AC3 encoding...what kbps per Channel?

[DanDare1983]

Hi,

AC3 pretty much works on anything (correct me if I'm wrong) so I'm encoding all audio from my movies to AC3 for compatibility reasons. Is there a correct t way of encoding in regards to kbps per channel? I know 640 is for 5.1 but what would 1.0 and 2.0 tracks be? Also if I'm dealing with a 7.1 or a 4.0 track what would I encode to in terms of AC3? Any help would be appreciated

[SeeMoreDigital]

Hi,

AC3 pretty much works on anything (correct me if I'm wrong) so I'm encoding all audio from my movies to AC3 for compatibility reasons. Is there a correct t way of encoding in regards to kbps per channel? I know 640 is for 5.1 but what would 1.0 and 2.0 tracks be? Also if I'm dealing with a 7.1 or a 4.0 track what would I encode to in terms of AC3? Any help would be appreciatedPersonally I would not recommend generating 'mono' (centre only) 1.0-channel encodings. You're better off generating two mono tracks into a 2.0-channel encode, at no less than 192Kbps

With regard to 7.1-channel encoding, this is not possible with Dolby Digital, it's currently only possible with a 'pay-ware' Dolby Digital Plus encoding applications.

[DanDare1983]

Personally I would not recommend generating 'mono' (centre only) 1.0-channel encodings. You're better off generating two mono tracks into a 2.0-channel encode, at no less than 192Kbps

With regard to 7.1-channel encoding, this is not possible with Dolby Digital, it's currently only possible with a 'pay-ware' Dolby Digital Plus encoding applications.

Thankyou for your reply.

I have a couple of LPCM 1.0 mono tracks so how would I put into a 2.0 channel track?

Also for 7.1 atmos tracks could I just take the ac3 5.1 compatability track?

What is the best ac3 encoder in your opinion?

[filler56789]

Speaking in general, 128 kbps per channel
(640 kbps ÷ 5)
is the highest-quality possible for the AC-3 format.
IF the source does NOT contain frequencies above 15 kHz
(i.e., the so-called "FM quality"),
OR if you don't need them in the AC-3 (re-)encode,
then you can use 96 kbps per channel.

I have a couple of LPCM 1.0 mono tracks so how would I put into a 2.0 channel track?

You can use any audio editor, or ffmpeg, or m2s.exe,
for converting mono to stereo.
The Dolby-licensed encoders work with mono inputs,
so your mono tracks would not be a problem.:)

[DanDare1983]

Speaking in general, 128 kbps per channel
(640 kbps ÷ 5)
is the highest-quality possible for the AC-3 format.
IF the source does NOT contain frequencies above 15 kHz
(i.e., the so-called "FM quality"),
OR if you don't need them in the AC-3 (re-)encode,
then you can use 96 kbps per channel.



You can use any audio editor, or ffmpeg, or m2s.exe,
for converting mono to stereo.
The Dolby-licensed encoders work with mono inputs,
so your mono tracks would not be a problem.:)

OK thankyou for elaborating, I will go with 128 kbps per channel. Do I encode from the DTS-HD MA or from the DTS track as theirs two tracks?

[SeeMoreDigital]

Also for 7.1 atmos tracks could I just take the ac3 5.1 compatability track? Just so you know... With regard to Atmos sources. If they are from an 4K UHD Blu-ray disc, it should be possible to extract the 640kbps 5.1-channel Dolby Digital 'core' from the (Dolby TrueHD) Atmos audio stream.

[Balling]

Just so you know... With regard to Atmos sources. If they are from an 4K UHD Blu-ray disc, it should be possible to extract the 640kbps 5.1-channel Dolby Digital 'core' from the (Dolby TrueHD) Atmos audio stream.

It is in fact possible with ffmpeg. But not with tsmuxer, it extracts both thd and ac3 together.

[SeeMoreDigital]

It is in fact possible with ffmpeg. But not with tsmuxer, it extracts both thd and ac3 together.
It is possible to extract the lossy 'core' using TSmuxer (I've been doing this for years). All you have to do is select the following option: -

https://i.ibb.co/6bjnh5J/downconvert.jpg


Cheers

[Balling]

Okay.
You could do it with ffmpeg.exe -i "L:\DOLBY ATMOS DEMO DISC2016\BDMV\STREAM\00032.m2ts" -map 0:a:1 -c copy cacawe1.ac3

If you have this:

Stream #0:1[0x1100]: Audio: truehd (AC-3 / 0x332D4341), 48000 Hz, 7.1, s32 (24 bit)
Stream #0:2[0x1100]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 640 kb/s
Stream #0:3[0x1101]: Audio: eac3 (AC-3 / 0x332D4341), 48000 Hz, 7.1, fltp, 1664 kb/s

So, 0x1100 has two streams.

So yep...

The files are bitperfect. :_)