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Subject:AC3 encoding normalization...
Posted by: Larkero
Date:4/8/2003 2:26:32 PM
After noticing that the volume of an AC3 encoded project was not the same as what I wanted it to be, I used a 440hz tone that I loaded in Vegas4... I loaded the 440hz tone as left front, right front, left rear and right rear... I set the mixer volumes so I read -0.1 when playing back the sounds, then I encoded the project as AC3 only to find out that the sound seem to have been normalized by at least -20db !!! Is it normal or did I missed something ??? |
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Subject:RE: AC3 encoding normalization...
Reply by: Mr_Plant
Date:4/8/2003 7:04:31 PM
I am having same problem but no-one has repsonded as yet to my question about this. Why does the AC-3 encoder lower the level of the signal you have "mastered" at in Vegas? More importantly, is there a way to change this behaviour??? Anyone?? |
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Subject:RE: AC3 encoding normalization...
Reply by: Baylo
Date:4/10/2003 1:50:15 PM
I remember reading something by SPOT once about -20db being the reference output level for broadcast. IE -20db FS is the equivalent of 0db in the analog broadcast world. Maybe that has something to do with it? Mark |
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Subject:RE: AC3 encoding normalization...
Reply by: rphtx
Date:4/10/2003 10:12:02 PM
I'm having the same prob and posted a similar ? under the dvda forum.. |
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Subject:RE: AC3 encoding normalization...
Reply by: dvddude
Date:4/14/2003 9:32:50 AM
I'm having the same problem. Funny thing is that for my menu background, I have a WAV file and let DVD-A transcode it to AC3, while all my other material I export to AC3 from Vegas. When the disc is done, the Vegas stuff is all extremely low in gain, while the menu audio BLASTS out of the speakers. So... what gives? |
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Subject:RE: AC3 encoding normalization...
Reply by: Mr_Plant
Date:4/15/2003 2:27:39 PM
To be honest, I am a bit annoyed with this now. I bought and paid for Vegas+DVD and have mastered 3 of my own DVD disks in the past few weeks. Each finished project file has been imported into DVD Architect. I totally understand how that works now and with every single project I have HAD to use PCM audio as the minute anything at all gets passed through the AC-3 encoder (I only use 2 channel stereo mode at the moment by the way - want to walk before I can run!), the results are un-usable. It lowers my audio mix's gain far too much - its almost laughable... Is ANYONE out there getting the AC-3 encoder to work at a good level of gain - if so how? Why is no-one posting to say its working fine?? I am confused! One striking example - I render my finished audio to WAV format and also to AC-3 format. I then load up each file seperately into POWERDVD - the AC-3 is unbearably low in volume. I understand DVD sound is very wide dynamically etc. but there has to be a way to set this surely. Any changes I make to the audio settings in the encoder don't seem to be audible using the test above. |
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Subject:RE: AC3 encoding normalization...
Reply by: dvddude
Date:4/16/2003 11:01:44 AM
I agree; this is a repeatable, unacceptable problem that many people seem to have, no one has an answer for it, and no one is standing up to say, "Works for me; try this..." This is very bizarre. I assume it's working for SOMEBODY, so what are the rest of us doing wrong? I notice that if I export AC3 from Vegas, the audio is almost inaudible, but if I import a WAV into DVD-A and let *it* do the compression (verifying this in the Optimize screen), the levels are loud! But I can only do this for menu music, of course, not program audio, so it's no solution, but aren't VV and DVD-A using the same AC3 DLL? If so, what is going on? Why is Vegas barfing on the levels? The only applicable setting seems to be the "dialog normalization" drop-down, and that is not solving the problem. No one has any theories/comments/hints/rebuttals? |
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Subject:RE: AC3 encoding normalization...
