Quality of internal AC3 encoding

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samtroy
Posts: 16
Joined: Sun Apr 19, 2020 9:43 am

Quality of internal AC3 encoding

Post by samtroy »

I was wondering what software exactly is used for the internal encoding of AC3 tracks? How's the encoding quality considered? And if there are more ways in the profile that can further enhance the AC3 quality?

I've already added the "-b 640" switch: -> <extraArgs>-b 640k</extraArgs>

Are there any more switches that can enhance the AC3 encoding quality? Thanks in advance.
Woodstock
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Re: Quality of internal AC3 encoding

Post by Woodstock »

MakeMKV uses ffmpeg's encoders when converting to FLAC and AAC. While I do not remember seeing "AC3" as a conversion profile, it would probably use that, too.

If you are referring to MakeMKV creating an AC3 track for TrueHD tracks, that is simply copying the "lossy core" of TrueHD to its own track.
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samtroy
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Re: Quality of internal AC3 encoding

Post by samtroy »

No, I'm reffering to DTS (HD) to AC3 conversion (for compatability reasons) as talked about in this thread:

https://www.makemkv.com/forum/viewtopic.php?f=10&t=7293.

Yes, maybe it uses ffmpeg's libraries for AC3 encoding as well. I'm just curious if the AC3 encoding quality could be improved by some additional flag or switch (at the cost of some encoding time).

Anyone?
mike admin
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Re: Quality of internal AC3 encoding

Post by mike admin »

samtroy wrote:
Sun Nov 22, 2020 7:26 pm
Yes, maybe it uses ffmpeg's libraries for AC3 encoding as well. I'm just curious if the AC3 encoding quality could be improved by some additional flag or switch (at the cost of some encoding time).
It does use ffmpeg. You can specify any ffmpeg encoder options in conversion profile (look for a flac profile as an example). I doubt that one can get a decent quality out of ac3 though.
samtroy
Posts: 16
Joined: Sun Apr 19, 2020 9:43 am

Re: Quality of internal AC3 encoding

Post by samtroy »

mike admin wrote:
Sun Nov 22, 2020 8:08 pm
samtroy wrote:
Sun Nov 22, 2020 7:26 pm
Yes, maybe it uses ffmpeg's libraries for AC3 encoding as well. I'm just curious if the AC3 encoding quality could be improved by some additional flag or switch (at the cost of some encoding time).
It does use ffmpeg. You can specify any ffmpeg encoder options in conversion profile (look for a flac profile as an example). I doubt that one can get a decent quality out of ac3 though.
You mean because of quality of the ffmpeg encoder or the format AC3 itself? If the ffmpeg encoder is the problem would it be possible to use a differnt/better one with MakeMKV?
dcoke22
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Re: Quality of internal AC3 encoding

Post by dcoke22 »

I'm going to guess that he's referring to going from the lossless DTS track to a compressed AC-3 track, which is limited to 640 kbit/s. It is likely impossible to do that compression in an unnoticeable way. But, AC-3 is widely supported and highly portable.

I'm not aware of any quality problems with audio encoding in FFmpeg.

Hopefully you're also keeping the lossless audio in your rip as well.
mike admin
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Re: Quality of internal AC3 encoding

Post by mike admin »

dcoke22 wrote:
Mon Nov 23, 2020 3:32 pm
It is likely impossible to do that compression in an unnoticeable way. I'm not aware of any quality problems with audio encoding in FFmpeg.
Yes, exactly. It's just a really lossy format.
dcoke22 wrote:
Mon Nov 23, 2020 3:32 pm
But, AC-3 is widely supported and highly portable.
MakeMKV can also do AAC encoding - all profiles, using fdk_aac encoder (superior) or ffmpeg aacenc. It is not so widely supported as ac3, but still much more common than DTS. And you get a superb audio quality.
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