GUIDE: How To Properly Encode Dolby Digital Audio (AC3)

[nikitenko.p]

i have never tried that, i imagine that it is not a type for the begginer.. especially one who is as uncorodinated as myself. Are the positions similar to normal, or are they specialised to be done without sight?

[nike22]

I also want to know the answer to this question.

[tebasuna51]

Please, clarify the question.

[krosswindz]

Is there any guidelines as to what should be the minimum bitrate that should be chosen for AC3 files. I read some where that for 5.1ch AC3 the "legal" minimum bitrate would be 384 kbps. I looked into the encoding guidelines (link available in the first post) it doesnt seem to mention any such limit though it has recommended settings.

[krosswindz]

^ Is there some documentation that one can refer to decide on the minimum bitrate that one can use for different channel setup.

[tebasuna51]

^ Is there some documentation that one can refer to decide on the minimum bitrate that one can use for different channel setup.
I don't know docs, the limits using Soft Encode are:

Low bitrate minimum [recommended]:
(1.0) 56, 64, 80, [96]
(2.0) 96, 112, [192]
(3.x) 128, 160, [256]
(4.x) 192, [384]
(5.x) 224, 256, 320, 384, [448], 512, 576, 640

[krosswindz]

I don't know docs, the limits using Soft Encode are:

Low bitrate minimum [recommended]:
(1.0) 56, 64, 80, [96]
(2.0) 96, 112, [192]
(3.x) 128, 160, [256]
(4.x) 192, [384]
(5.x) 224, 256, 320, 384, [448], 512, 576, 640

These are the very same settings from Dolby Documentation that I specified in my earlier post. What you say from this is that technically it is legal to gave 224kbps 5.1 AC3 soundtrack.

[tebasuna51]

Audio bandwidth (filtered signal) for AC3 5.1:
224 Kb/s 9 KHz
256 Kb/s 12 KHz
320 Kb/s 16 KHz
384 Kb/s 18 KHz
448 Kb/s 20 KHz

[jruggle]

Audio bandwidth (filtered signal) for AC3 5.1:
224 Kb/s 9 KHz
256 Kb/s 12 KHz
320 Kb/s 16 KHz
384 Kb/s 18 KHz
448 Kb/s 20 KHz
From a purely technical standpoint, you can go as low as 32kbps at up to around 20kHz bandwidth as long as the encoded data will fit in the frame. An encoder like Aften will spit out an error if the settings need to be changed (bitrate raised or bandwidth lowered). Of course, quality will generally not be very good at bitrates lower than what is recommended, but Aften leaves that decision up to the user.

[tebasuna51]

Yes, with Aften you can select anything.
I put the values (bitrate limit and bandwidth) used by the old Sonic Foundry Sof Encode like reference.

[geminigod]

Great guide, Somejoe, for a topic that is still relevant and confusing to many today! As a supplement to your guide, I wrote my own 10 cents on the subject in a different forum that some confused souls might find helpful.

http://www.fanedit.org/forums/showthread.php?4989-5.1-surround-sound-dialog-normalization

[mike20021969]

I know post #1 is almost 10 years old, but some, if not all, of the links are now dead.

[filler56789]

I know post #1 is almost 10 years old, but some, if not all, of the links are now dead.

The images with broken links are archived at:

http://web.archive.org/web/20050208121358/http://pages.sbcglobal.net/wilsondr/

[Guest]

It looks like our mod tebasuna has updated the links for us. Please let us know if there are any other things that need to be tidied up.

[szabi]

Hi

Are there any way to encode DTS-HD, DTS-MA or TrueHD audio source to Dolby Digital Plus (EAC3)?
I tried TAudioConverter (http://forum.doom9.org/showthread.php?t=165577), UsEac3to (http://forum.doom9.org/showthread.php?t=145574), PopCorn MKV AudioConverter (http://www.networkedmediatank.com/showthread.php?tid=20887), Eac3to and More GUI (http://forum.doom9.org/showthread.php?t=135095) and Clown_BD (https://forum.slysoft.com/showthread.php?25818-Movie-Only-Copies-eac3to-tsMuxer-amp-ImgBurn-Made-Easy) but none of them could do.
Any suggestion would welcome.

bye
szabi

[tebasuna51]

The only free encoder to eac3 I now is ffmpeg: http://trac.ffmpeg.org/wiki/GuidelinesHighQualityAudio , but I never tested it.

[Richard1485]

@szabi

I am curious as to why you would want to convert gold to lead. In my experience, the three formats that you listed are all better supported than E-AC-3. If space is a consideration, they all have easily extracted cores.

[szabi]

Thnx the link trac.ffmpeg.org (http://trac.ffmpeg.org/wiki/GuidelinesHighQualityAudio). Do you know about any GUI for this?
I use Aften for AC3 encoding, unfortunately the developer of aften seems finish the work to update it for E-AC3. Free E-AC3 encoder available....... (http://forum.doom9.org/showthread.php?t=161383)

@Jeff B
Yes, space saving is the key point.
There was TrueHD source but no AC3 core.
Additionally I wanted to keep the plus channels (7.1 vs 5.1), which is not possible in AC3 but can be in E-AC3.

[Richard1485]

Additionally I wanted to keep the plus channels (7.1 vs 5.1), which is not possible in AC3 but can be in E-AC3.

That makes sense, I suppose. :)