Reply by: swattum
Date:4/17/2003 10:19:38 AM
At the risk of being blasted - AC3 works fine for me. I do see an approx -2db reduction, but nothing like what's being reported. Here's what I've done - ripped a music video from a DVD, used DVD2AVI to extract the AC3 information and then used BeSweet to convert the AC3 into 6 wav files. These were then pulled back into Vegas along with the original video. A new AC3 was rendered from Vegas - I can't hear much difference between the original and the new. SO I took the new AC3 file produced by Vegas and ran it back thru BeSweet to again produce 6 wave files and then compared the first wav with the second wav in CoolEdit, which is where I see the approx -2db reduction (just by looking at the graph of the wav - nothing really fancy). Each track has the red dot in the appropriate speak location for that track. The track vol is at 0db and I've not messed with any of the mixer controls at all. Have any of you tried changing the dialog normalization setting for the AC3 render? |
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Subject:RE: AC3 encoding normalization...
Reply by: dvddude
Date:4/17/2003 11:29:15 AM
Yeah, the dialog normalization is about the only thing we CAN fiddle with. It sounds like you're using a 5.1 file; everything I've been doing has been using the AC3 Stereo template. I wonder if that makes a difference? I pull an AVI into Vegas, right-click the audio and choose "switches | normalize" to get nice loud audio, export the video and audio using, respectively, the MainConcept MPG-2 and AC3 Stereo templates, pull these into DVD-A, and the audio is VERY low. If I pull WAV audio into DVD-A, it sounds nice & loud! The problem is definitely happening during the Vegas export through the AC3 "filter." At least using stereo... I'm not even going to TOUCH 5.1 until I can get 2-channel working. |
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Subject:RE: AC3 encoding normalization...
Reply by: swattum
Date:4/17/2003 12:21:53 PM
My latest experiement was with 5.1, but I cannot recall having these problems with Stereo AC3 either. In fact just the other day I captured Children of Dune, pulled the files into Vegas, removed the commercials, rendered MPEG and Stereo AC3 and pulled these into DVDA; the DVD came out great (possibly one of the best I've burned yet). One thing I do find interesting with the Stereo AC3 is that my receiver insists that there are 5 channels (all 5 channel lights come on). Next time I get a chance I'll have to see if there's a way to tell what's really in the AC3 data that DVDA put on the disk - I don't think it recompressed as the DVD prep time was pretty short, but maybe it did.... Have you tried this without doing the Normalize switch on the wave file in Vegas? I've not been changing any of the switches on my wave files and things have been coming out great. Ok, an update - I just did a quick test specifically with Stereo AC3 - I selected the normalize switch on the track and rendered to AC3. Used BeSweet to create a stereo wave file from the AC3 - looked fine and db level had been increased. Pulled the AC3 into DVDA, prepared a DVD, used DVD2AVI to pull the AC3 file from the VOB and again used BeSweet to extract a stereo wave file - no change in db. So this appears to be working fine for me; I can't explain why you are seeing the results you are seeing. |
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Subject:RE: AC3 encoding normalization...
Reply by: dvddude
Date:4/17/2003 3:57:47 PM
It's good to hear that someone is having good luck. I'm stumped. I too notice that my receiver gets fooled by the stereo AC3 signal. My DVD player says "Dolby 2-channel" but the receiver thinks it's 5.1. I only recently started using the "normalize" switch; the gain issue was there before I started using it, and in fact compensstaing for gain loss is one of the reasons I went looking for a normalizing function. This is really, really bizarre. |
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Subject:RE: AC3 encoding normalization...
Reply by: MarkWWW
Date:4/18/2003 6:40:54 AM
Try setting the "Dialog normalization" level to -31dB and changing the "Dynamic range compression: Line mode profile" to None and doing another test render. That may achieve what you are after. |
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Subject:RE: AC3 encoding normalization...
