Tuesday
19th March 2004, 18:28
Hey, ive just been writing one of my uni coursework assignments and while taking a break i suddenly became amazed by the compression ratio of current encoding technology. (I think i may need to 'get out more')
Think about it:
Raw Video Frame (PAL,RGB24) = (720*576*24)/8 = 1244160 Bytes/frame
1 second of this video = (1244160*25)/2^10 = 30375 KBytes/sec
Thus a 2hr movie = (30375*(60^2)*2)/2^20 = 208.57 GBytes/movie
Raw Sound (5.1,48/24kHz,16bit) = [(48000*16*5)+(24000*16)]/8 = 528000 Bytes/sec
Thus a 2hr movie = (528000*(60^2)*2)/2^30 = 3.54 Gbytes/movie
And all this goes on to a 700mb CD , therefore:
96kbits/sec 5.1 AAC Audio = 84.34 Mbytes, 41.97:1 Compression ratio
610.66 MBytes for video = 694.80 kbits/sec, 341.55:1 Compression ratio!
And we complain about the quality of these codec, but it all seems much more impressive when you realise how much work they are actually doing!
Ok, i'll go play in the sun now....
*PS I know raw video/audio isn't really too common, especially with the use of losslees codecs etc.
*PPS My maths may well be abit fuzzy and/or completly wrong :S
*PPS I left 5mb for muxing overhead and decoder filters to be fitted on the cd too! :D
Think about it:
Raw Video Frame (PAL,RGB24) = (720*576*24)/8 = 1244160 Bytes/frame
1 second of this video = (1244160*25)/2^10 = 30375 KBytes/sec
Thus a 2hr movie = (30375*(60^2)*2)/2^20 = 208.57 GBytes/movie
Raw Sound (5.1,48/24kHz,16bit) = [(48000*16*5)+(24000*16)]/8 = 528000 Bytes/sec
Thus a 2hr movie = (528000*(60^2)*2)/2^30 = 3.54 Gbytes/movie
And all this goes on to a 700mb CD , therefore:
96kbits/sec 5.1 AAC Audio = 84.34 Mbytes, 41.97:1 Compression ratio
610.66 MBytes for video = 694.80 kbits/sec, 341.55:1 Compression ratio!
And we complain about the quality of these codec, but it all seems much more impressive when you realise how much work they are actually doing!
Ok, i'll go play in the sun now....
*PS I know raw video/audio isn't really too common, especially with the use of losslees codecs etc.
*PPS My maths may well be abit fuzzy and/or completly wrong :S
*PPS I left 5mb for muxing overhead and decoder filters to be fitted on the cd too! :D