distorted audio PCM track

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dabelstein
Posts: 3
Joined: Sat Aug 11, 2018 7:20 pm

distorted audio PCM track

Post by dabelstein » Sun Dec 16, 2018 5:01 am

Hi
I have a few DVDs that when ripped end up with distorted audio. The tracks are always PCM 16bit, 2 channel, 48 khz, 1536kbs. They are all commercially released DVDs of music clips or concerts.

Strange that when the DVDs themselves are played there is no problem. It is only when the MKV is played.

Does anyone know what might be happening or what I can do to troubleshoot this??
regards

Greg

Woodstock
Posts: 6097
Joined: Sun Jul 24, 2011 11:21 pm

Re: distorted audio PCM track

Post by Woodstock » Sun Dec 16, 2018 5:56 am

What profile are you using?

Generally speaking, MakeMKV does not change audio tracks, unless you ask it to. The FLAC profile is one that will do conversions. I do remember a few requests to convert 16-bit to 24-bit LPCM, but Mike rejected them as throwing lots of zero bits at a non-problem, since there was no advantage. The history notes have nothing LPCM-related since v1.9.2.

One publisher I get a lot of stuff from uses 24-bit LPCM as their primary audio codec, and I have not heard the distortion on those disks. I'd have to look to see what I have with 16-bit.
How to aid in finding the answer to your problem: https://www.makemkv.com/faq/item/8

dabelstein
Posts: 3
Joined: Sat Aug 11, 2018 7:20 pm

Re: distorted audio PCM track

Post by dabelstein » Sun Dec 16, 2018 6:58 am

Hi Woodstock

Thanks for the reply. I appreciate you taking the time to help.

I'm just using the default profile.... I've also noticed that when I play one of the troublesome discs in VLC the audio codec is DVD LPCM....but when i play the same disk as an mkv it is araw...not sure if that has something to do with it.

I also notice that the disks have a lot of "AV sync issues in stream 1 at xxxxx with duration of 1.666ms - audio gap filled with silence"...so many that they end up only being printed to the log file.

regards

greg

Woodstock
Posts: 6097
Joined: Sun Jul 24, 2011 11:21 pm

Re: distorted audio PCM track

Post by Woodstock » Sun Dec 16, 2018 3:28 pm

If MakeMKV is trying to synchronize the audio and video, the silence gaps would be rather noticeable when they get that frequent.

I'd suggest sending the information requested in the FAQ link in my signature to support@makemkv.com for Mike to look at. There might be a different way to keep the audio in sync when the time stamps are that out of wack.
How to aid in finding the answer to your problem: https://www.makemkv.com/faq/item/8

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