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Re: Depends...

195.92.168.169

Posted by NotMe on November 4, 2004 at 10:03:34

In Reply to: Re: Depends... posted by Frank.. on November 4, 2004 at 00:45:53:

>This is probably not entirely true.<

It seems that you still haven't read the AES pre-print that describes the operation of DTS 96/24. As far as I'm aware it is the most detailed document available and what my post is based upon. I thought you would have more sense than to rely on any information you got from a "booth at an exhibition", staffed in all likelihood by marketing drones.

Let me quote some of the document, I've highlighted the most important paragraph in bold for the non-technical on the board, there are no "guesses" or "assumptions" involved.

"The increasing interest in audio coding technology capable of delivering multi-channel audio at sampling frequencies higher than 48kHz and word lengths longer than 16 bits has motivated our development of the DTS core+extension coding technology (4). The challenge with improving established coding systems, such as DTS, relates to the design of the new core+extension bit stream. The existing 48kHz decoders need to recognize and decode the 48kHz core coded data within a new bit stream. To ensure this, the data representing audio components introduced by higher sampling frequency and/or larger word length is transmitted as an extension to the core data. Older generation decoders are both unaware of, and unaffected by, the presence of extension data in the bit stream and in this way continue to operate normally at 48 kHz.

"The generalized concept of core+extension coding is illustrated in Figure 1. To encode 96 kHz LPCM the input audio stream is fed to a 96 to-48kHz down sampler and the resulting 48kHz signal is encoded using standard core encoder as in Figure 1 A). In the core+extension coding scheme that we first introduced in (4):

• The core data is fed to a local core decoder whose output is up sampled in a 48-to-96kHz interpolator resulting in an interpolated core LPCM audio, denoted as signal “2” in Figure 1 A). Both operations are performed in the “Reconstruct Core Audio Components” block.

• In the “Generate Residuals” block the interpolated core audio is subtracted from the delayed version of input 96kHz LPCM audio (signal “1”) to generate the LPCM residual (signal “3”). The “Preprocess Input Audio” block performs the delay operation.

• The extension encoder (“Generate Extension Data” block) processes the residual LPCM signal and outputs the extension data. This data, along with the core data, is assembled in a packer to produce a core+extension bit stream.

"To decode a core+extension bit-stream, Figure 1 B), the unpacker first separates the stream into the core and extension data. The core decoder decodes the core data and produces the core LPCM audio that is next up-sampled to 96kHz using the 48-to-96kHz interpolator. The core decoding and interpolation are both performed in the “Reconstruct Core Audio Components” block. The interpolated core LPCM audio is the same as the signal “2” generated in the encoder. The extension data is decoded using an extension decoder (“Reconstruct Residual Components” block) and its output is added to the interpolated core audio to produce a composite 96kHz 24-bit LPCM audio.

"When a 48khz-only (legacy) decoder is fed the core+extension bit stream, Figure 1 C), the extension data fields are ignored and only the core data is decoded. This results in 48kHz core LPCM audio output."

If there is a more technical or up-to-date white paper that I'm not aware of, then a reference would be welcome.

By-the-way, in your previous message you stated that "standard" DTS was a 16-bit system, when in fact it is a 20-bit system.

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