Audio and Video File Formats: An Introduction

FILE FORMATS

There are several audio file formats in common use. There are fewer video file formats, but audio video file extensions can be confusing. This is just a brief description of what the more commonly used audio and video file formats and systems are.

AAC:Advanced Audio Coding This is the audio file format used by Apple for the iTunes Music Store, and it may appear with the M4A filename extension. It is better than MP3 for sound quality. It was developed as part of the MPEG4 group owned by Dolby (see below).

AU: This audio file format is the standard used by Java, Sun and Unix.

MPEG: Moving Pictures Expert Group There are a number of MPEG types now, described below.

MPEG-1: This is used in digital cameras and camcorders for small video clips. VHS quality playback can be expected from MPEG-1.

MPEG-2: Used for digital satellite TV, professional movie recording and recording of home DVD recordings. Provides provision for multi-channel surround sound recordings.

MPEG-3: MPEG-3 was propose as an entity, but eventually merged into MPEG-2.

MPEG-4: This is the newest MPEG system and is used for streaming internet content. It is also used in portable video recorders and for internet downloads. Required for DivX. It improves digital broadcasting and interactive graphics and multimedia.

MP3: Digital audio files, most commonly used to store and playback music. It compresses the files to about 10% of a normal audio file, and a normal music track will be about 5 -6 MB in size. MP3 stands for MPEG-1 Audio Layer 3, not MPEG-3 as many people think. A typical MP3 audio file is near CD quality.

OGG: An audio file format supporting a variety of codecs, the most popular of which is the audio codec Vorbis. However, MP3 files are much more broadly supported than Vorbis.

RA: Real Audio This format is designed for streaming audio over the Internet. It is a self-contained file format with all the audio information stored within the file itself.

WAV: The simplest of the audio file formats, developed by Microsoft and IBM, and built into Windows 95. It is an uncompressed audio file format with large file sizes (10 x MP3), and does not need further processing to play. The WAV file consists of three blocks of information: The RIFF block which identifies the file as a WAV file, The FORMAT block which identifies parameters such as sample rate and the DATA block which contains the actual data, or music sample.

WMA: Windows Media Audio A digital system invented by Microsoft, and is used in portable digital audio players. Using WMA, a file can be programmed so that it cannot be copied, and can be used to protect copyright.

WMF: Windows Media Format These are audio-video files comprising WMA and video codecs. They provide high quality and media security for streaming and download and play applications on computers.

WMV: Windows Media Video Used in the Windows media Player, this is used to stream and download and play audio and video content.

When dealing with audio and video file formats, you will sometimes notice the term 'codec'. A codec is simply short for encoder-decoder (or compressor - decompressor). A main function of a codec is to compress audio or video data streams so that transmission of digital audio samples and video frames can be speeded up and storage space reduced.

The objective of all codecs is to reduce the file size to a minimum while maintaining audio and video quality. A quick indication of the codec's place in the path of transmission and reception is:

Video device (e.g. camcorder) - video capture card - video digitized - codec (compresses digital info) - result (MPEG2, AVI, WMV etc) - codec (decompress) - video frames - display device.

Between the two codecs the compressed result is transferred to the display device transmitted, stored on file, etc). So to condense the flow even further, we could basically describe it as:

raw data - codec - transmit - codec - play

This is simplistic, but it shows where the codecs are used. Therefore, in order to play a movie, video or piece of music of a certain format, you need a codec in your computer to allow you to decompress the file and play it.

Here is some free software which checks what codec a video system uses, and what codec your system needs to play it:

Codec Tool.

The different video file formats are required to meet the requirements of various video devices. Similarly, audio file formats are designed to meet the needs of the specific delivery methods and storage and playback devices introduced by large corporations such as Microsoft, Sony and Apple. Thus, Sony invented the UMD (Universal Media Disk) for the PSP (Playstation Portable), and Apple introduced AAC (M4A) for its iPod.

Peter Nisbet is the author of many articles on audio and video file systems, their transmission, playback and conversion. More information is available on his websites http://www.legalandfree.com and http://www.online-free-movies.com

A Simple Introduction To Filing Electronic Taxes

Nowadays, every department in the governmental or private sector boast a digital nervous system - as Bill Gates put it in his best seller Business at the Speed of Thought - through which it interfaces with the public, listen to the grievances and carries out or facilitates various services. Our current topic of discussion, is electronic tax filing, it makes use of the digital nervous system of the tax department, and in simple terms, it is the World Wide Web's way of filing your tax returns.

In a way, Internet has revolutionized the way people have access to information. It virtually eliminated the unending delay that used to associate with the process of getting services done from governmental bodies in a big way. In the present context, long gone are the days of unending queues and taxing paper works. The electronic filing has made the submission of tax returns a customer friendly exercise. Let us have a look from close quarters the advantages of electronic filing as opposed to the conventional way of filing returns and study what sizeable change it had made in the whole process.

· The first and foremost reform electronic filing had brought about is that it virtually eliminated the need for going through the exhaustive steps of filling the forms and rushing to the nearest post office to get it posted before the due date.

· Not only the paper work, electronic filing in fact has eliminated all sorts of physical movement required in completing the filing of returns. No more office hopping is required. The only thing you needs is a PC and a reliable Internet connection.

· In electronic filing, any mistake that has invariably crept in is corrected in less time. As every bit of data of the tax payer is available online, there is no wastage of time searching dossiers.

· Electronic filing has also reduced the time lag before receiving your tax refunds. Also, with the online submission, it is possible to take a printout of the filed return at the time of submission to keep it as record. No more requests or visiting offices for the same.

· Electronic filing facilitates payment by credit card.

Also, with electronic filing, the back office processing time has reduced by days. For example, even if the customer had waited till the last day before filing his/her returns, still it is possible to get the filing processed within hours of submission as opposed to the 10 odd day's delay that used to occur during the days of paper returns. As a result, as mentioned earlier, it has become possible to complete the refunds within a couple of weeks since filing.

Here is the process of filing returns by electronic means: The customer first should prepare his tax returns (by oneself or through a tax professional). Once the tax returns are in place, then the filing can be done through an IRS e-file provider. Filing can be done online as well, but if you are not sure about the technicalities, it is better to seek professional help. Generally most tax professionals will be licensed IRS e-file providers. Sign all relevant documents and get a customer copy as a record or for future reference. The IRS e-file provider will then file the returns electronically. Within 48 hours of filing the returns, the IRS will send the customer/IRS e-file provider an acknowledgement specifying the current status (acceptance or rejection as it may apply). If it is a rejection, remedial steps should be taken immediately.

As of now, if filing the returns online by oneself, the service as such is free. But if getting the job done through an IRS e-file provider, he/she may charge you a fee for offering you his/her expertise. As there is no solid rule of law in place governing the charging of fees for electronic filing of returns, the fees charged by different IRS e-file providers may vary and hence, from a customer point of view, it would be better to shop around and find out the cheapest deal possible before hiring one for your service.

Keisha Seaton is the owner of http://my-articles.com. To read moreTax Articles [http://www.my-articles.com/Category/Taxes/96] please visit [http://www.my-articles.com/Category/Taxes/96]