Reply by: Sunray
Date:4/18/2003 1:48:13 PM
That's exactly what I would recommend. Rather, with AC-3 encoding, what you hear is not always what you'll get. There are a number of factors in the encoding process, including dynamic range compression, dialog normalization, surround/center channel mix levels, gates, etc which can alter the playback of your encoded material. Another factor is the decoder on which your material is being reviewed. You really need to tweak the encoder settings based on the qualities of your source material, and the expected audience. For some good info on doing Dolby encoding, check out: Dolby Digital Professional Encoding Guidelines http://www.dolby.com/tech/L.mn.0002.DDPEG1.pdf I'm not sure why you would be experiencing a difference in attenuation between rendered from Vegas vs DVD Architect. I'll check it out, but perhaps it has to do with which rendering templates are being used. -pj |
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Subject:RE: AC3 encoding normalization...
Reply by: Larkero
Date:4/19/2003 10:37:41 AM
Thanks much for the infos Sunray... Much apreciated... |
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Subject:RE: AC3 encoding normalization...
Reply by: Larkero
Date:4/19/2003 10:38:18 AM
Thanks for infos Mark... |
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Subject:RE: AC3 encoding normalization...
Reply by: Larkero
Date:4/20/2003 10:32:56 AM
ok... Been doing some tests with the following settings: Dialog Normalization set to -31db Dynamic Range Compression and RF Mode Profile set to None... The rendered AC3 file seemed a bit strange when played with WinDVD from the HD... The output was a LOT better than before BUT... for some unknown reasons, the sound keeps going up and down !!! Ex: The intro of the original Soundtrack in V4 is smooth for about 20 seconds then comes the Hardbeat... When the rendered AC3 file is played back with WinDVD, the intro is loud but when comes the Hardbeat, everything drops down as if there was somekind of "Gating" effect occuring... Any ideas on why this thing happens ??? Thanks for your time, ;-) |
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Subject:RE: AC3 encoding normalization...
Reply by: Mr_Plant
Date:4/21/2003 7:07:44 PM
Thanks everyone. Good to get some feedback from people on this - Checking out the recommendations! |
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Subject:RE: AC3 encoding normalization...
Reply by: edmellnik
Date:4/22/2003 1:01:32 AM
I cant figure out where Sonic is... Why arent they here trying to help us? Many fo us have been fighting with AC-3 and 5.1 and I have not figured out where the company is. In the NEWTEK forums they are people from the company there to help and get back to you within the hour. TOO bad.... The alledged free three months of teck support is not much good since they dont answer there phone. I have been trying to figure out why my 5.1 shows 5.1 for the moving menu but only shows prologic when a chapter is choosen. Also, I get reverb on everything unless I switch the receiver to just stereo. I also looks like there are many default settings that load plug ins and effects you may not want. I guess you have to just learn how to turn them all off. |
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Subject:RE: AC3 encoding normalization...
Reply by: studioman3000
Date:5/16/2003 6:54:02 AM
I've been wondering about the up/down limiting thing. Some of my music tracks are very dynamic, and only in stereo. And when the soft tracks come up to the "normal" level, the noise floor is outrageous. Then when something "louder" comes in, it drops down. Like the attack and release on the compression is set to about 1/2 second. So it's really annoying. I have yet to adjust any setting, though. But I've had no problems other than this. Thanks, Sunray, for the link - I hope it proves useful. I'll post any useful info. |
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Subject:RE: AC3 encoding normalization...
Reply by: way2slo
Date:5/16/2003 7:11:53 PM
i have tried what MarkWWW mentioned as above. now i found another problem. playing a dvd in my player, the level is too hot compared to commercial dvd. any thought? what should be the setting? |
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Subject:RE: AC3 encoding normalization...
