I have suffered heavily with all the different compression formats out there. For the video, they call this the 'video codec', and the audio is completely different, most likely mp3. Video compression works by separating the fast moving bits from the slow moving background, through fancy transform techniques. The eye is attracted to faces and such, and that requires the most detail.
One of the first video codecs was mpeg-2, which is used by satellite channels, and standard dvd's. I'm not too sure how that works, but I believe it only looks at one frame at a time. This makes it possible to get a full movie down to 4-6 Gb.
Now, old mpeg-2 looks rather primitive, but the studios must produce a physical medium, much like the record companies are forced to stick to cd's, which is very old technology. There are now newer video codecs which look at multiple frames, and have greater compression. The most common is mpeg-4, which can be called DIVX or XVID. A further wrinkle is that older movies are DIVX-3, and the PS3 only takes DIVX-4! And try telling the difference!
Nothing much has changed on the audio end. MP3 works by dumping parts of the sound that the human ear can't pick up. We all know how tightly that compresses, and the quality is determined by the bit rate.
Next: converting formats
No comments:
Post a Comment