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Old 13th September 2002, 17:48   #1  |  Link
Koke
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AC3 reencoding - too quiet now

Is it possible that reencoded AC3 (down to 224 kbps)
sounds too quiet. Or is it my audio setup?
I used AC3machine default settings.
Help please.
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Old 13th September 2002, 19:54   #2  |  Link
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Old 14th September 2002, 00:28   #3  |  Link
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Re: AC3 reencoding - too quiet now

Quote:
Is it possible that reencoded AC3 (down to 224 kbps)
sounds too quiet. Or is it my audio setup?
I used AC3machine default settings.
Help please
I have the same problem (the lower the bitrate, the quieter the sound), and I've tried to solve it with extra gaining, but even 12 db gain on 448 to 320 transcoding was enough only to reach 70-80% of the original volume level.

here is the log (this is 448 to 320, but when output bitrate is lower, sound is much quieter)


BeSweet v1.4RC7 by DSPguru.
--------------------------
Using azid.dll v1.8 (b825) by Midas (midas@egon.gyaloglo.hu).
Using AC3enc.dll v0.2 by Gerard Lantau & Dg (http://ffmpeg.org).

Logging start : 09/13/02 , 12:07:40.

G:\mali_programi\BeSweetv1.4RC7\BeSweet.exe -core( -input G:\Documents and Settings\XliQ Stargazer\My Documents\avi\pottie AC3 T01 3_2ch 448Kbps DELAY 0ms.ac3 -output G:\Documents and Settings\XliQ Stargazer\My Documents\avi\pottie AC3 T01 3_2ch 256Kbps DELAY 0msnew.ac3 -logfilea BeSweet.log ) -azid( -g 12db ) -ota( -d 0 ) -ac3enc( -b 320 )

[00:00:00:000] +------- BeSweet -----
[00:00:00:000] | Input : G:\Documents and Settings\XliQ Stargazer\My Documents\avi\pottie AC3 T01 3_2ch 448Kbps DELAY 0ms.ac3
[00:00:00:000] | Output: G:\Documents and Settings\XliQ Stargazer\My Documents\avi\pottie AC3 T01 3_2ch 256Kbps DELAY 0msnew.ac3
[00:00:00:000] | Floating-Point Process: No
[00:00:00:000] +-------- AZID -------
[00:00:00:000] | Total Gain: 12.0dB, Compression: None
[00:00:00:000] | LFE levels: To LR -INF, To LFE 0.0dB
[00:00:00:000] | Center mix level: BSI
[00:00:00:000] | Surround mix level: BSI
[00:00:00:000] | Dialog normalization: No
[00:00:00:000] | Rear channels filtering: No
[00:00:00:000] | Source Sample-Rate: 48.0KHz
[00:00:00:000] +------- AC3ENC ------
[00:00:00:000] | Bitrate method : CBR
[00:00:00:000] | AC3 bitrate : 320
[00:00:00:000] | Channels Mode : 5.1
[00:00:00:000] | Error Protection: Yes
[00:00:00:000] +---------------------

the rest of log file looks something like this:
...
[00:00:18.282] W7: Downmix overflow (1: +1.5dB)
[00:00:18.288] W7: Downmix overflow (1: +1.3dB)
[00:00:18.293] W7: Downmix overflow (1: +1.7dB)
....
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Old 14th September 2002, 02:56   #4  |  Link
Bobby
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Hi guys,
I fix this low volume problem by using ac3machine and enabling "Dynamic compression" @ normal, and also enabling "Auto find maximum gain".
I must add though that I've only tested this when transcoding a 5.1 ac3 track to a lower bitrate (192kbps) 2.0 ac3 track, But I'm guessing that it is the same principle's for transcoding 5.1 to lower bitrate 5.1
Hope that helps ya
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Old 14th September 2002, 03:02   #5  |  Link
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in fact, i've noticed that property of ac3enc too.
i believe i can change that, but it will take me some time. i'm now working on other stuff..
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Old 14th September 2002, 11:40   #6  |  Link
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I also noticed this behaviour on a re-encode from 448kbit 5.1 to 320kbit 5.1 - in the end I was using azid's auto-find max. gain and normal dynamic compression, but I think it resulted in some distortions in various scenes (I don't trust the azid auto-gain anyways, it always seems to distort the sound - is that possible?)
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Old 15th September 2002, 01:53   #7  |  Link
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Quote:
*Originally posted by Bobby *
Hi guys,
I fix this low volume problem by using ac3machine and enabling "Dynamic compression" @ normal, and also enabling "Auto find maximum gain".
I don't like "Dynamic compression" or any sort of compressors that reduce dynamic range, but i tried "Auto find.." and it seems that it really _only_ search maximum gain and not apply it.

