Among the MPEG technologies used in practice, the current MPEG-4 offers the highest efficiency during encoding. The main reason is ACE (Advanced Coding Efficiency) - an encoding algorithm that is used in MPEG-4 for the first time.The object orientation in connection with ACE enables very low data rates. It allows storing a complete video movie in full PAL or NTSC resolution and stereo audio (16 bit, 48 kHz) on a single CD-ROM. For clarification: 700 MB of storage is totally sufficient for most movies that run up to 110 minutes. A movie in MPEG-2 format, on the other hand, requires at the same resolution about 11 times more storage space (DVD with 8 GB). While the data rate of MPEG-2 is coupled very closely to the actual profile, MPEG-4 is scalable over a wide area in the audio as well as in the video stream. Audio signals can be processed from 2 kBit/s to 24 kBit/s while video is variable between 5 kBit/s and 10 Mbit/s. Because of this scalability the audio/video data can be adapted specifically to the actual environment. MPEG-2 is mainly used for the large applications: as data format on a video DVD, as data stream in digital television broadcasts and in video editing for digital video broadcasting.
Summary:
1. MPEG2 is the encoding method for DVDs, while MPEG4 is the encoding method of choice for portable devices and online use.
2. MPEG2 encoded video files are much bigger compared to MPEG4.
3. MPEG2 requires a lot more bandwidth for streaming compared to MPEG4.
4. MPEG2 produces the best video quality compared to MPEG4.
5. MPEG2’s compression is much simpler compared to MPEG4.
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