Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > General > Audio encoding

Reply
 
Thread Tools Search this Thread Display Modes
Old 4th July 2019, 03:11   #1  |  Link
orion44
None
 
orion44's Avatar
 
Join Date: Jul 2007
Location: The Background
Posts: 190
Minimum suitable bitrate for 5.1 AC3 audio?

What would be the minimum suitable bitrate for 5.1 AC3 audio?

Is 384 kbps good enough for 5.1 AC3 audio?
orion44 is offline   Reply With Quote
Old 4th July 2019, 08:32   #2  |  Link
Blue_MiSfit
Derek Prestegard IRL
 
Blue_MiSfit's Avatar
 
Join Date: Nov 2003
Location: Los Angeles
Posts: 5,557
It's "good enough" but it's not fully transparent. 384 Kbps will still lowpass filter a lot of stuff out.

If you're using AC3, I say spend the full 640 Kbps. If you must save some space, 448 is a good compromise, and was often used on DVD. 384 is the minimum to get decent quality.
Blue_MiSfit is offline   Reply With Quote
Old 5th July 2019, 10:28   #3  |  Link
SeeMoreDigital
Life looks better in UHD
 
SeeMoreDigital's Avatar
 
Join Date: Jun 2003
Location: Notts, UK
Posts: 11,453
orion44,

Is there any particular reason why you need to use AC3?
__________________
| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 | My Network Layout & A/V Gear |
SeeMoreDigital is offline   Reply With Quote
Old 5th July 2019, 15:10   #4  |  Link
orion44
None
 
orion44's Avatar
 
Join Date: Jul 2007
Location: The Background
Posts: 190
Quote:
Originally Posted by SeeMoreDigital View Post
orion44,

Is there any particular reason why you need to use AC3?
Lower file size.

Last edited by orion44; 5th July 2019 at 15:22. Reason: A particular reason.
orion44 is offline   Reply With Quote
Old 5th July 2019, 16:05   #5  |  Link
mariush
Registered User
 
Join Date: Dec 2008
Posts: 590
Maybe consider AAC then, should give higher quality than AC3 and it should have wide support. VBR 256-320 kbps for 5.1 should give decent quality.

NeroAAC command line encoder can do 5.1 and MeGUI should support it : https://www.videohelp.com/software/Nero-AAC-Codec

If you don't care about playback on TVs (older), consider Opus ... it's new and open source and should give better quality than the standard AAC.
mariush is offline   Reply With Quote
Old 5th July 2019, 21:28   #6  |  Link
SeeMoreDigital
Life looks better in UHD
 
SeeMoreDigital's Avatar
 
Join Date: Jun 2003
Location: Notts, UK
Posts: 11,453
Quote:
Originally Posted by orion44 View Post
Lower file size.
Hmmmm... What's your playback device?
__________________
| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 | My Network Layout & A/V Gear |
SeeMoreDigital is offline   Reply With Quote
Old 5th July 2019, 22:10   #7  |  Link
orion44
None
 
orion44's Avatar
 
Join Date: Jul 2007
Location: The Background
Posts: 190
Quote:
Originally Posted by SeeMoreDigital View Post
Hmmmm... What's your playback device?
I only use desktop PC.
orion44 is offline   Reply With Quote
Old 5th July 2019, 22:44   #8  |  Link
mariush
Registered User
 
Join Date: Dec 2008
Posts: 590
Use Opus or AAC then...
If you have foobar2000 (music player) https://www.foobar2000.org/download you can right click on an audio file and select convert. Select Opus and choose VBR and pick your vbr bitrate...256-320 kbps for 5.1 should be perfectly acceptable.
If it asks where you have the OpusEnc executable, download the opus codec package from official website and unpack it somewhere and select the opusenc.exe file : https://archive.mozilla.org/pub/opus...2-opus-1.3.zip
mariush is offline   Reply With Quote
Old 6th July 2019, 04:28   #9  |  Link
tebasuna51
Moderator
 
tebasuna51's Avatar
 
Join Date: Feb 2005
Location: Spain
Posts: 5,643
Quote:
Originally Posted by orion44 View Post
I only use desktop PC.
If you have the audio Receiver/Amplifier 5.1 conected by HDMI to PC you can use Opus/AAC/EAC3 for your movies, with better quality/size than AC3.
The player in PC (MPC-HC, VLC,...) decode the audio and send PCM 5.1 by HDMI.

