Jul 15 Podcast #487: Next Generation Audio
We received a few emails of late asking why there are more Blu-ray titles being released with DTS-HD Master Audio vs Dolby True HD. So we thought we’d take a look at the formats and see if we could determine why.
Listen to the show
Today's Show:
Blu-ray Reviews:
News:
- Netflix raising prices as much as 60%American mobile TV watching increases
- Samsung Provides More Info On 3DTV Share
- First-Ever Blu-ray DVD Club to Launch Under Columbia House Club
- Not much demand yet for premium video-on-demand
Other:
- MediaMall's PlayLater brings DVR to internet video -- Engadget
- "Is it repairable or should I replace it"?
- 60,000 hour Projector "bulb"
- Netflix Streaming now available in Puerto Rico
Why are more DTS-HD Master Audio Blu-rays Being Released?
We received a few emails of late asking why there are more Blu-ray titles being released with DTS-HD Master Audio vs Dolby True HD. So we thought we’d take a look at the formats and see if we could determine why.
Dolby True HD (From Dolby Website)
- Delivers 100 percent lossless audio that is bit-for-bit identical to the original studio master
- Supports up to 24-bit/192 kHz audio in Blu-ray Disc
- Provides up to 4:1 compression efficiency, maximizing HD disc space and minimizing bandwidth requirements
- Supports up to 14 channels, with eight-channel playback that takes full advantage of Blu-ray Disc’s capabilities
DTS-HD Master Audio (From DTS White Paper)
- Lossless Audio with variable data rates up to 24.5 Mbps for Blu-ray Disc
- Up to 7.1 discrete channels with a sampling frequency of 96 kHz and 24 bits of signal resolution
- Up to 192 kHz sampling frequency and 24 bits of signal resolution for 2.0 channel
- Speaker Re-mapping with multiple speaker playback configurations for 7.1 channel systems
- Secondary Audio/Sub Audio Stream for supplemental audio content*
If you look at the specs the two formats look very similar when you consider Blu-ray discs. Both are lossless formats so that means what goes in comes out. Theoretically, both formats should sound identical, and in listening tests that we’ve done, about the only difference we can hear is level. So why are more studios going with Master Audio? Here’s what we’ve been able to find out:
- Sony claims that based on an Internet poll consumers prefer DTS-MA. Here is one such poll over at blu-ray.com
- Simpler encoding and more cost effective. - Unverified claim made by former DTS employee
- A good marketing strategy?
- Carry over from the DVD?
So let’s start a discussion here. Do you have an opinion? Chime in!
Reader Comments (13)
51 min ..
WOW !!! you made my day !!
Keep up the good work.
BTW , I'm a listener from Israel
I think DTS-HD rules because you can pull the "core" or DTS 5.1 out of the audio track for down-mixing purposes. My understanding is that for True HD you can not pull out a DD 5,1 out of the audio track. You need to have a separate DD 5.1 audio track , i.e. you dedicate more space to audio formats.
I heard once that the reason for the prevalence of DTS-MA was that blu-rays are required to have a lossy codec on the disc. With Dolby TrueHD they have to also put on Dolby Digital 5.1; with DTS-MA, that's all they have to include because receivers and players can still play the lossy DTS core from the lossless information. So it's less work in mastering the disc.
Ah... I see someone has already covered this. Well, I'll echo the sentiment.
Maybe Craig Eggers from Dolby Labs may know why there are more DTS-HD Master Audio Blu-rays being released than Dolby True HD.
This was a great podcast.
Thanks
Yeah, just to expand on what's already been said about DTS-HD MA vs. TrueHD:
The DTS-HD MA and TrueHD codecs are both bit-for-bit lossless, so, for all intents and purposes, neither holds an advantage over the other just in terms of HD lossless audio quality. But there is still a need to support "legacy" gear with a lossy version of the soundtrack, and that is where DTS has the advantage.
In the case of TrueHD, a separate (often "hidden" - as in, you cannot manually select it, but the player will default to is if the connected receiver cannot accept a PCM or TrueHD signal via HDMI or if an optical or coax S/PDIF connection is being used) lossy Dolby Digital version of the soundtrack must also be included. That's a whole second mix that has to be mastered and stored on the disc.
In the case of DTS, the soundtrack starts with the DTS "core" and then the -ES, -HD and/or -HD MA "extensions" are added "on top" of the "core" to bring the soundtrack potentially all the way up to bit-for-bit lossless.
So the DTS scheme saves a little bit of disc space and it's also a less time consuming mix as two separate soundtracks are not necessary as they are with Dolby. Furthermore, the DTS "core" version is still the 1.5 Mbps DTS codec. So even though it is lossy, it is a higher quality soundtrack than the corresponding lossy Dolby Digital version.
So a better lossy "legacy" soundtrack, less disc space, and no need for two separate mixes. Those are the reasons why DTS-HD MA is more popular on Blu-ray than Dolby TrueHD. At least from what I understand :)
In regards to Netflix:
from what I understand, Netflix has basically undergone some restructuring, with the streaming services and the disc-by-mail services essentially functioning now as two separate businesses. There are now two separate "teams" within Netflix, so the new pricing simply reflects this corporate separation of the two services offered under the Netflix brand.
