--> Player (Foobar) --> OS Audio Layer (DirectSound? Waveform API?)( Better use WAS API or ASIO for Low Latency )
--> AC97(x) or HD Audio or PCI, PCI Express (如果放CD的話最好支援原生44.1KHz, No SRC)
--> DAC (需要完美DAC 最好不受干擾，板子Layout) --> 後級 Amplifier ( Analog Amplify )(花錢及功力所在)
--> Speaker (材質, 特性...) --> Environmet (環境, 喇叭擺設) --> 人耳 (原音重現？）
http://www.highdefdigest.com/news/show/1064
這篇文章對釐清觀念很有幫助
Blu-ray discs can provide their movie soundtracks in any of the following formats:
Dolby Digital
What it is: The audio format familiar from DVD, Dolby Digital (sometimes known as AC-3) is one of the base standards of Blu-ray. It works basically the same way that it worked on DVD in configurations from 1.0 to 5.1, though it does offer a higher maximum bit rate of 640 kb/s (which is considered audibly indistinguishable from Dolby Digital Plus at the same rate).
Level of support: Full support for Dolby Digital is mandatory in all Blu-ray disc players.
Examples of discs that use it: Almost all Blu-ray discs from Sony, Warner Bros., Paramount, and Lionsgate, among others.
How to get it:
- Toslink or Coaxial SPDIF - Using an SPDIF connection, the Dolby Digital bitstream is sent directly to your receiver for decoding, converting to analog, and amplifying to your speakers.
- HDMI - Depending on the setting chosen in your Blu-ray disc player, the HDMI output can be used to transmit the Dolby Digital bitstream to be decoded in the receiver, or the player itself can perform the decoding to a PCM signal and transmit instead in that form. The receiver will still be needed for digital-to-analog conversion and amplification.
- Multi-channel analog - With the analog connections, the player itself must decode the Dolby Digital bitstream and convert it from digital to analog. This will then be passed to the receiver for amplification. In this case, calibration adjustments such as speaker sizes and channel levels should be entered into the Blu-ray disc player's setup menus, not the A/V receiver's. The quality of the resulting sound will vary depending on whether the Digital-to-Analog (DAC) components in the player are as good as those in the receiver. If the receiver has superior DACs, a digital connection (either SPDIF or HDMI) will be preferred.
DTS
What it is: Sometimes referred to as DTS Encore (though DTS themselves don't seem to use that name anymore), this sound format is another familiar holdover from standard DVD. Blu-ray, however, more ably supports the codec at its higher 1.5 Mb/s bit rate.
Level of support: All Blu-ray disc players are required to support the transmission of a DTS bitstream over a digital connection and internal decoding up to at least 2 channels. Most players (other than early models such as the Samsung BD-P1000) will decode internally to 5.1.
Examples of discs that use it: 'Terminator 2', 'Lara Croft: Tomb Raider'.
How to get it:
- Toslink or Coaxial SPDIF - The DTS bitstream will be sent to your receiver for decoding and processing.
- HDMI - As with Dolby Digital, the HDMI connection can carry the raw DTS bitstream for decoding in the receiver, or the player may decode it to PCM first.
- Multi-channel analog - The Blu-ray disc player will decode the DTS bitstream (only 2 channel decoding is required, but most players will do 5.1) and convert it to analog, after which it will be sent to the receiver for amplification. Once again, the final sound quality will depend on how well the audio components in the disc player compare to those in the receiver.
Dolby Digital Plus
What it is: An enhancement over standard Dolby Digital, DD+ offers higher bit rates and more efficient compression, resulting in improved sound quality. It can also support movie soundtracks up to 7.1 discrete channels (though honestly, the vast majority of Hollywood movies are only mixed for 5.1). On Blu-ray, DD+ is encoded as an extension to a "core" Dolby Digital AC-3 track.
Level of support: Unfortunately, DD+ is optional on the Blu-ray format, and not all disc players are required to support it. Many players will simply read the 640 kb/s core and disregard the extension. As a result, most movie studios prefer to use either basic Dolby Digital AC-3 or some of the other advanced formats.
Examples of discs that use it: 'A View from Space with Heavenly Music' claims a DD+ track, assuming that the packaging and menus aren't just mislabeled.
How to get it:
- Toslink or Coaxial SPDIF - SPDIF cannot carry a full DD+ signal. If you use this connection method, the player will limit output to the Dolby Digital AC-3 core.
- HDMI - If the player does not support DD+, it will simply extract the AC-3 core, in which case see the Dolby Digital listing above. Some players may decode the DD+ to PCM and transmit it over HDMI (any version). Other players will instead choose to transmit the DD+ bitstream to a receiver for decoding, but this requires HDMI 1.3 connections on both ends of the chain.
- Multi-channel analog - Either the Blu-ray player will extract and decode the AC-3 core, or (on some models) will decode the full DD+ and convert it to analog.
DTS-HD High Resolution
What it is: Similar to Dolby Digital Plus, DTS-HD High Resolution is an enhancement over standard DTS that offers higher bit rates and better compression. DTS-HD HR is also encoded as an extension to a "core" DTS track. (Note that DTS-HD HR is sometimes referred to as just "DTS-HD", which can be confusing and possibly misleading).
Level of support: Since this codec is also optional on Blu-ray, many players will only extract the 1.5 Mb/s DTS core and ignore the extension.
Examples of discs that use it: 'Basic Instinct', 'Total Recall'.
How to get it:
- Toslink or Coaxial SPDIF - Because SPDIF cannot transmit a full DTS-HD HR signal, the player will extract the DTS core and send the bitstream for that instead.
- HDMI - If the player does not support DTS-HD HR, it will extract the DTS core, replicating the DTS listing above. Some players may decode the DTS-HD HR to PCM and transmit it over any version of HDMI. Other players will instead transmit the DTS-HD HR bitstream to a receiver for decoding (this requires HDMI 1.3).
- Multi-channel analog - Either the Blu-ray player will extract and decode the DTS core, or (on some models) will decode the full DTS-HD HR and convert it to analog.
PCM
What it is: A PCM track is an exact replication of the studio master, encoded on disc without compression. The benefit to this is that it maintains the purity of the source without any loss of fidelity that may come from compression. The downside is that an uncompressed audio track takes up a tremendous amount of disc space, which may (especially on single-layer BD25 discs) negatively affect the video quality of the movie. While the Blu-ray format is capable of utilizing PCM audio up to 24-bit resolution, studios may choose to encode at 16-bit resolution instead, depending on the bit depth of the original source or concerns about conserving bandwidth (downsampling a 24-bit master to 16 bits is technically not the same thing as compression).
Level of support: All Blu-ray disc players are required to support PCM audio.
Examples of discs that use it: Almost all discs from Sony and Disney, as well as selected titles from Lionsgate and other studios.
How to get it:
- Toslink or Coaxial SPDIF - SPDIF does not have enough bandwidth to carry a full 5.1 PCM signal, so the audio track will be downgraded to 2 channels only. This is generally an undesirable result.
- HDMI - A PCM track can be transmitted in full quality over any version of HDMI and delivered to the receiver for D-to-A conversion and amplification.
- Multi-channel analog - In this case, the player converts the PCM to analog and sends it to the receiver for amplification. The quality of the DACs in the player will determine the final audio quality. If the disc player has inferior DACs to the receiver, an HDMI connection is preferred.
Dolby TrueHD
What it is: Dolby TrueHD is a "lossless" compression codec. Although it is compressed to take up less disc space than a PCM track, once decoded it is bit-for-bit identical to the studio master (at either 16-bit or 24-bit resolution, at the discretion of the studio). It may help to think of it like a ZIP file that holds a PCM track. Once you unZIP the file, you get a 100% identical copy of the original PCM, without compromising any sound quality.
Level of support: TrueHD is an optional format on Blu-ray. And since TrueHD is not built in a core+extension configuration, Blu-ray discs that contain a TrueHD track are also required to contain a standard Dolby Digital AC-3 track for compatibility with players that don't support TrueHD.
Examples of discs that use it: 'Ghost Rider', 'The Fifth Element' (Remastered).
How to get it:
- Toslink or Coaxial SPDIF - SPDIF cannot carry a TrueHD signal. If using this connection type, the player will automatically revert to playing back the standard Dolby Digital AC-3 track instead.
- HDMI - If the player does not support TrueHD, it will revert to the standard Dolby Digital track. Some players may decode the TrueHD to PCM and transmit it over any version of HDMI. Other players will instead transmit the TrueHD bitstream to a receiver for decoding (HDMI 1.3 required).
- Multi-channel analog - Either the Blu-ray player will decode the standard Dolby Digital track, or (on some models) will decode the TrueHD and convert it to analog.
DTS-HD Master Audio
What it is: Another lossless audio codec similar to Dolby TrueHD. The difference between the two is that DTS-HD MA is built in a core+extension configuration (just like DTS-HD HR). Although a DTS-HD MA track takes up more disc space than a TrueHD track, it does not require a secondary standard track for backwards compatibility. Since both DTS-HD MA and TrueHD are lossless, they are both 100% identical in quality to the studio master, and hence identical in quality to each other.
Level of support: Like DTS-HD HR, Master Audio is optional on the Blu-ray format. If the player does not support DTS-HD MA, it can extract the standard DTS core.
Examples of discs that use it: Almost all titles from Fox Home Entertainment.
How to get it:
- Toslink or Coaxial SPDIF - SPDIF cannot carry a DTS-HD MA signal. When using this connection type, the player will extract the standard DTS core instead and transmit that as a bitstream.
- HDMI - If the player does not support DTS-HD MA, it will extract the DTS core. Some players may decode the DTS-HD MA to PCM and transmit it over any version of HDMI. Other players will instead transmit the DTS-HD MA bitstream to a receiver for decoding (HDMI 1.3 required).
- Multi-channel analog - Either the Blu-ray player will decode the standard DTS core, or (on some models) will decode the DTS-HD MA and convert it to analog.
At the time of this writing, only one Blu-ray disc player (the Samsung BD-P1400) supports the transmission of a DTS-HD Master Audio bitstream over HDMI 1.3. No current Blu-ray disc players will yet decode the DTS-HD MA track to PCM internally. All other players are limited to extraction of the standard DTS core. This situation is expected to change in the near future as more player models are released, and manufacturers issue firmware updates to existing players.
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