Reply by: MarkWWW
Date:5/17/2003 7:04:23 AM
My suggestions in that message were purely intended as a response to what I believed the original questioner was after - how to get the maximum level from his AC-3 encoded material. I did not intend anyone to think they should be used for general purposes. In order to get the best results from AC-3 encoded audio it is necessary to choose values for Dialog Normalization and Dynamic Range Compression that suit the particular characteristics of the audio in question. As I mentioned in an answer to one of your previous questions (http://www.sonicfoundry.com/forums/ShowMessage.asp?MessageID=175697&Page=0), Dolby have produced a number of documents explaining the use of these settings - have a look at "Dolby Digital Professional Encoding Guidelines" (http://www.dolby.com/tech/L.mn.0002.DDPEG1.pdf) or "All About Audio Metadata" (http://www.dolby.com/metadata/pa.in.0101.AllMetadata.pdf) or "Dolby Metadata Guide" (http://www.dolby.com/metadata/pa.st.0102.MDGuide.pdf). Most commercial DVDs will be using one of the Dynamic Range Compression profiles and you may find that by choosing one of these (e.g. Film Light or Film Standard) your AC-3 material may more closely match the characteristics of commercial DVDs when played back on your player. Alternatively, you may find that a more "normal" choice for the Dialog Normalization value may be what is required. It's not possible to give you a simple answer to the question "What should be the setting?" - which settings should be chosen depend on the characteristics of the audio in question (e.g. speech, classical music, rock music, a film soundtrack, etc, will all have different values for the average level versus maximum level characteristic that the Dialnorm parameter is intended to deal with) and how it is intended to be used (which is why a variety of DRC profiles are specified). You'll just have to choose suitable settings for your material, guided by the advice from Dolby. Mark |
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Subject:RE: AC3 encoding normalization...
Reply by: studioman3000
Date:5/25/2003 3:50:47 PM
I did some looking around in the settings like I should have before and found some helpful things. You can set the audio normalization to "FILM" or "AUDIO" or a couple other things. I am currently experimenting to see how it turns out. |
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Subject:RE: AC3 encoding normalization...
Reply by: studioman3000
Date:5/25/2003 4:55:01 PM
The nice thing about this .pdf file: http://www.dolby.com/tech/L.mn.0002.DDPEG1.pdf is that it talks about all kind of options for compression and normalization that don't exist when we're rendering in VV4.0. What the hell? |
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Subject:RE: AC3 encoding normalization...
Reply by: thrillcat
Date:6/8/2003 9:48:05 PM
The compression setting you're fiddling with isn't a "file size" type compression, but an audio compressor, which is meant to do exactly what you're explaining. It brings the low level audio up to a higher level, and when the soundtrack gets loud, it crushes the peaks to keep it from distorting, or, in the digital audio world, disappearing. So, the more compression you're applying, the higher it's bringing your low level audio (and your noise floor), and the more it's crushing the peaks. And, as you've found, ruining any dynamic range you may have mixed for. |
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Subject:Maybe I;m missing something but...
Reply by: dvdude
Date:6/12/2003 12:04:03 PM
...as far as I can tell, the AC-3 encoder seems to be working fine (for me at least). I agree that when previewing a DVD-A project that uses AC-3, the audio is substantially lower on the computer than the PCM soundtrack. But then, it's now a dolby encoded signal. I for one don't have hardware DD decoding on my PC. However, if I go ahead and actually burn the disc, the resulting DVD correctly puts my receiver into dolby digital mode. I created a test disc with a single video object and both PCM and AC-3 Stereo soundtracks. Playing the PCM version followed by the AC-3 version, the audio levels are just about identical. This is despite leaving the default normalization setting at -27db in both the encoder (VV4) and DVD-A apps. So I just came to the conclusion that preview doesn't perform AC-3 decoding. What's the problem again? Andy |
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Subject:RE: AC3 encoding normalization...
Reply by: wilsondr
Date:6/23/2003 2:49:29 PM
I posted a guide on another site that explains the methods you need to use to properly encode audio with AC3. http://forum.doom9.org/showthread.php?s=&threadid=56020 |
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Subject:RE: AC3 encoding normalization...
Reply by: thrillcat
Date:7/12/2003 12:03:41 PM
Thanks for that post wilsondr...very helpful. I wasn't having any real "problems" with encoding, but I now know what those settings actually do, and understand why they are set where they are. You can always learn more... |