DVD-Audiobahn

the reason this would be considered an MLP flaw, if it exists...

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tunenut

(A)

In Reply to: But again not with the MLP spec, but the DVD spec. posted by michi on April 03, 2003 at 17:24:16:

is that MLP is designed to work within the existing DVD spec, not the other way around. So it if overflows its allotted capacity, then it is at fault. Although of course you are right, you could also attack this on the capacity side (DVD spec). It could quite likely be "repaired" by tweaking the predictive algorithm, although this would necessitate a firmware change to existing implementations.

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agreed.. - Dave P 19:29:03 04/03/03 (3)
The purpose of MLP is to take six channels of 24/96 LPCM (about 14Mbps) and pack it down so it fits within the DVD transfer rate of 10.5Mbps. If the algorithm can't do that without filtering the audio first then it's not really lossless, is it?
Dave.
- Re: agreed../ MLP encoder features - Mathias Myka 22:43:51 04/03/03 (0)
  One little piece of information that might clear up things a bit: the MLP encoder will never do any changes of bandwidth, frequency response or whatever on its own. In fact, during the encoding process the resulting MLP data stream is decoded and verified against the original PCM input, just to make sure that the player/decoder output is an exact, bit-by-bit equivalent to the input into the encoder. If this verification step fails, the encoding process is aborted, and you get an error message.
  The Minnetonka version of the encoder has a feature (called ReBit) that allows you to reduce the word size from 24 down to 22, 20, 18 or 16) bits on a per-channel basis in case the encoder should fail with your source material. Until now, I've never needed to use that.
  Mathias
- No, you are wrong. Have you guys even read the MLP paper? - Joe Friday 20:32:32 04/03/03 (1)
  You said:
  > > The purpose of MLP is to take six channels of 24/96 LPCM (about 14Mbps) and pack it down so it fits within the DVD transfer rate of 10.5Mbps < <
  Meridian says otherwise. Have you read their MLP paper? See page 1.
  Here is what they claim: "MLP performs lossless compression of up to 63 audio channels including 24-bit material sampled at rates as high as 192kHz." So, why would Meridian design a 63-channel algorithm for DVD-A? The alg. can be used for DVD-A, but it's purpose or use is of a much wider scope.
  Also, the DVD-A max. rate according to Meridian is 9.6Mbps. See page 9 which states, "In the case of DVD-Audio peak rate is a key parameter because the encoded stream must always operate below the audio buffer datarate limit of 9.6Mbps"
  -Joe Friday ("just the facts")
  - semantics - Dave P 06:52:43 04/04/03 (0)
    The maximum DVD transfer rate is 10.5Mbps, but due to error correction codes the maximum useable bitrate is 9.8Mbps.
    And yes, I'm aware that MLP has greater capabilites than six channel 24/96. My point still stands that the primary purpose of MLP on DVD-A is to compress 6-ch 24/96 so it fits within the current DVD spec and if it can't do this without overflowing its FIFO buffer then it isn't doing lossless compression of the master.
    Personally I don't see the filtering as a big issue. Whether it's a 24kHz filter to get MLP to work (as Frank suggested) or a 40kHz filter to eliminate the ultrasonic noise on DSD, they're both above the audible band so should have minimal effect on the sound.
    Cheers,
    Dave.

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