More and more details about the PS3 Slim are starting to emerge as we edge closer to the release date. The latest tech news out of Japan indicates that the PS3 Slim will bitstream Dolby TrueHD and DTS-HD Master Audio direct to your receiver. The HDMI chip on the older PS3 models bitstream new high-def codecs like Dolby TrueHD and DTS-HD MA, having to decode it internally and then sending the data to your receiver via LPCM.
Of course, you are only really going to notice the audio-improvements if you have a really good high-end surround sound set up. What other improvements will emerge over the next week and a bit?
Bitstream audio refers to a succession of 1’s and 0’s transmitted from a player typically to a receiver or A/V preamp. The receiver then decodes this information and amplifies the resulting audio signal to drive your speakers. This information can be transmitted either through SPDIF (optical or digital coax) or HDMI connections depending on the compression method.
Bitstream audio as it comes on disc is usually compressed in 2 ways:
Lossy compression such as:
Dolby Digital Plus
DTS HD High Resolution
Lossless compression such as:
Dolby True HD
DTS HD Master Audio
PCM or Pulse Code Modulation “is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code.” (From the PCM WIkipedia article.) There are compressed forms of PCM audio but the PCM soundtracks that you see in BluRay discs are uncompressed.
Linear PCM or LPCM can be included on the disc itself or the player can derive LPCM from other digital tracks and transport this through the player’s digital connections.
Is there an audible difference?
Given the right equipment and the right conditions a compressed lossless Dolby True HD soundtrack should sound the same as an uncompressed LPCM soundtrack.