Lossless Audio, Black Setting, SD Upconversion

How Do I Know?
Love my new Pioneer VSX-03TXH receiver. Love my new Sony BDP-S350 Blu-ray player. But how do I know if Dolby TrueHD or DTS-HD Master Audio is working? I have changed settings on both units and actually read the manuals of both units. Pioneer's website has a picture of the receiver with TrueHD lit up on its front panel, but I have yet to see it on my front panel. My units are connected together only with an HDMI cable. Also, as knowledgeable as I am about home-theater stuff, what is PCM?

Jonathan Macomber

To send a Dolby TrueHD or DTS-HD MA bitstream from the player to the receiver, the player must be set to output the native bitstream. In the Sony BDP-S350, the Audio (HDMI) setting should be Auto, which is the default setting. For the Pioneer receiver, Signal Select should be set to Auto (default) or Digital. When the receiver receives a Dolby TrueHD signal, the "double-D" HD indicator will light on the front panel; I see no TrueHD indicator per se in the drawing of the front panel in the owner's manual. When it receives a DTS-HD or regular DTS signal, the DTS indicator will light up; apparently, there is no way to distinguish between these two bitstreams on the front panel.

Then, you need a Blu-ray disc with a soundtrack in one or the other format. Few if any discs offer both, and some offer neither one. Of those discs that have one or the other, some default to it, but others do not, in which case you have to manually select it in the disc's setup menu.

PCM stands for pulse-code modulation, which is a standard digital-audio format that uses no data compression. It's the format used on CD, DVD-Audio, and some Blu-ray discs. It's the highest-quality digital audio because it's uncompressed, but Dolby TrueHD and DTS-HD Master Audio are theoretically equivalent because they use lossless compression, which means the compression does not discard any information. Thus, Dolby TrueHD and DTS-HD MA can be converted to PCM and should sound identical to the PCM original.

Black is Black
My Samsung HL61A750 has an HDMI Black Level setting. The two choices are Normal and Low. Normal tells the TV to expect an RGB range of 0-255, and Low tells it to expect a range of 16-235. Does this setting have to match the RGB output range setting of my source? How does this affect the display of below-black, above-white, and color banding in general? Which is the better setting to be calibrated to?

If set to receive 0-255, I can see below-black in test patterns and adjust my brightness accordingly. If it's set to 16-235, I have to crank it back up as the black level drops considerably and below-black disappears from the test patterns. I've heard arguments both ways and want to know what the experts are using.

Al Vucic

I always set a TV to display 0-255 so I can see below-black and set brightness precisely. This is also important so the TV can display above-white, which exists in some content, even though video is theoretically limited to 16-235. The source should also be set to output 0-255 so it will send below-black and above-white information. This setting has little to do with color banding, which depends on the bit depth with which color levels are represented.

The Impossible Dream
My quest for an LCD HD display that does right by standard-definition signals is chronicled on my website. When, if ever, do you suppose I'll be able to get a reasonably acceptable image on something like a Samsung LN55A950 for SD channels on DirecTV? I've got a 35-inch Toshiba CRT TV and an even crisper, slightly smaller Sony, and both are more than acceptable.

Best Buy let me hijack their set-up for a while, and aside from a slightly sharper C-SPAN feed, I didn't see much improvement using a Denon receiver with an HQV scaler on the Samsung. And a Friends rerun on TBS (SD) looked truly horrific.

Is there a magic bullet I'm unaware of? Your magazine ran a favorable review of an Edge scaler, but has it passed the TBS test?

Jim Kearney

Upconverting SD so it looks good on a large HD screen is a very difficult proposition, and I agree that most devices don't do a good job of it. David Vaughn reviewed the DVDO Edge for UAV here, and he thought it improved SD quite a bit, though this was more evident on test clips than on real broadcast material.

The best I've seen in this regard is the Toshiba LCD TVs with SRT (Super Resolution Technology); see my review of the 52XV545U. I also know of some excellent work being done in this regard by another processor company, but I can't say any more at this time because I signed a non-disclosure agreement. The prototype I saw at CES did a surprisingly good job even on YouTube content. But don't get your hopes up too high—putting lipstick on a pig does not hide the fact that it's still a pig.

If you have a home-theater question, please send it to scott.wilkinson@sorc.com.

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COMMENTS
Joe's picture

Hi Scott,I all way's wonder why some movies has louder dialog and lower dialog? On my home theater system all my speakers are at the same level via spl meter.

Killerbones's picture

Regarding the BDP-S350 there is a setting called BD-Audio that will need to be changed from Mix to Direct in order to get DTS-MA and Dolby True-HD to be sent via Bitstream.

PS3 Dolby TrueHD Debate's picture

There have been many forums for people trying to get the "Dolby True HD" light to light up when playing Blu-Ray Movies using a PS3. Many people have debated this fact and I would like Home Theaters take on this fact. I too have a PS3 and using my Onkyo 906 amp the only thing I can get the Amp to state is Multichannel. I assume this is decoded signals sent from the PS3. Some people swear up and down using a Samsung BDP-2550 and the True HD light is on they can hear a night and day difference. Can someone please clairify?http://blog.webjak.net/2008/03/01/dolby-truehd-and-dts-hd-ma-on-ps3/

Scott Wilkinson's picture

The Dolby TrueHD indicator on any AVR should never light up when receiving audio via HDMI from a PS3 because the PS3 cannot send a Dolby TrueHD bitstream. Same for DTS-HD. The PS3 decodes these formats to PCM before sending them, so the AVR will indicate that it is receiving multichannel PCM on its front panel. The Samsung BDP-2550 can send Dolby TrueHD and DTS-HD bitstreams, so the AVR will indicate that on its front panel. As for the difference in sound quality between the PS3's PCM stream and the Samsung's Dolby TrueHD stream, I've never made that particular comparison, so I can't say from personal experience. However, I'd be surprised if there's a "night and day" difference, since Dolby TrueHD is lossless and therefore theoretically equivalent to uncompressed audio. There might be a subtle difference in decoders, but I've never heard a big difference in this regard.

Brian's picture

I still find this PCM vs Bitstream extremely frustrating! In April's Issue SCB responded to the letter "Does it take a Ph.D. to figure this stuff out?" Saying all audio streams (soundtrack, seconadary audio, bonus view, etc) could be carried over PCM, set it and forget it! So I was thrilled to have this answered...however...I too have a Samsung P2550 and the manual states PCM wont carry DTS-HD, only Dolby TrueHD, to get DTS-HD you must use bitstream? I'm also further confused by their options of Bitstream Re-encode vs Bitstream Audiophile. Help! I want to use whatever covers all the audio streams and is lossless! Reference page 36 of P2550 manual

Scott Wilkinson's picture

Brian, BD-P2500/2550 firmware version 2.4, which was released on January 6 of this year, adds the ability to decode DTS-HD MA/HR to PCM. So to get lossless primary audio and the secondary audio via HDMI, select the PCM option. Bitstream (Re-encode) mixes the primary and secondary audio and re-encodes it as high-bitrate but conventional DTS, so it's not lossless. Bitstream (Audiophile) sends the original bitstream (Dolby TrueHD, DTS-HD, etc.), but it ignores the secondary audio. You want the PCM option.

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