer, needs to encode motion well but not necessarily exact colors, while a video of an art exhibit needs to perform well encoding colour and surface texture. There are hundreds or even thousands of codecs ranging from those downloadable for free to ones costing hundreds of dollars or more. This can create compatibility and obsolescence issues. By contrast, lossless PCM audio (44.1 kHz, 16 bit stereo, as represented on an audio CD or in a .WAV or .AIFF file) offers more of a persistent standard across multiple platforms and over time.
Many multimedia data streams need to contain both audio and video data, and often some form of metadata that permits synchronization of audio and video. Each of these three streams may be handled by different programs, processes, or hardware; but for the multimedia data stream to be useful in stored or transmitted form, they must be encapsulated together in a container format.
The widely spread notion of AVI (Audio Video Interlevelled) being a codec is incorrect as AVI (nowadays) is a container format, which many codecs might use (although not to ISO standard). There are other well known alternative containers such as Ogg, ASF, QuickTime, RealMedia, Matroska, DivX, and MP4.
In the Open Source Front, Linux is also equipped with codec’s like DivX, 3iVx, FLAC, VideoLAN (VLC player), ZINC player etc. (more details at http://www.codec-download.com/modules.php?name=Downloads&d_op=viewdownload&cid=52)
Resolving “CODEC Missing Error”
There are some Codec Packs and softwares available on the internet which can solve the “CODEC missing” Problem
Some of them are
1. K-Lite Mega Codec Pack – which can be freely downloaded through http://www.free-codecs.com/k_lite_mega_codec_pack_download.htm (applicable for Windows only)
2. CodecDownload.com http://www.codec-download.com/ this site is home for large variety of CODECs for both Windows as well as Linux support
3. Xvid Organization – supports the Xvid Codec used for AVI format. A very hand decoder which even supports the mobile platforms like Symbian OS and Windows mobile Edition 6. Xvid is open-source software published under the GNU GPL license. The Xvid project releases just source code packages (for developers). Source code distribution has the advantage that it is platform-independent and is suitable for many different operating systems and hardware architectures. Find out more at http://www.xvid.org/Downloads.15.0.html
4. For Audio conversions the swiss knife software available is by illustrate named DB power AMP music converter, which supports OGGvorbis, Windows Media Audio, WIFF, Monkey Audio format etc. visit http://www.dbpoweramp.com/ for details.
5. Realtek also provides the audio codec for windows as well as linux at http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=14&PFid=23&Level=4&Conn=3&DownTypeID=3&GetDown=false
2. For PAL to NTSC and vise versa conversion, you can use Blaze Media Pro software available at http://www.blazemp.com/convert_between_pal_ntsc.htm
3. For more of conversion information refer the conversion guide http://www.howtoconvert.co.uk/howpal2ntsc.htm
4. To convert SECAM to NTSC, you need to use hardware decoders available at http://www.converters.tv/signals/secam_to_ntsc.htm
for any queries, contact me on my email... I'll be more than happy to answer your queries
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