Originally Posted by turnne1
I am not sure I understand what you are saying
did you mean there is no difference in decoding in the blu ray player and sending PCM to the receiver is no different than sending bitstream to the receiver and having the DAC's in the receiver do the decoding?
if that is what you meant I absolutely disagree
I have a few personal examples that include a Sony S5550 blu ray player, A pioneer Bdp-51 blu ray player , pioneer Elite VSX47 TX receiver and a Pioneer Elite SC 07 receiver...that I spend several hours A and B ing with a Kef 2005.2 system
HUGE differences in what was doing the decoding to my ears
Bottom line...the Sony didn't measure up using its internal decoding
if that is not what you meant can you clarify?
Yes - that's what I'm saying. And I'm also saying that those "huge differences" you heard (people always say this, but I have NEVER... EVER... heard a "huge difference" in decoded movie sound... a "huge difference" is like the difference between $50 Radio Shack speakers and a $500 pair of Paradigm, PSB, or Athena speakers (or something even larger than that))... anyway, if you really heard differences, I'm saying it was playback volume level because there are some (I'm not sure where they come from) inconsistencies in playback volume levels and you CANNOT do comparisons between different decode location without level matching using a test tone and a sound meter. It's just not possible.
You made a statement about the the player decoding to PCM versus the receiver's DACs doing the decoding. Let's be very clear... DACs are Digital-to-Analog-Converters. PCM is digital audio... and the DACs ALWAYS convert PCM to analog audio. DACs NEVER convert TrueHD or DTS-HD MA to analog. Conversion from bitstream (TrueHD or DTS-HD MA) to PCM is a decode process and is not done by DACs. It's a format conversion only. And because of the nature of TrueHD and DTS-HD MA, wherever that conversion is done (disc player or receiver or surround processor) you end up with the same PCM digital bitstream because these are lossless digital audio formats (more on this below). The decode process from the lossless codec to PCM is not arbitrary... you always get the same PCM bitstream from every product... disc player, receiver, or surround processor.
All processing in the receiver is done in PCM mode. So the first thing the receiver does if it is receiving a lossless bitstream is convert the bitstream to PCM - then all the processing, bass management, etc. is applied, THEN the channels are converted to analog. No matter which product (disc player, receiver, surround processor) is doing the conversion from bitstream to PCM, the receiver's DACs are going to convert to analog.
The conversion process from TrueHD or DTS-HD MA to PCM isn't subject to producing different PCM digital bitstreams in different digital products. The TrueHD and DTS-HD MA codecs are lossless formats that always produce the same PCM bitstream when they are decoded from TrueHD or DTS-HD MA to PCM. There's no way I know of to cause 2 different products to produce 2 different PCM bitstreams from the same TrueHD or DTS-HD MA track. Since the PCM bitstreams are always the same, the end-product sound quality is always the same.
Here is an ULTRA-simplified example. Let's say the original uncompressed digital signal is 101010101010 (that's 10 repeated 6 times) and this will be in PCM format. When this is encoded as TrueHD or DTS-HD MA, let's say it's about 1/2 of it's original size, or 6 bits instead of 12. And let's say the compressed bitstream is 110011. Now... when you play this segment of sound back, your options are to send 110011 from the disc player (bitstream) or to send 1010101010 (PCM) from the disc player. If you send 110011 from the disc player, the receiver will convert 110011 to 1010101010 (PCM). The decode process from the codec (TrueHD or DTS-HD MA) to PCM is not whimsical... bits are not changed from the original. That's why these are referred to as lossless codecs. No matter where they are decoded, you end up with the original pattern of 1s and 0s. Lossy codecs ARE subject to potentially altering the decoded bitstream a little from one product to another. But when you are discussing lossless codecs, they are designed to ALWAYS decode to the original pattern of bits regardless of where or what does the decoding.
The only variable I've detected is volume level. What's most puzzling is that 1010101010 should always playback at the same volume level regardless of where it was decoded (player or receiver). The fact that the volume levels aren't always matched mean there's something unexpected in the playback chain. But the bottom line is that differences in volume level, even small ones like 0.5 or 1 dB will always be detected as being "better" than the slightly lower level version of the same PCM bitstream converted to analog.
I do hear differences in ANALOG sound from disc players... but even here extremely precise volume matching MUST be employed. But, in my experience so far, there has been no detectable preference for the disc player sending TrueHD or DTS-HD MA vs PCM from the same soundtracks.