MP3 Terminologies

What is SMV, AMV, OLED & AAC?

What is LRC? What is TFT? What is MP4? What is AMV? You definitely would encounter many MP3/MP4 related technical jargons that would confuse you as you browse through the contents on this web-site or on other similar web-sites. Here is a concise explanation of some of these terminologies, hope you would find them useful...

SCREENS

OLED

OLED is short for Organic Light-Emitting Diode. It was also known as Organic Electro-Luminescence (OEL). It's primary advantage over the widely used LCD screen is it does not require a backlight to function. As a result, it uses less power and is able to operate longer on portable-devices that battery-depletes very quickly. It is also more soothing to the eyes when operating in darkness. However OLEDs have a shorter life-span than LCD screens.

CSNT

CSNT is the acronym for Color Super-Twist Nematic which is an LCD technology developed by Sharp Electronics Corporation. It is based on a passive matrix, which is less expensive to produce than TFT (active matrix) which is the other widely used LCD technology in the market. CSNT screens offer 140 degrees viewing angles and high-quality colors at half the cost of TFT screens. However, the slower response time restricts CSNT screens to lower-resoutions than TFT screens which have faster response time.

TFT

TFT is the acronym for Thin Film Transistor. This is a type of LCD flat-panel display screen which is controlled by from one to four transistors. TFT LCDs are also known as active-matrix LCDs. TFT LCDs provide the best resolutions of all the flat-panel techniques. It is however also the the most expensive.

Video/Audio File Formats

SMV

SMV is short for SigmaTel Motion Video. SMV files are video/audio format files optimized for decoding by Digital Audio Players with SigmaTel processor chips. Some high-end portable video (MP4) players use this video file format. Though capped at a maximum resolution of 128x128 (or slightly higher resolution), SigmaTel processor-based digital audio players playing SMV files could produce 65535-color videos at 10fps in 22kHz Stereo sound. When transcoded from high-quality original video files, the quality could be pretty impressive on compact-size flash-based MP4 players.

AMV

AMV is a video/audio file format used primarilly in Chinese video (MP4) players. The video-compression ratio is low compared with VCD/DVD formats but file sizes are nevertheless kept small due to smaller resolution screens an frame-rates. Encoding and decoding are less processor-intensive and less-harsh to batteries of these portable devices which deplete relatively fast. Most AMV-based players are restricted to a maximum of 128x128 resolution videos with mono-sound (or 160x120 resolution videos with mono-sound) and could only playback limited-colors videos due to its inherent limitations. However, AMV-based video players are priced very favorably at a fraction of the cost of other MP3/MP4 players.

MP4

The MP4 video/audio file format is video/audio compressed file format based on MPEG 4 Part 14 specifications. It is used mainly for sharing video/audio resources over the internet and for video playbacks in digital audio players. Digital Audio Players that could directly play the MP4 file format without the need for trans-coding are known as real "MP4" players.

Lyrics

LRC

LRC is a lyrics file format with time-tags that is used by many digital audio players for displaying syncronized lyrics when MP3/WMA songs are being played. It turns Digital Audio Players into Karaoke machines that could also be used to help users to learn to sing their favorite songs. LRC files also made it possible for users to conveniently learn foreign languages by listening and viewing simultaneously from multi-lingual Digital Audio Players that have larger screens. LRC files are available for downloading from the web or could be edited by users using a LRC editor. LRC editors are available free-of-charge on the web and together with freely available lyrics of songs on the web, users could easily create LRC files even if they are not readily available from the web. To display syncronized lyrics on MP3 players that supports LRC features, simply rename your LRC file to the same name as your MP3/WMA files (eg [filename].lrc for [filename].mp3 or [filename.wma]). Some MP3 players would automatically display lyrics as long as the valid LRC file is present; others requires you to press another button in order to be able to see the lyrics.

Audio File Formats

MP3

MP3 is a lossy digital audio file format based on MPEG-1 technology. It is able to compress audio sound to 1/11 of the size needed to store it almost without loss of quality. MP3 audio file format is currently the most widely used audio file format in digital audio players.

WMA

WMA is an lossy audio file format invented by Microsoft. It encodes approximately the same audio quality as MP3 file formats. Though it is still not as popular as the MP3 file format, it nevertheless is supported by many Digital Audio Players.

WMA-DRM

WMA-DRM are WMA files that comes with Digital-Rights-Management. They are also known as protected-WMA files because they come with some protection-mechanisms that restricts the use of such files to certain machines. Many online subscription music libraries requires MP3 players to be WMA-DRM ready in order for their files to work on these players.

WAV

WAV or WAVE is an audio file format invented by Microsoft and IBM for use on the PC. Though it can be compressed, it is often used uncompressed at 44100hz, 16-bit per sample for storing maximum uncompressed quality audio at the same level that CD audio encodes. Many digital audio players encodes voice or radio broadcast recorded from the player at various frequencies in the uncompressed WAV format.

AAC

AAC is an lossy audio file format invented by Apple that utilizes better compression and encoding scheme than the more popular MP3 format. Though it is slightly better than the MP3 format, it is not widely used outside the Apple iPod community unlike the MP3 and WMA formats which are de facto audio file formats on most Digital Audio Players.

Audio Outputs

SNR

SNR is short for Signal-Noise-Ratio which is a measure of the signal level relative to to the noise-polluting level. It is usually used by audio equiptment manufacturers to indicate the quality of audio signal that could be produced by their audio products. The measurement unit is dB. Higher value SNR devices produce better audio quality (little noise). Devices that have SNR of 90dB or higher produce good sound with little noise. MP3 players that could produce 95dB or above sounds are premium-grade players that allow you to listen up till the finest harmonics clearly. Speakers that have SNR of 90dB output music with no noticeable hiss.

RMS ouput

How loud a pair of speakers is capable of playing is directly proportional to the RMS (Root-Mean-Square) output it could produce. It is measured by watts-per-channel. If it is a pair of speakers with 2 watts per channel, then the total RMS output is 4 watts. Do not confuse RMS output with PMPO (Peak Music Power Output) which measures the peak unsustainable output an audio device could produce. RMS output gives an accurate indication of what audio devices are capable of producing while PMPO tends to mislead consumers. Portable MP3 speakers rarely exceed 3 watts-per-channel (total 6 watts). Speakers that have a minimum total RMS output of 12 watts are needed to be adequately loud for 1 bedroom.