Quote:

I must add though that I've only tested this when transcoding a 5.1 ac3 track to a lower bitrate (192kbps) 2.0 ac3 track, But I'm guessing that it is the same principle's for transcoding 5.1 to lower bitrate 5.1
Hope that helps ya
No, it's not the same principle because 2 channel 192 kbps audio is not so low bitrate (96 kbps/channel) , and in 448 5.1 you have 448/6=74.6 per channel which is lower bitrate than yours used in 2.0 ac3 track...
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Old 15th September 2002, 02:16   #8  |  Link
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maximal gain is being applied (you can simply test it by not using '-g max'), the issue belongs to ac3enc.dll. i even sorta find it in the source-code, but i don't have the time to fix it currently.
DRC, Gain, Normalize and other methods are always relevant, but in this case there's a more basic problem.
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Old 20th September 2002, 11:31   #9  |  Link
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I turn every feature off and just do a straight transcode, otherwise I too have heard the distortions. Glad to hear the low volume issue was tracked down.

To avoid distortion and/or artifacts my command line usually looks like-

"C:\Program Files\BeSweetv1.4RC8\BeSweet.exe" -core( -input "d:\false AC3 T01 3_2ch 448Kbps DELAY 0ms.ac3" -output "z:\false_256kbps.ac3" -logfile "C:\BeSweet.log" ) -azid( --maximize ) -ac3enc( -b 256 ) -profile( ~~~~~ Default Profile ~~~~~ )
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Old 17th November 2002, 05:56   #10  |  Link
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I've got this same low volume problem. I downsampled a 5.1 channel to 224 or 256 using default settings in AC3machine and the resulting volume is much lower, almost inaudible when played at the same volume as the original.
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Old 19th November 2002, 03:52   #11  |  Link
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Hello ^^
For the first time last night i used AC3Machine to create a 5.1 ac3 448, down to 256 5.1..i hadn't done anything like it before (Using AC3's and all in AVI's) after testing out the sound by putting it into the avi, indeed it was extremely quiet! I followed the doom9 guide on this, and even used the original audio just to check and that was at a decent volume, still a little quiet, but i find DVD's tend to be a little on the quiet side anyhow

Anyhow, i know that you said it was a problem with azid (I think that was it) and this post was started a couple of months back, has there been some kind of "Fix" since this time that i have been unable to find?

Any advice would be great! If i can't do it i might as well do the usual MP3's i always do
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Old 19th November 2002, 04:01   #12  |  Link
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Quote:
Originally posted by knight_inferno
has there been some kind of "Fix" since this time that i have been unable to find?
AFAIK the problem still exists somewhat, one movie I did last week required me to crank my amp almost all the way up just to hear the dialog. However, some moves re-encode with better loudness/gain for some reason. Then you have my extreme case from last week where it seemed I had lost almost 50% of the original volume
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Old 19th November 2002, 17:07   #13  |  Link
quantum
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My fix for this was to use Softencode to perform the downsampling following an older guide posted here. It may be slower, but the resulting AC3 file has the same volume.

I can't help wondering, if the volume is wrong with the ac3machine/besweet technique, are there other problems that are not so obvious?
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Old 21st November 2002, 21:50   #14  |  Link
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After seeing this thread, I compared some trasncoded AC3 tracks I'd done. Tracks I have transcoded from 192kbps Dolby 2.0 to 80 or 96kbps stereo are actually louder. Not many of them are very significantly louder, but they're definitely louder.

I use AC3Machine 0.41 & BeSweetv1.4 to transcode the audio for director's commentary and special features when ripping DVD -> DVD-R. I always leave the main Dolby Digital 5.1 audio track as is, so maybe the quietness people are experiencing is because of the 5.1 -> 2.0 downmix. My settings are usually:

Channels Mode: stereo
Dynamic Compression: normal
Auto Find Maximum Gain: ON
Bitrate: 80 for commentary, 96 for special features

I leave everything else at the default settings. The only problem I've noticed is that if I try to set the bitrate lower than 80, BeSweet gives me a lot of errors while transcoding.
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Old 25th November 2002, 09:37   #15  |  Link
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Quote:
I fix this low volume problem by using ac3machine and enabling "Dynamic compression" @ normal, and also enabling "Auto find maximum gain".
@Bobby
I must agree with you that this is the solution for solving that problem. I've made my own tests and ONLY when using DC@normal and azid autofind max gain, the results are ok. In all other cases the sound is MUCH quieter. I've used for my test BeSweet 1.5b6 and AC3 from Shrek.

