Question about Compression ratio

[Sean--]

Hey guys i'm new to this forum. May i know how to solve following question :

Derive the memory requirement to store one second of uncompressed DVD video, using the following parameters:
frame rate = 30Fps, DVD resolution = 720*480, pixel depth= 24bits/pixel

Also calculate the compression ration achieved by MPEG-2 standard in DVD, assuming the video bitrate for DVD video is 5Mbit/s.

i try to solve this problem, the 1st part answer i calculate is 30.375MB by using calculation

[ (720*480*24)/8 ] / 1024 = 1012.5K
1012.5K*30= 30.375MB

But i dont know how to solve the 2nd part , use the bitrate to calculate the compression ratio part. I hope that you all can help me. Thanks . Have a nice day.

[jagabo]

Don't divide by 8, leave the value in kbits per second. Then just divide the uncompressed kbps by the mpeg kbps.

720 * 480 * 24 * 30 / 1024 = 243000 kbps

243000 kbps / 5000 kbps = 48.6 to 1 compression

But the source isn't normally uncompressed RGB but rather YUY2 video (16 bits per pixel) or YV12 video (12 bits per pixel).

[Baldrick]

1:50 ratio or how you write it. The uncompressed video/dvd video bitrate = (720x480x24x30) / 5 000 000 = 49.7664 = 50.