General question about audio bitrates

General questions or discussion about HandBrake, Video and/or audio transcoding, trends etc.
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curtisday
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Joined: Thu Sep 14, 2017 5:05 pm

General question about audio bitrates

Post by curtisday »

Is there anyway to set Ac-3 5.1 audio to 192 bitrate?
Woodstock
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Joined: Tue Aug 27, 2013 6:39 am

Re: General question about audio bitrates

Post by Woodstock »

Depends on what your source is. If it's less than 192, it is worthless to throw bits at it. If it's already AC3, your best bet is to pass it through, rather than doing anything to it.

But, have you tried using the pull-down for the bit rate?
curtisday
Posts: 23
Joined: Thu Sep 14, 2017 5:05 pm

Re: General question about audio bitrates

Post by curtisday »

I thought the pull down was the only way to set the bitrate. I'm converting a lossless MKV so the Audio is starting as DTS-HD MA and I'm trying to make it AC3 5.1 48 and 192 but the lowest bitrate in the pull down is 224. Basically I'm trying to replicate the iTunes Store quality (regardless of how pointless this seems).
Woodstock
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Re: General question about audio bitrates

Post by Woodstock »

192 is possible if you're doing 2-channel stereo; 224 is the minimum total bandwidth for 5.1 down mix of a 5.1 source.

The increase in file size is not really that much, though.
Deleted User 11865

Re: General question about audio bitrates

Post by Deleted User 11865 »

IIRC AC-3 5.1 is encoded at 384 or 448 Kbps on the iTunes Store (just like on DVDs). With a codec like AC-3, encoding 5.1 at 192 Kbps will give you pretty bad audio quality in most cases.

The bitrate ranges offered by HandBrake for AC-3 match those of the official Dolby encoder (or at least did when it was checked).
curtisday
Posts: 23
Joined: Thu Sep 14, 2017 5:05 pm

Re: General question about audio bitrates

Post by curtisday »

When I view the media info on iTunes Purchased movies it lists the AC-3 5.1 as 192kbps. I checked on several titles.
Deleted User 11865

Re: General question about audio bitrates

Post by Deleted User 11865 »

It could be "Dolby Surround" (2 channels).
curtisday
Posts: 23
Joined: Thu Sep 14, 2017 5:05 pm

Re: General question about audio bitrates

Post by curtisday »

There's 2. the dolby stereo audio is 160 and the AC3 5.1 is 192
Deleted User 11865

Re: General question about audio bitrates

Post by Deleted User 11865 »

Can you post a screenshot of the MediaInfo report?
curtisday
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Joined: Thu Sep 14, 2017 5:05 pm

Re: General question about audio bitrates

Post by curtisday »

https://ibb.co/hyROi0

That's from a purchased iTunes movie. It's the 5.1 stream.
curtisday
Posts: 23
Joined: Thu Sep 14, 2017 5:05 pm

Re: General question about audio bitrates

Post by curtisday »

My apologies! after using a different app it says it's 384! so sorry for the mixup!
Deleted User 11865

Re: General question about audio bitrates

Post by Deleted User 11865 »

Not sure which interface to MediaInfo this is, but it's pretty useless… it doesn't show the channel count. But that 192 Kbps stream must be 2-channel.
curtisday
Posts: 23
Joined: Thu Sep 14, 2017 5:05 pm

Re: General question about audio bitrates

Post by curtisday »

It was from VLC. It just gave the wrong info, when i used MediaInfo it said that stream was 384. Sorry for the misunderstanding! My bad!
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