A codec is a program, capable of encoding or
decoding a digital data stream or signal. The word codec is a short form
of "compressor - decompressor" or "coder - decoder",
takes a raw data file and turns it into a compressed file.
A codec encodes a data stream or signal for transmission, storage or
encryption, or decodes it for playback or editing.
Why we need codec?
video and audio files are
large, so difficult to transfer across the Internet quickly. To help speed up
downloads, mathematical "codecs" were built to encode
("shrink") a signal for transmission and then decode it for viewing
or editing. Without codecs,
downloads would take three to five times longer than they do now.
What are the
common codecs people use?
Some codec examples are MP3, WMA, RealVideo, RealAudio, DivX and XviD. There are many other more obscure codecs.
what is Audio codec?
An audio codec converts analog audio signals into
digital signals for transmission or storage. A receiving device then converts
the digital signals back to analog using an audio decompressor, for playback.
Example of this are the codecs used in the sound cards of personal computers.
what is Video
codec?
An video codec converts analog video signals into
digital signals for transmission or storage. A receiving device then converts
the digital signals back to analog using video
decompressor.
Means if there is a string with double quotes and if you
place a variable in that, it will substitute its value in string.
This is the main difference.
Reference : http://www.scriptvenue.com/2011/10/difference-between-double-quotes-and-single-quotes-in-php/
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