PCM vs Bit stream input to 1069

[kiwi2000]

I have connected a Panasonic blu ray player model 35 to my system consisting of a rotel 1069 a/v switcher HDMI equipped with version 1.1.
The player is connnected via HDMI to enable me to recieve the most current surround formats from dolby and dts.

By chance I changed the audio settings within the player to bitstream from PCM which is required to recieve HD audio from discs. The display on the rotel then showed either dts or dolby whichever was selected in the disc menu to be bitstreamed. I did this when listening to dvd with only legacy audio.

In PCM the rotel showed "multi" on the display.
There was a huge difference in sound quality between the two with the bitstream signal the best setting by far.

The question for the forum is why would this be the case as are they not essentially the same signal being output?

This also causes concern for the HD audio that I have no choice but to get the player to send out in PCM format.

Does anyone have these two units and if so would they be kind enough to try toggling between bitstream and PCM on the Panasonic player audio menu to see if they can hear a difference between the two on legacy dolby or dts dvd material.

In my case the diference was striking indeed!

[Kevin D]

Essentially, the Dolby and DTS decoders in the 1069 are of much better quality then the player. We'll have to wait until people start demoing the 1570 to see if that holds true for the HD tracks as well.

Kevin D.

[Legairre]

kiwi, make sure the volume the 35 outputs when in PCM mode is the same as in bitstream(check with an SPL meter). If the player decodes and outputs at a lower dB even one or two dB in PCM then the bitstream will appear to sound better because, our brains perceive louder as better.

[kiwi2000]

Legairre wrote

kiwi, make sure the volume the 35 outputs when in PCM mode is the same as in bitstream(check with an SPL meter). If the player decodes and outputs at a lower dB even one or two dB in PCM then the bitstream will appear to sound better because, our brains perceive louder as better

.

I should have mentioned that I already calibrated both to the same level for playback. It is not just louder but a full full sound, richer, crisper, etc.

So if this is the case that output PCM is dependent on the player. besides replacing the 1069 I could upgrade the player for better pcm output.

[Mikael]

The PCM signal is a decoded signal where as the Bitstream is not decoded,so the Bit stream signal will use the DTS and DD decoders in the RSP1069.
I you want better DTS HD and TRUE HD sound get a better Blue Ray or go for the new RSP1570 which can decode all the new surround modes from raw Bit stream.

[bnieman]

Kiwi,

As far as I know the RSP-1069 cannot decode DTS-HD-Master Audio or Dolby True (the two latest uncompressed surround formats)

When you bitstream to the RSP-1069 it defaults to playing the legacy DTS or Dolby Digital track because it does not understand the new formats.

The RSP-1069 can play LPCM which is uncompressed surround sound up to 96,000khz sample rate and 24 bit depth into 7.1 channels, the same as the new surround sound formats.

When you changed the setting on your player to PCM the player started decoding the new formats on the player and sent the audio data unaltered through LPCM retaining all the quality of the new Dolby True and DTS-HD-MA formats. Which explains why it sounds so much better. It's a MUCH higher sampling rate and bit depth and best of all it is uncompressed

You have no need to get a new Blu-Ray player unless you want to increase the quality of your video playback. The only way to get better audio quality would be to buy a Blu-Ray player with better DACs than the RSP-1069 and 7.1 analog out... but a Blu-Ray player like that will cost you around $3,000...

To further clarify, DTS-HD-MA and Dolby True are the same concept as zip files on a PC, you can compress them to a smaller size but can extract them back to their full size and potential. Your player is doing just that when it decodes Dolby True and DTS-HD-MA and converts them into LPCM. No quality is lost, it's a bit for bit reproduction of the Dolby True or DTS-HD-MA track. For audio quality you are relying on the DACs in your preamp/processor and associated amp. The only benefit of preamp/processors with on-board decoding of DTS-HD-MA and Dolby True vs sending the "unzipped" audio in LPCM format is the satisfaction of seeing the little icon light up and display DTS-HD-Master Audio or Dolby True

Stick with what you've got, it's a great setup! And your ears were not fooling you in the least Enjoy the glory of uncompressed master quality sound!

Cheers,
Bryan

[Kevin D]

Kiwi,
When you bitstream to the RSP-1069 it defaults to playing the legacy DTS or Dolby Digital track because it does not understand the new formats.

When you changed the setting on your player to PCM the player started decoding the new formats on the player and sent the audio data unaltered through LPCM retaining all the quality of the new Dolby True and DTS-HD-MA formats. Which explains why it sounds so much better. It's a MUCH higher sampling rate and bit depth and best of all it is uncompressed

Cheers,
Bryan

Re-read his question, I got confused the first time as well. He knows he needs to set it to PCM to enjoy the new formats. He was comparing PCM vs bitstream on regular DVD's with regular Dolby/DTS. With the player and processor decoding equal signals.

Kevin D.

[littlesaint]

Does the Rotel handle LPCM over HDMI the same as that decoded from an encoded bitstream? I find it hard to believe that the audio processor in the BD35 can handle TrueHD and DTS-HD, but has problems with DD and DTS. Also, with regards to lossless HD codecs, there is no better. Lossless is lossless. Any perceived differences would be contingent on how the processor handles the decoded LPCM, not the decoding itself.

[bnieman]

When you set it to PCM on the player are you sure it is outputting a decoded DTS/Dolby Digital signal? It may switch to a PCM stereo track, which if like my setup (B&W 703 left and right speakers with HTM7 center speaker), everything sounds more lifelike out of the 703 speakers which is all a stereo track would be using.

In that same scenario the PCM signal could be uncompressed which would be higher fidelity compared to the Dolby Digital or DTS equivalent.

Let us know if you come to any conclusions!

And Santino,
I don't think it's a stretch for the BD35 to be able to decode TrueHD and DTS-HD, usually it's more of a licensing issue than processing power.

Cheers,
Bryan