Image Processing Reference
Table G-6 Audio Object Types in MPEG-4 (Continued)
Harmonic Vector XCitation.
Harmonics, individual lines, and noise. A parametric encoder.
Bit-Sliced Arithmetic Coding.
Ultra-Low Delay. This algorithm introduces only 6 milliseconds
of delay. This makes it ideal for telecoms use or live production
with wireless microphones.
Most of these algorithms can be augmented with error-resilient support, in which
case they would be prefaced with the letters ER and would be identified with a different
ID value. These rows are flagged in the ER column of the table.
Some work on describing the complexity of the encoded data in a numeric way has
been done. Processor Complexity Units have been defined for each of these object types in
order to help plan the computing capacity required. You can find out more about this from
the MPEG Industry Forum.
H.264 Profiles and Levels
By comparison with MPEG-4 Part 2, the H.264 codec has very few profiles. That does not
mean it has fewer tools, just that there are fewer definitions of how they are made avail-
able in encoding applications. Table G-7 summarizes the profiles.
The support for levels includes 5 main levels and 10 other sub-levels. The 15 levels in
total are available across all of the profiles.
Table G-7 H.264 (JVT) profiles
Low-latency applications such as videoconferencing.
Designed for broadcasting use.
Previously known as Profile-X. This is designed for streaming applications.
This profile is designed to encode quickly, and as a consequence, no B-slices are permit-
ted. Therefore, pictures can be transmitted in the same order as they are encoded and no
delay is introduced. The following capabilities are supported: