I found a very interesting article by Robert Harley in AVGuide.com He defines two different functions involved in decoding a lossless BluRay:
unzipping of the TrueHD bitstream to PCM, and the conversion of that PCM to analog. The former is best done in the player; the latter in the controller.unzipping of the TrueHD bitstream to PCM, and the conversion of that PCM to analog. The former is best done in the player; the latter in the controller.
Here is the detail:
"...The confusion arises from the term decode. Heres how it works. The film soundtrack starts out as high-res PCM (Pulse Code Modulation) audio and is encoded into, for example, a Dolby TrueHD bitstream for storage on the Blu-ray disc. (Ill use TrueHD as a stand-in for all the new audio formats.) You can think of this process as creating a Zip file on a PC.
The file must then be unzipped on playback; that is, the Dolby TrueHD bitstream must be decoded back into multichannel linear PCM audio for conversion to analog. This decoding can take place in the Blu-ray player or in the controller.
If the decoding to PCM takes place in the player, the controller receives high-res PCM over the HDMI interface. The controller then converts the PCM to analog for listening.
If the decoding of Dolby TrueHD to PCM takes place in the controller, the HDMI interface carries the TrueHD bitstream.
It really makes no difference sonically where the decoding takes placein the player or in the controller. In fact, it may be advantageous to decode in the Blu-ray player rather than the controller because the format has the capability of mixing different audio sources on the fly during playback. An example of this is a directors commentary posted on a movie studios website after the Blu-ray disc has been released; you can watch and listen to the movie from disc as well as hear the directors commentary streamed from the web. [ED NOYE - this is the BD 2.0 standard only where content can be accessed from the Internet assuming of course that the studio created it.]
There are many other examples of Blu-rays interactivityfeatures that are lost if the TrueHD-to-PCM decoding doesnt take place in the Blu-ray player.
Not all Blu-ray players can perform this unzipping of TrueHD bitstreams to PCM. It requires a fair amount of DSP horsepower, making it an expensive (for now) feature for disc-player manufacturers. I expect, however, that all next-generation players will have this capability.
For a full listing of Blu-ray player features (including whether the player can output decoded PCM), go to www.idoblu.co.uk/page2%20Blu-r... Scroll down the page to see the player features. Youre looking for blue boxes in the True-HD and DTS-MA columns.
unzipping of the TrueHD bitstream to PCM, and the conversion of that PCM to analog. The former is best done in the player; the latter in the controller.unzipping of the TrueHD bitstream to PCM, and the conversion of that PCM to analog. The former is best done in the player; the latter in the controller.
Here is the detail:
"...The confusion arises from the term decode. Heres how it works. The film soundtrack starts out as high-res PCM (Pulse Code Modulation) audio and is encoded into, for example, a Dolby TrueHD bitstream for storage on the Blu-ray disc. (Ill use TrueHD as a stand-in for all the new audio formats.) You can think of this process as creating a Zip file on a PC.
The file must then be unzipped on playback; that is, the Dolby TrueHD bitstream must be decoded back into multichannel linear PCM audio for conversion to analog. This decoding can take place in the Blu-ray player or in the controller.
If the decoding to PCM takes place in the player, the controller receives high-res PCM over the HDMI interface. The controller then converts the PCM to analog for listening.
If the decoding of Dolby TrueHD to PCM takes place in the controller, the HDMI interface carries the TrueHD bitstream.
It really makes no difference sonically where the decoding takes placein the player or in the controller. In fact, it may be advantageous to decode in the Blu-ray player rather than the controller because the format has the capability of mixing different audio sources on the fly during playback. An example of this is a directors commentary posted on a movie studios website after the Blu-ray disc has been released; you can watch and listen to the movie from disc as well as hear the directors commentary streamed from the web. [ED NOYE - this is the BD 2.0 standard only where content can be accessed from the Internet assuming of course that the studio created it.]
There are many other examples of Blu-rays interactivityfeatures that are lost if the TrueHD-to-PCM decoding doesnt take place in the Blu-ray player.
Not all Blu-ray players can perform this unzipping of TrueHD bitstreams to PCM. It requires a fair amount of DSP horsepower, making it an expensive (for now) feature for disc-player manufacturers. I expect, however, that all next-generation players will have this capability.
For a full listing of Blu-ray player features (including whether the player can output decoded PCM), go to www.idoblu.co.uk/page2%20Blu-r... Scroll down the page to see the player features. Youre looking for blue boxes in the True-HD and DTS-MA columns.