Why is TrueHD more demanding than DTS-HD MA?

[Warm Gun]

I just watched a movie with a 24-bit 48 kHz Atmos track. The sound played fine through almost the entire length of the movie, but there were about three scenes in which it cut out very briefly. Went I went back, it played fine. This isn't uncommon. It's much worse with TrueHD tracks above 48 kHz. Those cut out every every few seconds, forcing me to switch to the alternate audio tracks or Dolby Digital partner track. But TrueHD tracks above 48 kHz are very rare, which is why I don't think about it too much. Anyway, I don't think I've ever had any DTS tracks cut out on me, even when they were 96 kHz or higher. Are there more steps in the decoding chain with TrueHD? If so, why would anyone use it, unless it's Atmos?

[d3nt0n]

Was it by chance a disc with seamless branching? I seem to notice more dropouts with TrueHD and branching then with dts.

[Warm Gun]

Originally Posted by d3nt0n

Was it by chance a disc with seamless branching? I seem to notice more dropouts with TrueHD and branching then with dts.

It was a disc with branching, but I didn't watch the disc, I made an MKV copy. I never watch my discs directly. It happens with non-branched movies too. I know it's not my PC, because I'm bitstreaming the audio to the receiver.

Actually, I take back one part of the opening post. There was a single Blu-ray whose uncompressed DTS stuttered consistently for me, both from the disc and from the backup: Edward Scissorhands.

But yeah, far more frequent with TrueHD. Again, maybe just once or twice in the entire runtime, if at all. Always very briefly. Still enough for me to wonder.

[d3nt0n]

Happens with ripped discs too, could actually happen more often depending on what you use to rip it. Something about fixed frame sizes in bitstream audio, I'm no expert on why it happens. DGDemux seems to give the best results with minimal dropouts in my experience.

[slimdude]

Originally Posted by Warm Gun

I just watched a movie with a 24-bit 48 kHz Atmos track. The sound played fine through almost the entire length of the movie, but there were about three scenes in which it cut out very briefly. Went I went back, it played fine. This isn't uncommon. It's much worse with TrueHD tracks above 48 kHz. Those cut out every every few seconds, forcing me to switch to the alternate audio tracks or Dolby Digital partner track. But TrueHD tracks above 48 kHz are very rare, which is why I don't think about it too much. Anyway, I don't think I've ever had any DTS tracks cut out on me, even when they were 96 kHz or higher. Are there more steps in the decoding chain with TrueHD? If so, why would anyone use it, unless it's Atmos?

The bitrate shouldn't have anything to do with a defected audio. If you're having that many issues with the audio it may not be the discs, it could be your blu-ray player or the receiver. I have a Oppo 203 and a Denon 4400 A/V receiver, and I've never had that many audio dropouts, if at all.

[Warm Gun]

Originally Posted by d3nt0n

Happens with ripped discs too, could actually happen more often depending on what you use to rip it. Something about fixed frame sizes in bitstream audio, I'm no expert on why it happens. DGDemux seems to give the best results with minimal dropouts in my experience.

Can I run DGDemux after ripping and remuxing or do I have to start everything over again? Seems odd for that to be the reason when the dropouts happen randomly and not twice in the exact same place.

[Warm Gun]

Originally Posted by slimdude

The bitrate shouldn't have anything to do with a defected audio. If you're having that many issues with the audio it may not be the discs, it could be your blu-ray player or the receiver. I have a Oppo 203 and a Denon 4400 A/V receiver, and I've never had that many audio dropouts, if at all.

If my mediocre receiver that costed a quarter yours did has this issue more often with one codec and especially higher sampling rates of the one, then it still begs the question: is it a more complicated codec?

[slimdude]

Originally Posted by Warm Gun

If my mediocre receiver that costed a third yours did has this issue more often with one codec and especially higher sampling rates of the one, then it still begs the question: is it a more complicated codec?

No, the codecs should decode efficiently for lossless audio the same as lossy, it's just a higher bitrate.

[Warm Gun]

I think it's just TrueHD audio tracks of 9200 kbps or more, actually. It happened two to three times with Social Network and Underworld's Atmos tracks. DTS tracks seem to rarely go that high. DTS:X tracks do, and I can't remember if any of those ever stuttered for me, but I doubt it. The audio isn't defective. It's just too much data and TrueHD being less efficient for whatever reason.

[Warm Gun]

Occurred to me as I watching another Atmos movie until minutes ago that my audio hasn't cut out like this since I started sending the 4K picture straight to my TV a couple of months ago. The receiver seems able to take just the sound of the movie now without stuttering every now and then. The internals also no longer begin to hum like something is overheating after a while. Super high resolution tracks like Akira and My Fair Lady still stutter frequently, but that's different. That's definitely something the receiver can't deal with.

[Canada]

I have never had a problem with Dolby Atmos, Dolby True HD, DTS X or DTS-MA cutting out.

[Tok]

Originally Posted by Warm Gun

Occurred to me as I watching another Atmos movie until minutes ago that my audio hasn't cut out like this since I started sending the 4K picture straight to my TV a couple of months ago. The receiver seems able to take just the sound of the movie now without stuttering every now and then. The internals also no longer begin to hum like something is overheating after a while. Super high resolution tracks like Akira and My Fair Lady still stutter frequently, but that's different. That's definitely something the receiver can't deal with.

