AC3 5.1 Passthrough issues

General Discussions
1

I am in the process of converting discs with Handbrake v1.1 for Plex Media Server on a Synology ds716+II (64-bit v1.13.0.5023). When I playback the movies, the dialog that should only come through the center channel is bleeding over to the left, right, and both surrounds. Playback is through a Roku 3 connected to a Yamaha AVR. If I play the DVD directly on the same system, there is no audio bleed-through.

I started the encodes with either the HQ 480p30 Surround or SuperHQ 480p30 Surround presets then change the first audio track to the appropriate 5.1 track and change the encode to AC3 Passthru. Though the receiver indicates a DD5.1 signal, it is definitely not a passthru due to the dialog audio now being on all channels.

Has anyone experienced anything like this? Is there a setting I have wrong in Handbrake? or the Plex MS? or even the Roku? I’m really stumped because it occurs on every DVD, even though they sound find played direct from disc. I even tried a Blu ray with a DTS 5.1 track and got the same results.

2

Never had that happen with Handbrake & AC3 passthru.

  1. Check the sound field on your AVR during playback with the Roku. Make sure it is not modifying things somehow. My Denon has a “Direct” option, which passes the audio directly to the amplifier section unaltered. See if your Yamaha has something similar.

  2. What does Now Playing show? Direct Play / Direct Stream / Transcode
    https://app.plex.tv/desktop#!/status/playing

If the audio is transcoding, then you need to find out why and correct it (will have to pull log files).

  1. Take Handbrake out of the equation. Rip the DVD with MakeMKV, makemkv.com. This copies the video & audio, unaltered, from the disc to a MKV file.

Load the resulting MKV into PMS & play via the Roku. The video will be MPEG2, so it may transcode. The AC3 5.1 track should pass through unaltered (direct play or direct stream). Check Now Playing to make sure the audio is not transcoding.

3

I can’t believe it was so simple. The sound field appears to have been the problem (I’m betting a bouncing dog tail may have been responsible). My AVR must store the field for each input separately, so that’s why the problem wasn’t there when I switched to the dvd player. Before your reply today during troubleshooting I even played a file from the Plex server through the dvd player’s interface, and it worked fine, so I went from thinking it was a handbrake/encode problem to thinking I had a Roku problem.

I had literally spent days troubleshooting, trying different Handbrake settings, and searching internet forums. I couldn’t figure out how no one was experiencing this. For what it is worth for #2 above, it does play the files with Direct Play showing, so I think my encodes are fine, as well.

Thanks so much for the quick input and help, and sorry to waste your time with such a simple problem.

4

Not a waste of time. Stuff like that has bit me, and probably everybody, more than once.

Glad you have it working. :slight_smile: