AAC vs AC3 vs DTS (which one should be chosen for mkv movie files)

… researching…

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Between AAC 5.1 and AC3 5.1, it all depends on what bitrate is used in both formats.

AAC is more advanced lossy audio format than AC3, it will produce better audio quality than AC3 with same bitrate, especialy on low bitrates.

You can’t compare low bitrate ACC against high bitrate AC3, in which the latest will produce higher quality audio in that case, of course.

With DTS, For example a DTS-HD Master Audio, lossless 24-bit 96 kHz with 1.5 Mbit/s bitrate will produce superb audio quality, superior than ACC or AC3 at any bitrate.

Unfortunately not all players plays DTS, or AAC

I usually keep DTS as possible, because there is players that can play DTS but not DTS-ES, etc….the same with AAC which I convert always to AC3

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If AAC is a superior format comparing to AC3?

Short answer:  it’s debatable. AAC was really designed to replace MP3 rather than to replace AC3. The fact that AAC supports multiple channels is just a bonus but it really was designed for uses like iTunes rather than as a movie soundtrack.

AAC is lossy as is AC3. MKV is a container, not an audio format. AAC does support 5.1. Whether it is better than AC3 or not is certainly debatable but given that it is a lossy format converting from AC3 to AAC is going to entail some loss of quality, even if you can’t perceive it. I personally find AAC cumbersome to deal with as it is not valid for DVD or BluRay audio. AAC has its supporters, some of whom are Apple fanboys. I can tell you that my personal opinion is that it’s a fine codec but I remain skeptical that it is superior to others. If it actually is superior my feeling is that it is so by such a slim margin that most people could never actually tell the difference between it and another good codec in a blind test.

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Q: I keep reading in DVD guides that the bitrate of AC3 audio on DVDs is limited to 448kbps, even though the maximum bitrate for 5.1 AC3 is 640kbps. Is this true? Is 640kbps considered out of spec, or just considered not proven to work reliably?

A: Bitrates of 512K and higher present problems to some multiplexers and players because the size of the audio frame exceeds the payload size of one DVD pack (2025 bytes). 512K frames are 2048 bytes, 576K frames are 2304 bytes, and 640K frames are 2560 bytes.

Q: So how does DTS get away with it with 1536kbps streams?

A: A DTS audio frame has 1/3 the number of samples as AC3 (and 1/3 the duration), which would imply that 1536 take up the same space as a 512 AC3. But the actual bitrate of “1536 Kbps DTS” is 1509.75 Kbps, and that requires only 2012 bytes.

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