Is this the standard rate for DVDs/Blurays
Presumably there is no sonic penalty for LPCM and its fully compatible
The Directstream sometimes get stuck on a certain rate - so even when I go back to JRiver to play a standard redbook file … its still stuck at 44/24 rather than 44/16 - is there a reason for this?
DVDs are a mess
Digital Rights Management allows each disk played to restrict the highest sample rate that can be played from DVDs (and I presume Blurays) Typically 24/48 or 24/96, but this probably isn’t what you are encountering.
Besides the same answer as question 1: Stereo LPCM may be a separate track mixed as stereo on the disk. But often the player is mixing down a multichannel mix track to stereo for you. Many DVDs are in DTS which, tho it can look like stereo LPCM is really encoded multichannel and will sound like noise when played directly, but most players can decode DTS and then provide either a multichannel PCM or more likely a stereo PCM mix. Dolby Digital can be played directly as stereo PCM without a great loss.
The DirectStream never gets stuck at a certain rate or sample width: for example it never down converts 24/96 to 24/48. It always counts the number of samples seen per unit time and reports the answer if it is a standard sample rate - if not it reports —. Similarly the number of bits reported is simply a function of if a lower bit is ever non zero over a period of time: e.g. if the bottom 8 bits are always 0 it reports a 16 bit sample, if the bottom six bits are always zero but the two bits just above that are sometimes a one then it reports 18 bits… if all of the bottom bits are sometimes non-zero then it reports 24 bits.
In general if the player (or the OS) has a volume control that isn’t set to unity (100%) or is doing some digital signal processing (filtering or sample rate change, etc.) then the lower bits are often non-zero and a CD (which only has 16 bits) will be sent as 44.1/24 and so reported by the DS.
In JRiver MC you can use the Audio Path entry on the Player menu to see if JRiver is applying DSP, a volume control or other DSP to what it’s playing. If JRiver isn’t messing with the audio, then your OS must be (or if you are using a sound card to connect to the DS, it must be…)
There’s a How To that describes most of the things to check and explains how to verify that audio isn’t getting messed with on the way to the DS: http://www.psaudio.com/ps_how/how-to-run-a-bit-perfect-test-with-directstream