DTS - Volume Loss

I'm having difficulty re-encoding a DTS audio track. Quick overview of process:

- Rip the source m2ts file.
- Extract the .dtshd file.
- Demux the .dtshd file into 7 mono WAV files.
- Edit the video/audio for the film in Adobe Premiere.
- Export 7 mono WAV files.

The goal, obviously, is to do as little damage to the original DTS mix as possible. And up to this point everything seems to be working just fine. Audio quality is consistent throughout each stage of the process.

But I then re-encode the audio using the DTS-HD Master Audio Suite and the resulting file has a massive loss of gain/volume, to the point where the resulting file is virtually unusable for many people. (The audio is still all there: If I play it through my surround sound system I'm able to crank the volume up, with no apparent loss in quality, to the point where it's audible again. But for many computer/speaker setups we've found that people literally can't crank the volume high enough to have an acceptable experience.)

I've tried all manner of troubleshooting, but nothing seems to have any effect on this audio loss and I'm out of ideas. It feels as if I'm taking the same sound out and then putting the same sound back in, so I should get the same result in the final DTS file. But that's not happening for some reason. Really hoping someone with expertise will be able to tell me what I'm doing wrong.

My default settings for the DTS encode:

- Destination Format: Blu-ray Disc (.dtshd)
- DTS-HD Master Audio
- 6.1 Discrete
- Sample Rate: 48000 Hz
- Dialog Normalization: -31 dBFS (No Attenuation)
- Core Bit Rate: 1509 kbps
- TC Frame Rate: 23.796

hamlet9000 said:

- Demux the .dtshd file into 7 mono WAV files.
...

But I then re-encode the audio using the DTS-HD Master Audio Suite and the resulting file has a massive loss of gain/volume...

Click to expand...

How are you decoding the audio?   When decoding DTS-HD MA with eac3to, there's very occasionally a loss in volume, especially with Arcsoft.  (It's not necessarily the case that that there is an error in decoding, just that there is volume loss.)  Try decoding it another way (e.g. decoding with eac3to's built-in decoder if you are using Arcsoft) and seeing if that helps.

I realize that you noticed the loss in volume when encoding, but it's possible that it originates at the decoding stage.  Volume loss is not always as noticeable when editing in an NLE as it is in the final  output.

Yeah. That was my first thought, too. But the volume of each channel remains consistent across original video, original dtshd file, original mono wav, and Premiere-exported mono wav. As a semi-independent confirmation, I can also export a 5.1 mix directly from Premiere and end up with a version that has no volume loss.

The problem seems to exist only once I encode the new dtshd file with DTS-HD Master Audio Suite.

Are you playing back the file in software or did you burn a BD?  If it's the former, it could be a result of the fact that DTS-HD MA, especially 6.1, is not always well supported.  If you haven't done the latter, give it a try.

Did you decode the output file back to WAVs and examine them?  If not, I'd give that a try too.  Looking at waveforms might provide a clue as to what's going on.

Re: Playback. I've tested with MPC, WinAmp, and also the new "Movies & TV" app from Microsoft. I've also muxed into an MKV and played on a WDTV media center through a full surround sound system (Sony receiver); a setup that doesn't have a problem with any other DTS sound. Same behavior across all software/hardware platforms.

Good thought on decoding the DTS file, though. ffmpeg (my primary decode method now), eac3to (what I previously used to decode DTS files), and even BeSweet (as a tertiary check) are all producing errors.

FFmpeg: "This is not a media file or the file maybe damaged."
eac3to: [just crashes out]
BeSweet: "MAXFRAMESIZE not large enough."

All three programs can decode the original dtshd file just fine.

Next step: Verify the dtshd file with DTS HD Streamtools. The "broken" DTS file verifies just fine.

Next step: Re-encode the original WAV files using the DTS suite. This works, FFmpeg can load this dtshd file just fine, and the the original-decoded-encoded-dtshd file doesn't have the volume/gain problems of the edited-then-exported WAV-to-dtshd file.

Note at this stage: I'm working on three different films, and I have now confirmed that this volume/gain problem and "broken" DTS file is occurring with all three. So although at this point it seems clear that something must be going wrong either inside Premiere or with the export from Premiere, the field for what that could be is fairly narrow since it's occurring across three edits.

Unfortunately at this point I'm somewhat stymied again. The export process for the mono WAV files from Premiere simply doesn't have that many bells and whistles to get messed up:

- Format: Waveform Audio
- Audio Codec: Uncompressed
- Sample Rate: 48000 Hz
- Channels: Mono
- Sample Size: 24 bit

(This is the latest CC 2017 version of Premiere, BTW.)

Next: Exporting to AIFF instead of WAV. Same problem (volume/gain loss; broken DTS file).

Next: Convert AIFF to WAV (using Audacity) in the long-shot hope that re-encoding Premiere's export will clear whatever the glitch is. This doesn't work. (Same volume/gain loss; broken DTS file.)

Have also tried reinstalling both Premiere and DTS tools. Same results.

I'm still baffled, but it's 3 AM now my time so I'm going to have to step away from this conundrum for awhile.

(Thanks for all your help, BTW. It's very much appreciated.)

At least we're narrowing things down a bit.  Here are some other steps that might help.

1. Try to encode the WAVs that you exported from Premiere with another encoder and see what happens.
2. Try to export as W64 (of RF64) from Premiere.
3. Upload both your original DTS-HD file and the WAVs that you exported from Premiere, and send me the link via PM.  I'll see if I can shed any light on this.

Okay, for the reference of anyone finding this thread in the future, here's the "solution":

Although using Audacity to re-encode from AIFF to WAV didn't work, what finally did work was:

- Creating an Audacity project file with all the tracks.
- Doing a Gain adjustment across all tracks.
- Exporting as new WAV files.
- Encoding a DTS file using the new WAV files.

The resulting DTS file has no volume/gain loss and is no longer "broken". My best guess is that making the Gain adjustment forced Audacity to re-encode the file in a way that (a) conversion didn't and (b) eliminated whatever element was causing the DTS suite to glitch out. But since there's no clear reason why Premiere would be exporting a buggy WAV file, none of the tools I've used have been able to detect anything wrong with the WAV file, and DTS' own tools don't detect anything wrong with the dtshd files that all other decodes consider broken, that's just a wlid guess at this point.

But if it works, it works.

Thanks again, Captain Khajiit. Your assistance is very much appreciated.

You're welcome, but I don't feel that I did very much that actually helped.  If you want to try to investigate what's going on in Premiere so that you don't have to implement a workaround in future, let me know.  I'm still happy to take a look.

Captain Khajiit said:

You're welcome, but I don't feel that I did very much that actually helped.  If you want to try to investigate what's going on in Premiere so that you don't have to implement a workaround in future, let me know.  I'm still happy to take a look.

Click to expand...

I like to say "Every Sherlock needs a Watson." 
It applies whenever you have something that's just internalized, stuck in your head, and sometimes you just need to externalize to be able to find a solution. Often that just means you need an ear to listen. Even if you don't feel like you helped, you probably helped quite a bit.