If you only have a SPDIF conexion between PC and Receiver you must remain use AC3 to preserve 5.1 channels. The player must send AC3 without decode because SPDIF only support decoded PCM stereo.
__________________
BeHappy, AviSynth audio transcoder, in Doom9 forums. NicAudio, BassAudio, audio decoders.
tebasuna51 is offline   Reply With Quote
Old 6th July 2019, 12:13   #10  |  Link
SeeMoreDigital
Life looks better in UHD
 
SeeMoreDigital's Avatar
 
Join Date: Jun 2003
Location: Notts, UK
Posts: 11,453
Quote:
Originally Posted by tebasuna51 View Post
If you only have a SPDIF conexion between PC and Receiver you must remain use AC3 to preserve 5.1 channels. The player must send AC3 without decode because SPDIF only support decoded PCM stereo.
I haven't checked recently but does Media Player Classic still offer the ability to transcode multi-channel formats such as: AAC and Opus to AC3 and pass it via SPDIF or HDMI
__________________
| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 | My Network Layout & A/V Gear |
SeeMoreDigital is offline   Reply With Quote
Old 6th July 2019, 12:15   #11  |  Link
sneaker_ger
Registered User
 
Join Date: Dec 2002
Posts: 5,495
MPC-BE's audio decoder has an option to encode to AC3. MPC-HC does not have this feature built-in but can be added via e.g. MPC-BE's filter, AC3filter, ReClock.
sneaker_ger is offline   Reply With Quote
Old 7th July 2019, 10:43   #12  |  Link
tebasuna51
Moderator
 
tebasuna51's Avatar
 
Join Date: Feb 2005
Location: Spain
Posts: 5,643
I make a mini test encoding a 5.1 to opus, aac (qaac) and eac3 (ffmpeg) at 320 Kb/s.

For me are transparent all, but using spek, I know than frequency analysis is only a part of quality mesurement, I see some differences:

- opus cut frequencies greater than 20 KHz, qaac greater than 17 KHz and ffmpeg 16 KHz.

- maybe is not important but the opus seems more "clean" than qaac

I can't obtain a exac 320 Kb/s from qaac, from 307 jump to 340, the sizes:

Code:
Pines_5.1.wav           166.920.236
Pines_5.1.wav_340.aac     8.292.039
Pines_5.1.wav_320.ac3     7.728.640
Pines_5.1.wav_320.eac3    7.728.640
Pines_5.1.wav_320.opus    7.539.904
Pines_5.1.wav_307.aac     7.488.531
The 307.aac is near 320.opus in size because the real bitrate for the opus file is 312 Kb/s

See the image: source, opus, aac
Attached Images
 
__________________
BeHappy, AviSynth audio transcoder, in Doom9 forums. NicAudio, BassAudio, audio decoders.

Last edited by tebasuna51; 7th July 2019 at 11:07. Reason: Add info
tebasuna51 is offline   Reply With Quote
Old 8th July 2019, 11:34   #13  |  Link
chros
Registered User
 
chros's Avatar
 
Join Date: Mar 2002
Posts: 1,490
Quote:
Originally Posted by tebasuna51 View Post
I make a mini test encoding a 5.1 to opus, aac (qaac) and eac3 (ffmpeg) at 320 Kb/s.

For me are transparent all, but using spek, I know than frequency analysis is only a part of quality mesurement, I see some differences:
- opus cut frequencies greater than 20 KHz, qaac greater than 17 KHz and ffmpeg 16 KHz.
- maybe is not important but the opus seems more "clean" than qaac
Interesting, thanks! Which preset did you use with qaac?
Can you also try out qaac (apple acc) with its default --tvbr 91 preset? Thanks
__________________
Ryzen 5 2600,Asus Prime b450-Plus,16GB,MSI GTX 1060 Gaming X 6GB(v385.28),Win10 LTSB 1607,MPC-BEx64+LAV+MadVR,Yamaha RX-A870,LG OLED65B8(2160p@23/24/25/29/30/50/59/60Hz)
chros is offline   Reply With Quote
Old 9th July 2019, 02:05   #14  |  Link
tebasuna51
Moderator
 
tebasuna51's Avatar
 
Join Date: Feb 2005
Location: Spain
Posts: 5,643
Quote:
Originally Posted by chros View Post
Can you also try out qaac (apple acc)
Yes this is the qaac I used, and TVBR presets are:

-V 91 Overall bitrate: 496.532kbps (cut at 18.5 KHz)
...
-V 64 Overall bitrate: 340.74kbps
-V 54 Overall bitrate: 302.205kbps

With CVBR presets:

-v 320 Overall bitrate: 342.338kbps (cut at 17 KHz)
-v 288 Overall bitrate: 307.468kbps (in the image with cut at 16.5)

Talking about cut frequency the Opus 320 Kb/s is like AC3 640 Kb/s
__________________
BeHappy, AviSynth audio transcoder, in Doom9 forums. NicAudio, BassAudio, audio decoders.

Last edited by tebasuna51; 9th July 2019 at 02:08.
tebasuna51 is offline   Reply With Quote
Old 9th July 2019, 10:04   #15  |  Link
chros
Registered User
 
chros's Avatar
 
Join Date: Mar 2002
Posts: 1,490
Quote:
Originally Posted by tebasuna51 View Post
Yes this is the qaac I used
Oh, thanks!
__________________
Ryzen 5 2600,Asus Prime b450-Plus,16GB,MSI GTX 1060 Gaming X 6GB(v385.28),Win10 LTSB 1607,MPC-BEx64+LAV+MadVR,Yamaha RX-A870,LG OLED65B8(2160p@23/24/25/29/30/50/59/60Hz)
chros is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 01:05.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.