Sound is louder on one side

General questions or discussion about HandBrake, Video and/or audio transcoding, trends etc.
Post Reply
dav20011
Posts: 4
Joined: Sun Jun 21, 2020 10:02 pm

Sound is louder on one side

Post by dav20011 »

Hi,

I convert the audio from BDs (usually DTS or DTS-HD) to AC3 Pro Logic II, but I have problems with some movies. When playing the sound with a stereo device the music (does not affect other sounds) is too loud on the right side. The original sound is correct and both input and output are 5.1, so I suspect that it should not even have the possibility to cause such trouble. Some of the problematic movies even have the same audio track in different qualities (DTS and DTS-HD) and if I choose the other track as the source it works fine.

Do you have any ideas on how to fix this (apart from using passtrough)?

mduell
Veteran User
Posts: 7106
Joined: Sat Apr 21, 2007 8:54 pm

Re: Sound is louder on one side

Post by mduell »

As this relates to specific encodes, we'd need to see encode logs, and as a bonus, a sample of the source that reproduces the issue may help.

User avatar
JohnAStebbins
HandBrake Team
Posts: 5575
Joined: Sat Feb 09, 2008 7:21 pm

Re: Sound is louder on one side

Post by JohnAStebbins »

The implementation of pro logic matrixing in HandBrake is not very good and causes such problems. I don't recommend using it. Do you have old equipment that only supports analog upmixing of pro logic for multi-channel? Anything built in the last 20 years is going to have much better all-digital multi-channel capability.

dav20011
Posts: 4
Joined: Sun Jun 21, 2020 10:02 pm

Re: Sound is louder on one side

Post by dav20011 »

Here is the requested log with a sample video: https://cloud.schwaerzle.net/index.php/ ... YNKqkdxGcK
The problem is easily noticeable with the intro music.

I just use pro logic with AC3 because it has the highest compatibility with good compression according to the information I found. Do you have some recommendations for 5.1 sound (supported by most modern devices, high compression with very good quality)? I am also really unsure about the bitrate, some people recommend really high bitrates while others say that these are worthless.

User avatar
JohnAStebbins
HandBrake Team
Posts: 5575
Joined: Sat Feb 09, 2008 7:21 pm

Re: Sound is louder on one side

Post by JohnAStebbins »

Just do AC3 5.1. Pro logic II is a downmix to 2 channels with other 3 channels matrixed in to those 2 channels using fancy phase shift maths. It's very lossy.

musicvid
Veteran User
Posts: 3566
Joined: Sat Jun 27, 2009 1:19 am

Re: Sound is louder on one side

Post by musicvid »

Sometimes, AC3 5.1 gets encoded without the recommended 90 degree l/r phase shift recommended in the original Dolby Digital white paper. Used to be a big problem in DVD authoring programs like DVDA.

Interestingly, the phase shift is there to facilitate PLII decoding, and the telltale symptom is much softer stereo playback, only in the left channel. I've seen this several times in the past.

The quick test is to encode in basic stereo, and see if there is a difference.

I know it sounds like a long shot, but if you can post a clip with the original AC3 5.1 audio intact, I have a way to check it in DVDA. Post such a sample to Drive or Dropbox, not YT because it would get re-encoded.

dav20011
Posts: 4
Joined: Sun Jun 21, 2020 10:02 pm

Re: Sound is louder on one side

Post by dav20011 »

Thank you for the advice.

I uploaded the original DTS audio to same directory (removed the video because it is uncompressed).

musicvid
Veteran User
Posts: 3566
Joined: Sat Jun 27, 2009 1:19 am

Re: Sound is louder on one side

Post by musicvid »

Yes, the encoded AC3 is quite heavy on the right side. There is no apparent l/r phase shift.
So same question. Does it sound normal encoded to basic stereo (no PLII)?

dav20011
Posts: 4
Joined: Sun Jun 21, 2020 10:02 pm

Re: Sound is louder on one side

Post by dav20011 »

Normal AC3 stereo is fine, just checked it.

musicvid
Veteran User
Posts: 3566
Joined: Sat Jun 27, 2009 1:19 am

Re: Sound is louder on one side

Post by musicvid »

That's what I suspected. I suggest just using normal stereo for your encodes, as matrixed PLII is dirty by today's standards, at least by mine.

Also, your receiver/amp may have a PLII setting, which may do a better job with discrete 2ch stereo.

A better method in Handbrake might be to encode Dolby Digital 5.1 from your DTS, which will preserve the discrete 5.1 surround channels. It will automatically downmix to 2ch for your stereo devices; there is no need to encode a separate stereo track.

Post Reply