Blu-Ray DTS-HD to AC3

General questions or discussion about HandBrake, Video and/or audio transcoding, trends etc.
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yokokingdommusic
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Joined: Mon Aug 30, 2010 9:40 pm

Blu-Ray DTS-HD to AC3

Post by yokokingdommusic »

Alright, I've got a concern. I need all of my files in an MP4, so using an MKV is not an option (just to be clear off the bat :P ). I am importing my Blu-Rays as MP4's, and I was wondering how good the conversion is to AC3? It seems quieter to me, but that seems to be it. I am using AC3 Passthrough (not ffmpeg). It seems to be turning the DTS track into AC3 for me at a sample rate of 48KHz at 640 kbps. Is this ok??

Is it possible to use the pure DTS trak instead? or can that only be done in MKV?

Thank you so much!
Sean
nightstrm
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Re: Blu-Ray DTS-HD to AC3

Post by nightstrm »

Currently, you cannot put a DTS soundtrack in the MP4 container. 640kbps AC3 is the best you're going to do.
yokokingdommusic
Posts: 18
Joined: Mon Aug 30, 2010 9:40 pm

Re: Blu-Ray DTS-HD to AC3

Post by yokokingdommusic »

Do you think that there is really a noticeable difference?
nogames
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Re: Blu-Ray DTS-HD to AC3

Post by nogames »

yokokingdommusic wrote:Alright, I've got a concern. I need all of my files in an MP4, so using an MKV is not an option (just to be clear off the bat :P ). I am importing my Blu-Rays as MP4's, and I was wondering how good the conversion is to AC3? It seems quieter to me, but that seems to be it. I am using AC3 Passthrough (not ffmpeg). It seems to be turning the DTS track into AC3 for me at a sample rate of 48KHz at 640 kbps. Is this ok??

Is it possible to use the pure DTS trak instead? or can that only be done in MKV?

Thank you so much!
Sean
To get a true MP4 file you should choose AAC as audio codec, AC3 is not officially supported, although most mediaplayers/boxes have no problem with that
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Rodeo
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Re: Blu-Ray DTS-HD to AC3

Post by Rodeo »

nogames wrote:To get a true MP4 file you should choose AAC as audio codec, AC3 is not officially supported, although most mediaplayers/boxes have no problem with that
Welcome to several years ago: http://www.mp4ra.org/codecs.html

AC3 has been in the MP4 specs for a few years now.

Edit: a few years being since August 2008, it seems.
JackNF
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Re: Blu-Ray DTS-HD to AC3

Post by JackNF »

If you're using "AC3 Passthrough" instead of the ffmpeg AC3 encoding then I don't think it's actually getting converted. I ran into this oddity some months back but forgot to post it in the bugs forum, but basically AFAICT if you use "AC3 Passthrough" with a DTS source and an MP4 destination file the raw DTS audio seems to get passed through untouched but then labelled as AC3 audio. Some software players like VLC or Media Player Classic can play them just fine because both AC3 and DTS get handed off to the ffmpeg decoding libraries, but it would still erroneously be reported as AC3 by the player because that's what the header info says. I noticed this behavior BEFORE ffmpeg AC3 encoding was added to Handbrake, so before HB had the capability of encoding to AC3 at all.
Last edited by JackNF on Sun Mar 13, 2011 2:52 pm, edited 1 time in total.
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Rodeo
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Re: Blu-Ray DTS-HD to AC3

Post by Rodeo »

JackNF wrote:I ran into this oddity some months back but forgot to post it in the bugs forum, but basically AFAICT if you use "AC3 Passthrough" with a DTS source and an MP4 destination file the raw DTS audio seems to get passed through untouched but then labelled as AC3 audio.
Unlikely. There are plenty of checks to prevent that sort of thing.

DTS audio source + AC3 passthrough will cause either of the following:

1) HandBrake drops the track

2) HandBrake falls back to the AAC encoder

3) HandBrake falls back to the AC3 encoder

Current versions - except the WinGUI - will do (3); not sure what the WinGUI v0.9.5 does, current WinGUI nightlies do (2) IIRC.
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