Difference between Blu-rays and 1080p, 720p rips, DVDs v DVD rips

Blu-ray rips of 50 gb of material often come in around 4-12 gb.

DVD rip of 4.5 gb comes in 700 mb -1.4gb.

What's the difference in quality?

I usually buy only those Blu-Rays and DVDs which have a lot of special features and repeat value or the copies are available for cheap in the piracy market.

Else I download and I think that's the way to go for one time watch movies because else it becomes too expensive if you look at buying every thing. Renting isn't an option as the movies aren't accessible as fast as it is online or the depth of movies in the piracy market..

Ok I'll stop the ranting. My basic question - what's the difference in quality?

Computer AV files usually have three 'chunks' of data. The first chunk is a header that is recognised by the OS and various applications as to the format and usage of the file. The second chunk is the actual audio and video data. The third chunk is a set of indices or offsets that allows the application to navigate through the AV data.

The actual AV data is usually stored using various compression techniques, and this is what determines the size of the file. When the compression is less, the resultant file size will be larger and will be closer to the original in terms of quality. Various file formats suggest different lossy and lossless compression as well as containers and decoders that determine the file size.

Cheers

There is a huge difference in DVD rips Vs Blu-ray rips. You surely won't be able to enjoy a DVD rip on your projector screen. And all of it boils down to the source material resolution. About the quality between difference encoders/compression techniques, I've not much idea.

Blu ray discs come packed with extras, audio options etc. So, the source file won't be 50Gb in size. Same is the case with DVDs.

Between good 11GB 1080p rips and original blu ray, there is just a slight difference in video quality which usually won't wow you.

But they say the uncompressed (DTS-HD MA, Dolby TrueHD) audio tracks found in BD's represent a significant difference in quality over Dolby Digital and DTS tracks. (Haven't tested this as I don't have an HD AVR yet.) Rips usually don't come with uncompressed audio tracks.

And BTW, from my experience, I've found that original DVD's sold in India are sometimes worser in quality than good DVD rips.

The main difference I understand is in the audio...

A rip is basically nothing but a compressed from of video much like MP3. Compression works with a codec that is needed to compress that video. Initially there was Divx, then came Xvid, and the recent one is x264 which is a free software library for encoding video streams into the H.264/MPEG-4 AVC format.
Though there are loads of other video codecs, x264 remains to be the best because of the level of quality it delivers with minium bitrate and also for the fact that it is open source.

One of the major constitute of a Video Streme is the Bitrate, then comes the frame resolution and then color resolution/depth. Bitrate in laymen terms is a measure of the rate of information contained in a video stream, its measured in kbps or mbps. Frame resolution is the size of the video (eg 1920x1080) and color res/death which is specified in Bits is used to represent the color of a single pixel... 24bits being the standard.

Usually when we compress a video using x264 we can reduce the Bitrate and frame resolution (color depth is not touched) to get a lesser file size. Codec x264 is an expert in this. It is (through a very complicated algo) able to restrain the video quality by minimizing the bitrate. Result is we get an almost equal video quality with reduced size.

Next come the Audio, which is also compressed in the process though using a different codec and technique, there by reducing the file size futher. For Audio we have AAC,AC3 and MP3 as the codecs (there are more but these being the standard now), with AC3/AAC used for 6 channel audio.

How much we can reduce the size depends on the bitrate of the Video and the Audio and the frame resolution.

For me a BR compressed with x264 with video bitrate of 5 mbps and a resolution of 1280x720(720p) and an Audio encoded in AC3 with a bitrate of 448kbps works best on my current setup.

One more thing the s/w used for doing the compression also is a major factor of what the size and the quality of the resulting file would be. Two different tools using the same standard for compression might still yield two different files sizes with different A/V quality......

Hope this helps........

Isn't this thread promoting piracy??

Morever the thread starter seems to be very much aware of the what is illegally available for downloading and also mentions that he downloads! Then why doesn't he know the difference?

Dal me kuch kala hai!

I think it'll be difficult to mark this thread to be promoting piracy as in this thread people are mostly talking about compression techniques, advantages/disadvantages etc and not about illegal torrents/download sites. I think this should be alrite according to forum rules. No need to bring out the guns for it yet.

Promoting piracy ??? give me one statement in my entire post that talks anything about piracy???

Sam, you are awesome.