How do youtube video rippers/converters actually work?

27th Jan 2012 04:42 #1

Member

First of all, I'd like to say Hello to everyone on this site, I've been using it for a while just to browse for help, finally decided to become a member.
More to the point, I've been researching different youtube converters for a while now and it really just goes straight over my head, I can't seem to work out how they actually work..
Any help will be appreciated.
Thanks in advance!

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27th Jan 2012 06:11 #2

hech54

Member

Converting TO/FOR YouTube or taking vids from YouTube and converting them to something else?

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27th Jan 2012 06:20 #3

teodz1984

Member

According to wikipedia:

YOUTUBE FORMAT
YouTube originally offered videos at only one quality level, displayed at a resolution of 320x240 pixels using the Sorenson Spark codec (a variant of H.263),[54][55] with mono MP3 audio.[56] In June 2007, YouTube added an option to watch videos in 3GP format on mobile phones.[57] In March 2008, a high quality mode was added, which increased the resolution to 480x360 pixels[58] In November 2008, 720p HD support was added. At the time of the 720p launch, the YouTube player was changed from a 4:3 aspect ratio to a widescreen 16:9.[59] With this new feature, YouTube began a switchover to H.264/MPEG-4 AVC as its default video compression format. In November 2009, 1080p HD support was added. In July 2010, YouTube announced that it had launched a range of videos in 4K format, which allows a resolution of up to 4096x3072 pixels.[60][61]

YouTube videos are available in a range of quality levels. The former names of standard quality (SQ), high quality (HQ) and high definition (HD) have been replaced by numerical values representing the vertical resolution of the video. The default video stream is encoded in H.264/MPEG-4 AVC format, with stereo AAC audio.

TRANSCODING
Transcoding is the direct digital-to-digital data conversion of one encoding to another,[1] such as for movie data files or audio files. This is usually done in cases where a target device (or workflow) does not support the format or has limited storage capacity that mandates a reduced file size,[1] or to convert incompatible or obsolete data to a better-supported or modern format. Transcoding can be performed just while files are being searched, as well as for presentation. For example, Cineon and DPX files have been widely used as a common format for digital cinema, but the data size of a two-hour movie is about 8 terabytes (TB).[1] That large size can increase the cost and difficulty of handling movie files. However, trancoding into a JPEG2000 lossless format has better compression performance than other lossless coding technologies, and in many cases, JPEG2000 can compress images to half-size.[1]

Transcoding is commonly a lossy process, introducing generation loss; however, transcoding can be lossless if the input is losslessly compressed and the output is either losslessly compressed or uncompressed.[1] The process of lossy-to-lossy transcoding introduces varying degrees of generation loss. In other cases, the transcoding of lossy to lossless or uncompressed is technically a lossless conversion because no information is lost, however the process is irreversible and is more suitably known as destructive.