@DSPGuru
I'm watching @ that thread from more than 2 months, and I still waiting for expert advice from you - which settings are really right to get maximum possible quality, and if there is a bug when it will be fixed (and where actually is the bug - in BeSweet or in ac3enc.dll).

@all
I agree with quantum that for now the best result which can be given is with Softencode. If someone wondering where to get this fine software (Sonic Foundry discontinued offering it) here is the link:
link to warez removed
But for christ sake its damn slow

And there is something strange I've noticed. When I reencode Shrek AC3 with Softencode, and then load reencoded or original AC3 track back, there are stream settings of the track which are same for both:
Dialog normalization: -27dB
Surround mix: -3dB
Center mix: -3dB
Ofcourse you can set these params when reencoding, and the result is just what u r setting, and I prefer to save original parameters

BUT if I load reencoded with BeSweet Shrek AC3 track I see that stream settings are changed:
Dialog normalization: -31dB
Surround mix: -6dB
Center mix: -4.5dB
That result is no matter what settings u use in BeSweet (for example I've tried to change them in azid, but the result is always the same

I think DSPGuru is the only one here which can explain that strange phenomenon

And I must say that I cant find difference using my own ear between track reencoded in Softencode, and the same track reencoded in BeSweet(using normal DC, auto find max gain and hybridgain).
Thats y i'm asking all of u do u know some program where i can load them both and compare them graphically (Sonic Foundry 5.0b for example cant open AC3 at all)

And ofcourse if U think my english is bad, dont be angry ... nevertheless I'm from Bulgaria
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Last edited by DSPguru; 25th November 2002 at 18:56.
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Old 25th November 2002, 19:01   #16  |  Link
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1. sorry guys, i'm too busy to currently work on this.
2. there is no bug with BeSweet.exe
3. true, ac3enc's Dialog normalization,Surround mix,Center mix values are static and never changes. (currently!)

Quote:
Originally posted by DSPguru
the issue belongs to ac3enc.dll. i even sorta find it in the source-code, but i don't have the time to fix it currently.
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Old 30th November 2002, 09:42   #17  |  Link
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Well, since yesterday (29.11.02) there is a new BeSweet release- 1.5b8.
And guess what ... there is new ac3enc.dll in it!
I pray that finally DSPGuru fix it
I'll give it an immediate try and inform you about results.

Also about removing link to Sonic Foundry Soft Encode as warez link, I think that this is DSPGuru last decision right and I'm not going to debate it.
But for myself I cant identify dvd.box as warez site. All the programs you can see there are freeware, and if you look at theirs first page there is poll especially asking for if you want to see shareware programs in the future.
And especially for Soft Encode, Sonic Foundry no longer support it and no longer even offer it. Here is the link you can see this:
http://www.sonicfoundry.com/Products...uct.asp?PID=12

I'm not a licensing guru, but in my oppinion when you refuse your own children, they become noones, and thus everyone owns.
The other example is with MS Dos. They no longer support it or sell it and thus owning it is not a crime.
Am I not right?
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Old 30th November 2002, 13:35   #18  |  Link
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the new ac3enc.dll is just a faster compile. that's all
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Old 13th December 2002, 01:14   #19  |  Link
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It's been 4 months and this problem is still unsolved, so there's my question: DSPguru are you able to fix this problem or not?

"(...) the issue belongs to ac3enc.dll. i even sorta find it in the source-code, but i don't have the time to fix it currently.
DRC, Gain, Normalize and other methods are always relevant, but in this case there's a more basic problem."

If it's a "basic problem" then please solve it finally because many ppl are waiting for solution.
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Old 13th December 2002, 01:58   #20  |  Link
MaTTeR
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No need to be demanding, Dg's free time is obviously limited. Someone already pointed out a working solution above which is to use Sonic Foundry's Soft Encode. It work's great but only slower than BeSweet
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