Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?

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ProxyCell
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Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?

Post by ProxyCell » Tue Dec 12, 2017 9:01 pm

Description of problem or question
Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?
I have to convert a large number of videos that are from different sources. Their audio tracks are all using different encodings as well.
Can I setup a preset that will make HB determine the sample rate and bitrate and then just match whatever the source was?

HandBrake version
1.0.7 (Mac and CLI)

Operating system and version
macOS 10.13.2 High Sierra

Note: I'm not sure if this is the right board for this question but I didn't want to drop it into the General section either...

Woodstock
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Re: Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?

Post by Woodstock » Tue Dec 12, 2017 11:31 pm

Tricky question - different encoders need different bit rates for the same quality. Are you sure you want what you're asking for?

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JohnAStebbins
HandBrake Team
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Joined: Sat Feb 09, 2008 7:21 pm

Re: Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?

Post by JohnAStebbins » Wed Dec 13, 2017 1:23 am

Samplerate: yes
Bitraterate: no, because it's a bad idea

ProxyCell
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Re: Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?

Post by ProxyCell » Sun Dec 17, 2017 4:13 am

Thank you both Woodstock and JohnAStebbins - I'm curious why I shouldn't just re-use the same bitrate. I have been doing that for my entire life and I figured it was appropriate.

Is there some kind of conversion scale I should use when going from a 192kbit mp3 to AAC or HE-AAC?

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BradleyS
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Re: Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?

Post by BradleyS » Sun Dec 17, 2017 1:32 pm

Each generation of encoding introduces additional losses. There is no relationship between input and output bit rate, other than lossy input generally requires higher quality output to avoid compounding the generational loss. A higher quality source is more compressible with fewer losses.

That said, use what sounds fine to you.

rollin_eng
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Re: Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?

Post by rollin_eng » Sun Dec 17, 2017 1:56 pm

And passthrough whenever possible.

ProxyCell
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Joined: Tue Dec 12, 2017 8:34 pm

Re: Can HandBrake automatically set the sample rate and bitrate of audio tracks to match the source?

Post by ProxyCell » Sun Dec 17, 2017 10:51 pm

Thank you both!

The reason this has come up is I have a few thousand videos to be encoded and they are running mp3 audio tracks - something which we can't use in our streams. So we have to switch over to AAC and I was just thinking about what would be most optimal for the lossy-to-lossy transcoding.

Since they are from difference sources there are a lot of different encodings used. Some are already in AAC and those are being done in a passthrough preset.

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