By using this site, you agree to our Privacy Policy and our Terms of Use. Close
redspear on 09 September 2007
Edit Thread
Katilian said:
alpha_dk said:
euclid said:
another common reply to saying we need the extra space is: "when you compress data the quality of the picture and the sound go down... don't you want the best experience money can buy?"

Okay, I know you aren't saying this. I just am going to say, for those who may believe what he is quoting people as saying:

::Very Math Oriented::

::Wiki Article::

::Wiki Article on an easy to understand Lossless algorithm::

Lossless compression is REAL. It is a mathematical truth, and especially in anything digital, lossless compression is cheap and easy.

I was going to have an example here, but it took up too much space. There is a good example on the Huffman page (link #3).

In any case I am not saying this to you euclid. Just to those who might believe what he was saying some people believe.

 

Lossless compression is usually overkill anyway unless it is for achival purposes. Anyone who says they can tell the difference between a 320kbit/s MP3 and the original is either A) in the extremely small (and unfortunate) portion of the population with golden ears, B) studies psychoacoustics, particularly in regard to audio compression and knows what to listen for or C) talking out their ass (which is the most common group). The people in group C also tend to this that monster cable is actually worth the money and that gold connectors really do improve the sound. 

There is a very noticeable difference between a 320 Kbit  MP3 and the Original(recording) and anyone who says they can't hear the differenceis just plain Deaf. I think you may be talking about 320 Kbits MP3 and CD in which case you are mostly right  they do sound similiar but a CD sounds slightly better.

Lossless codecs are used for video diting you do not want to edit in MPEG ever though lots of people do. There are errors in even in lossless codecs all a lossless codec(huffyuv or wavelet compression) means is that the coefficients will equal zero or that you can in fact recover the full image.

Leo-J is only slightly right. Blu-Ray and HD-DVD do suffer from slightly less artifacting than DVDs on an SDTV but overall the difference between the two in 480i is very nominal and not always present depending on how well the studio encodes the DVDs. Also the new DVD standards allow for ATSC support which does make a difference in terms of color but you wouldn't be able to notice that on NTSC or PAL. They use MPEG and otehr lossy codecs for archiving in fact it is very good for that. You can acheive very close replicas with lossy codecs but because of their structure they suck for editing.

Take MPEGs for example It is at its core  a discrete cosine transform(JPEG[Iframe]) where the next frame adds values ot the coefficients that change in the previous frame(P Frame) and than the next may add values to the coefficients that change in the previous and next frame(B frame). the result with the correct quantizier and bitrate can be artifact free but when trying to slice the video up it losses the previous or next frame and since the coefficients do not add to zero data is loss making it a crappy codec to work with when you intend to make a lot of changes and do tons of cuts.