So I bet you’ve spend hours thinking to yourself… how do they get so much movie into to these tiny disks. Well, I’ll briefly explain some of the important stuff. HDDVD, Bluray and DVD all use lossy codecs. Lossy means details are removed to make size smaller but yet visually look close to the original. Lossless compression is also used. A codec is the compression scheme that is used. Most codecs are very similar using the same basic concepts.

Mpeg-2 is used in DVDs and early Bluray disks. It is the oldest of the HD approved video codecs. It was the replacement for Mpeg-1 and added variable bitrate encoding. Variable bitrate allows the amount of bits allocated to a video segment to be lower when the scene is slow and add more bits to fast motion scenes where more bitrate is needed yet not cause problems with the video buffer. Mpeg2 does quite will on high definition material and is still the most used compression technique for streaming HD. Its large macroblocks are a problem and can sometimes be seen in fast scenes as a blocking effect especially in streaming video. Other formats are replacing it for streaming.

H.264 is part of the Mpeg4 family. It includes better lossless and lossy compression, and smaller macroblocks (which lessens perceived blocking) and many more advanced features. Macroblocks are smaller sections of video that are put together to make the picture. It is used in streaming now as well. It also includes advanced deblocking to further avoid block effect. H.264 is so complex that it requires many times more processing power to compress and decode as Mpeg2. Now that processors are more up to the task, and demand for more HD content in less bitrate is high, h.264 is now a much more viable replacement. Recent Bluray disks tend to use this codec the most however VC1 and Mpeg2 are still used.

VC1 is another mpeg4 derivative. It was made by a group of companies, led by Microsoft as a replacement for Mpeg2. Many of the same companies back h.264 as well. It has many of the features of h.264 but is a leaner version. Its call to fame is it is decoded easier than h.264. The encoder (software that takes the original uncompressed video and compresses it) implementations for VC1 made by Microsoft focused on sharpness of picture and improving the quality of black areas that lossy codecs are notoriously bad on. VC1 is the most used codec on HDDVD.

Well there you have it. I could go into way more detail but it would be tmi honestly. There are great resources online to find out more detailed information but this will get you started. Have fun until next time.