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Old 4th June 2019, 03:47   #1  |  Link
Blurayhd
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Join Date: Oct 2010
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AC3 TO AAC and

Hi people first I like to sat thank you and please I didnt knew where post this question? annd again excuse me my English because is not my first language but I trying to do my best

So, Im encoding some MKVs that have audio tracks in AC3 620kbps and so far I know for get some lower size on audio I can convert with Eac3to those AC3 to AAC so the converted file wll take lower size than AC3

What my question is, is there some setting that can I set for eventually Can convert again the AAC file to AC3 but keeping the 620kbps just like before keeping the quality?

Thank you in advance!!
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Old 4th June 2019, 04:34   #2  |  Link
Asmodian
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No, unfortunately there is not.

With these lossy codecs you lose quality every time you convert them. The AAC must sound worse than the AC3. The AAC starts with the AC3 as a source and it cannot recreate the source perfectly. Lossy audio compression is a complex process that relies on understanding what frequencies humans will notice in specific situations and discarding frequencies we are less likely to notice. Decoding this audio will also result in new artifacts and the AAC encoder has no way to know what is the important audio and what is an artifact. No one has ever tried to use the resulting PCM to recreate a new AC3 at the same quality as the original AC3, at least to my knowledge, perhaps someone has as a research project.

Something that could tell how the audio was originally encoded and covert the resulting PCM back to the exactly the same encode would be almost magic tech in my mind, maybe not impossible, but very impressive. It would also still not work for encoding to a different codec. The way AAC represents the audio is different internally. These differences are not the kind of thing that could be configured to be the same with a setting, the way the formats are structured is simply very different. Add in the bitrate reduction of the AAC and it is even less imaginable.

It would be sweet though!
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