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Not flawed, and I suggest a read of this would be useful . . .

Posted by Martin says (A) on April 4, 2003 at 05:19:22

In Reply to: Is MLP flawed? posted by uzun on April 3, 2003 at 09:41:11:

I suggest doubters read this excerpt from "The MLP lossless compression system" by Gerzon, Craven, Stuart — published at the 17th AES (sorry -- I cannot include illustrations):-

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4.7 Buffering
We have explained that while normal audio signals can
be well predicted, there will be occasional fragments
like sibilants, synthesised noise or percussive events that
have high entropy.

MLP uses a particular form of stream buffering that can
reduce the variations in transmitted data rate, absorbing
transients that are hard to compress.

FIFO memory buffers are used in the encoder and
decoder as shown in Figure 13. These buffers are
configured to give a constant notional delay across
encode and decode. This overall delay is small –
typically of the order of 75ms. To allow rapid start-up or
cueing, the FIFO management minimises the part of the
delay due to the decoder buffer. So, this buffer is
normally empty and fills only ahead of sections with
high instantaneous data rate.

During these sections, the decoder’s buffer empties and
is thus able to deliver data to the decoder core at a
higher rate than the transmission channel is able to
provide. In the context of a disc, this strategy has the
effect of moving excess data away from the stress peaks,
to a preceding quieter passage.

The encoder can use the buffering for a number of
purposes, e.g.:

~ Keeping the data-rate below a preset (format) limit.
~ Minimising the peak data rate over an encoded
section.

Figure 14 shows an example of the latter. The entropy-coded
data rate from the encoder core is shown along
with the buffered result. The buffered data has a
characteristic flat-topped curve. This is not due to
clipping or overload, but to rate absorption in the
encoder/decoder FIFOs.

Another illustration of data-rate minimisation is shown
in Figures 15 and 16. Again the encoded data rate is
plotted through a 30-second 96kHz 24-bit 6-channel
excerpt featuring a close recording of a jazz saxophone.
Figure 15 indicates the underlying compression with the
encoder set to limit above 9·5Mbps. The minimum-rate
encode shown in Figure 16 makes long-term (but low
occupancy) use the decoder buffer.

It should be obvious that the situation in Figure 16 is
preferable if the transmission channel (maybe DVD
disc) has other calls on the bandwidth – for example
bandwidth to transmit associated picture or text.
Figure 17 shows how hard-to-compress signals can be
squeezed below a preset format limit. This 30-second
96kHz 24-bit recording features closely recorded
cymbals in 6 channels. At the crescendo this signal is
virtually random and the underlying compressed data
rate is 12·03Mbps. Buffering allows the MLP encoder to
hold the transmitted data rate below 9·2Mbps by filling
the decoder buffer to a short-term maximum of 86kbyte
(bottom curve).

Figure 18 shows the potential for peak data-rate
reduction on this item with different amounts of
available FIFO memory.

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