Since the entire streaming side is looked upon as a completely separate set of licences and agreements by the Studios, I think it makes a lot of sense to separate the streaming from the discs-by-mail. That way, Netflix can focus on securing the best deals in each area without trying to "cross-pollinate" one set of licences with the other.
So, if you want streaming, that's it's own thing and it'll cost you $8/month. If you want discs, that's like a whole separate business now and the plans there start at $8/month.
What I would LIKE to see from Netflix - and what I think most customers expect and what would seem to make the most sense - would be for Netflix to offer "bundled" services, with a discount if you sign up for both streaming and discs. Knock, say, 20% off of the combined price and I think customers would be a lot happier and a lot more likely to consider using both services.
Right now, people are just thinking of the change as a price hike. I think that Netflix needs to do a much better job of communicating their new structure:
Streaming - over here on its own...
Discs-by-mail - over there on its own...
"Bundle" them both together and get a 20% discount.
That's the message I think Netflix should be trumpeting.
The only reason I can think of actually only affects people who have older AV receivers without support for HD audio formats.
In this case 1.5 MBit/s DTS core does have an advantage over 640 KBit/s Dolby Digital that is used instead of TrueHD in such cases.
I don't know why people keep saying that Dolby True HD doesn't have a core stereo mix. Perhaps I'm missing something, but I believe I picked up the following extract from a paper years ago from Dolby:
"One channel extension technique is the method by which MLP Lossless, Dolby TrueHD, and MPEG-2 LII deliver compatible downmixes for soundtracks with expanded channels. In these codecs, a 7.1-channel soundtrack is first downmixed to create a 5.1 mix, which is supplemented by a two-channel extension (which we’ll call “extension B”). The 5.1 mix is then further downmixed to a two-channel stereo mix, and another supplemental stream is created that carries the 3.1-channel “extension A.” So the 7.1-channel program is delivered in three separate components: a two- channel mix, the 3.1-channel extension A, and the two-channel extension B."
@Marty
We aren't referring to the downmix in the number of channels. We're referring to the lossy surround mix (ie. "standard" Dolby Digital or DTS) that is necessary in order for "legacy" gear that does not support TrueHD or DTS-HD to still be able to play back a 5.1 channel soundtrack.
TrueHD contains an "extension" structure that makes it easy to output a stereo (2.0) version, but any component using that stereo downmix still has to use a Dolby TrueHD decoder - it just might be a "limited" decoder, such as the stereo-only TrueHD decoders that were found on the first HD-DVD players.
But we're talking about getting a 5.1 Dolby Digital soundtrack off of the disc. In the case of DTS-HD Master Audio, the exact same DTS-HD MA soundtrack also contains a 5.1 DTS "core" lossy soundtrack that "legacy" gear can decode and output. In the case of Dolby, the TrueHD soundtrack is completely useless to "legacy" gear. Instead, a separate, additional 5.1 Dolby Digital soundtrack is simply included on the disc so that "legacy" gear can still access a 5.1 surround soundtrack.
So the Dolby scheme winds up making it so that two separate soundtracks have to be included on the Blu-ray disc - a 5.1 or 7.1 TrueHD version and a 5.1 Dolby Digital version. With DTS, the lone DTS-HD Master Audio soundtrack is all that is necessary, because even "legacy" gear can use that very same soundtrack, but simply only play back the 5.1 DTS "core" part of it.
Reason is simple..
DTS Master Audio was designated by the Blu-Ray consortium as its defacto standard about 4 years ago...
Apparently the DTS guys worked more closely with the consortium when the Blu-Ray standards were being drafted..
Just my $0.02... ;)
So if I understand it right:
DTS Master Audio always include the lossy and the lossless version (disadvantage for the future when no one uses lossy)
Why do you call the lossy version "the core" I can't see any bit being used for the lossless version.
Dolby TrueHD does only include the lossless version
To be backward compatible they add Dolby Digital 5.1.
So in the first option you have one format/steam including both versions.
in the second option you have two formats/streams each supporting a version.
Beyond the single/dual streams DTS also has the edge (slightly) in bitrate. DTS-HD Master Audio supports up to 24.5 Mbit/s vs. Dolby True HD's 18 Mbit/s.. not that it's a huge difference but combine those two points along with the idea that (according to M Code's post), DTS is now designated the standard..and bingo! DTS ftw..
aAfter listening to this podcast I got out all my meager collection of BD movies and noticed that all the ones with Dolby HD audio defaulted to DD5.1 when the movie played. I had to got to the setup and set the audio to HD. The DTS HD ones that had DD 5.1 on the menus all defaulted to DTS HD audio when the movie played.
I did find one movie set Star Trek The Movie Collection that said Dolby HD audio on the case and in the menu still only played in DD5.1 regardless of what I did..