How does Handbrake handle 6.1 surround (also known as "DTS ES")?

General questions or discussion about HandBrake, Video and/or audio transcoding, trends etc.
Post Reply
Dankkh
Posts: 3
Joined: Sun Oct 11, 2020 1:04 am

How does Handbrake handle 6.1 surround (also known as "DTS ES")?

Post by Dankkh »

I know that 5.1 and 7.1 are the most common types of "surround sound" these days; however, I just recently learned about the existence of 6.1, which is used on a small number of DVDs and Blu-Rays. The extra channel is "center-rear", directly behind the viewer's head.

I happen to have a Blu-Ray with 6.1 audio on it, also known as DTS-ES. This article explains it a bit:

https://www.lifewire.com/what-is-dts-es-1846890

Per that article, there are two types of DTS-ES: A "Matrix" version, and a "Discrete" version. I suspect that my particular blu-ray is the "Matrix" version. Please see the MediaInfo listed below. Notice the "Channel(s)_Original" field, and the "ChannelLayout_Original" field:

Code: Select all

Audio #1
ID                          : 2
ID in the original source m : 4352 (0x1100)
Format                      : DTS ES XLL
Format/Info                 : Digital Theater Systems
Commercial name             : DTS-HD Master Audio
Codec ID                    : A_DTS
Duration                    : 2 h 2 min
Bit rate mode               : Variable
Bit rate                    : 4 155 kb/s
Channel(s)                  : 6 channels
Channel(s)_Original         : 7 channels
ChannelLayout_Original      : C L R Ls Rs LFE Cs
Sampling rate               : 48.0 kHz
Frame rate                  : 93.750 FPS (512 SPF)
Bit depth                   : 24 bits
Compression mode            : Lossless
Stream size                 : 3.57 GiB (17%)
Title                       : Surround 5.1
Language                    : Russian
Default                     : Yes
Forced                      : No
Original source medium      : Blu-ray

MediaInfo is basically saying that there are 7 "original channels", but the audio track is still basically a 6 channel track (a.k.a, 5.1). So I'm thinking that the track basically contains some extra data for a center-rear channel, but ultimately it is still a normal 5.1 track. Am I correct on this?

If so, my question is: How exactly does Handbrake handle this weird audio track? Under the Audio tab, it is still listed as a regular 5.1 track, and as such, I can only do a 5.1 mixdown. There is no "6.1 mixdown" available.

I'm guessing that extra "center-rear" data simply gets dissolved into the left-rear, and right-rear? Is that correct? Or is Handbrake not designed to account for this? Thanks in advance.
musicvid
Veteran User
Posts: 3717
Joined: Sat Jun 27, 2009 1:19 am

Re: How does Handbrake handle 6.1 surround (also known as "DTS ES")?

Post by musicvid »

If so, my question is: How exactly does Handbrake handle this weird audio track? Under the Audio tab, it is still listed as a regular 5.1 track, and as such, I can only do a 5.1 mixdown. There is no "6.1 mixdown" available.
Are you reporting a bug that DTS Passthrough is not working with your source in Handbrake?
If so, the required encode logs are the place to start for support.

Or do you just have a lot of time on your hands today?
rollin_eng
Veteran User
Posts: 3558
Joined: Wed May 04, 2011 11:06 pm

Re: How does Handbrake handle 6.1 surround (also known as "DTS ES")?

Post by rollin_eng »

musicvid wrote: Sun Oct 11, 2020 7:14 pm
If so, my question is: How exactly does Handbrake handle this weird audio track? Under the Audio tab, it is still listed as a regular 5.1 track, and as such, I can only do a 5.1 mixdown. There is no "6.1 mixdown" available.
Are you reporting a bug that DTS Passthrough is not working with your source in Handbrake?
If so, the required encode logs are the place to start for support.

Or do you just have a lot of time on your hands today?
No, they are asking what happens to the 6th channel when encoded to 5 channel audio.
Dankkh
Posts: 3
Joined: Sun Oct 11, 2020 1:04 am

Re: How does Handbrake handle 6.1 surround (also known as "DTS ES")?

Post by Dankkh »

rollin_eng wrote: Sun Oct 11, 2020 7:40 pm No, they are asking what happens to the 6th channel when encoded to 5 channel audio.
Correct. I'm not trying to do a passthrough; rather, I'd like to re-encode the audio to AAC without destroying the "6.1" audio data (or at least, mixing it down properly to 5.1).

When opening up this movie in Handbrake, Handbrake reports the audio track is only 5.1. Consequently, if I want to re-encode it, the "mixdown" option only goes up to 5.1 as well. No option for 6.1 exists.

This may not necessarily be a bug; this may just be the nature of how DTS-ES works, because the 6th channel in this case is not a "true" channel, but rather a "matrixed" channel that combines data from both the rear-left and rear-right speakers.

The question is, how does Handbrake mixdown these unusual 6.1 tracks? Is the rear-center channel properly dissolved into the rear-right and rear-left? I'm assuming this is what happens, but I'm not sure. I don't want to lose that data completely.
User avatar
Rodeo
HandBrake Team
Posts: 12604
Joined: Tue Mar 03, 2009 8:55 pm

Re: How does Handbrake handle 6.1 surround (also known as "DTS ES")?

Post by Rodeo »

In the case of DTS-ES "matrix", there is nothing to downmix, audio is actually 5.1 with the center surround channel already mixed into the left/right surround channels, in a way that's optimized for DTS-ES decoders to be able to upmix back to 6.1 and recover most of said channel (HandBrake doesn't do the latter).

In the case of 6.1 audio (such as DTS-ES "discrete" or any other formats supporting 6.1 audio), when 5.1 output is requested, HandBrake does a regular 6.1 -> 5.1 downmix; it obviously doesn't discard channels.
Dankkh
Posts: 3
Joined: Sun Oct 11, 2020 1:04 am

Re: How does Handbrake handle 6.1 surround (also known as "DTS ES")?

Post by Dankkh »

Rodeo wrote: Mon Oct 12, 2020 11:22 am In the case of DTS-ES "matrix", there is nothing to downmix, audio is actually 5.1 with the center surround channel already mixed into the left/right surround channels, in a way that's optimized for DTS-ES decoders to be able to upmix back to 6.1 and recover most of said channel (HandBrake doesn't do the latter).

In the case of 6.1 audio (such as DTS-ES "discrete" or any other formats supporting 6.1 audio), when 5.1 output is requested, HandBrake does a regular 6.1 -> 5.1 downmix; it obviously doesn't discard channels.
Thank you for the response! I assumed this is what's happening, but I wanted to double-check to be sure (you know what they say about making assumptions). I will keep this in mind if I come across any other weird discs with a 6.1 track.
Post Reply