Is your AVR getting the audio directly from the display via ARC? If so you may only be getting the legacy Dolby Digital or dts audio codecs. Only the newer eARC supports the lossless versions of Dolby and dts.

Just curious which AVR are you using that has problems if connected directly to it?

[Warm Gun]

Originally Posted by Tok

Is your AVR getting the audio directly from the display via ARC? If so you may only be getting the legacy Dolby Digital or dts audio codecs. Only the newer eARC supports the lossless versions of Dolby and dts.

Just curious which AVR are you using that has problems if connected directly to it?

At the time? No. Source was going to the AVR and then getting sent on to the TV. I removed the DTS core and Dolby Digital "core" tracks from my rips, so the audio tracks had no way to fall to compressed audio. Well, maybe DTS could fall, since that truly does have a core, but I remember it always showed uncompressed sound and I was always able to play DTS:X tracks in DTS:X. I have an Onkyo TX-NR575. Like I said, those audio cutouts on TrueHD tracks were infrequent. Very frequent with the rare 96 and 192 kHz TrueHD tracks, though, and still are.

[Tok]

Originally Posted by Warm Gun

At the time? No. Source was going to the AVR and then getting sent on to the TV. I removed the DTS core and Dolby Digital "core" tracks from my rips, so the audio tracks had no way to fall to compressed audio. Well, maybe DTS could fall, since that truly does have a core, but I remember it always showed uncompressed sound and I was always able to play DTS:X tracks in DTS:X. I have an Onkyo TX-NR575. Like I said, those audio cutouts on TrueHD tracks were infrequent. Very frequent with the rare 96 and 192 kHz TrueHD tracks, though, and still are.

I’m not sure how those core tracks work but yes I always understood that dts:MA built upon the legacy core. I guess I would look at the receiver to see what it indicates. All of your display and AVR need to support eARC to get the lossless codecs to AVR if connecting the source to the display.

[Warm Gun]

Basically, Dolby TrueHD has a compressed Dolby Digital partner track and DTS-HD Master Audio (as you said) contains the compressed DTS. That's the difference. When you're ripping, you have the choice of copying the DTS-HD MA and the DTS core as separate tracks. It's redundant, but helps with compatibility on some computer equipment/programs.

[d3nt0n]

To clarify, you're not ripping the DTS-HD MA and the core DTS as separate tracks. The DTS-HD track still contains the core. It's not possible to remove the core from DTS-HD like you can with TrueHD.

[Warm Gun]

Originally Posted by d3nt0n

To clarify, you're not ripping the DTS-HD MA and the core DTS as separate tracks. The DTS-HD track still contains the core. It's not possible to remove the core from DTS-HD like you can with TrueHD.

Yes, I know. That's why I said it's redundant but probably helps with compatibility on some devices. Or maybe they just do it to save on file sizes.

[PeterTHX]

Originally Posted by Warm Gun

I just watched a movie with a 24-bit 48 kHz Atmos track. The sound played fine through almost the entire length of the movie, but there were about three scenes in which it cut out very briefly. Went I went back, it played fine. This isn't uncommon. It's much worse with TrueHD tracks above 48 kHz. Those cut out every every few seconds, forcing me to switch to the alternate audio tracks or Dolby Digital partner track. But TrueHD tracks above 48 kHz are very rare, which is why I don't think about it too much. Anyway, I don't think I've ever had any DTS tracks cut out on me, even when they were 96 kHz or higher. Are there more steps in the decoding chain with TrueHD? If so, why would anyone use it, unless it's Atmos?

Originally Posted by d3nt0n

Was it by chance a disc with seamless branching? I seem to notice more dropouts with TrueHD and branching then with dts.

There are chipsets out there that take shortcuts and aren't 100% to spec.

TrueHD is actually less DSP/CPU intensive than DTS-MA by a long shot, with much higher efficiency. DTS-MA has to reconstruct a lossy signal who's CBR is 1.5Mbps even with dead silence. TrueHD can effectively go to near zero kbps for material like this - because it is a MLP compressed stream with no lossy core. There is a hidden companion track that is either 448 or 640kbps Dolby Digital.

Because there is no overhead in rebuilding the signal you will find far more media devices on the market that stream TrueHD and many of the first Blu-ray players were able to decode it with just a firmware update. It took a year for DTS-MA outputting players - not even decoding, just outputting the lossless bitsteam - to appear.

And lest anyone forget, there were emergency updates to DSP firmwares because there is a flaw in all DTS-MA decoders - the "DTS bomb", a sudden pop or bang that earned DTS the nickname "Destroy The Speakers" behind the scenes. All playback devices have the firmware patch built in now because it was discovered early and there were only a few receivers/pre-amps out at the time. But theoretically an unpatched receiver from 2008 could be out there...

[PeterTHX]

Originally Posted by Warm Gun

Occurred to me as I watching another Atmos movie until minutes ago that my audio hasn't cut out like this since I started sending the 4K picture straight to my TV a couple of months ago. The receiver seems able to take just the sound of the movie now without stuttering every now and then. The internals also no longer begin to hum like something is overheating after a while. Super high resolution tracks like Akira and My Fair Lady still stutter frequently, but that's different. That's definitely something the receiver can't deal with.

It's entirely possible your HDMI cable is not up to spec.

[Warm Gun]

Originally Posted by PeterTHX

It's entirely possible your HDMI cable is not up to spec.

Impossible. It's the receiver.