Compliant AC3 Encoding

[Teariz]

Hey guys, I'm sort of a n00b to the DVD authoring scene, but I've put together a couple of DVDs now, and I notice that they play just fine on most players, including my XBox. But on our pride and joy, the surround sound dvd player, it glitches every so often on the sound. It's a coby player, and I've read in a lot of guides that the tools I'm using don't output 100% compliant ac3 fiels (right now I'm using: ffmpeg -hq -i input.wav -ab -128 -ar 48000 output.ac3 -- but I've also heard the same is true of besweet)

Are there any better free AC3 encoders avilable? Command line based is an option, I have no problems using the command line. (Actually I prefer it for batch encodes...) What freeware AC3 encoders are avilable peroid, besides besweet and ffmpeg?

(also -- I've also heard that tmpgenc does a great job, but it's not free, so I can't use it.)

[SimonSez07]

all the free ac3 encoders that i have ever seen are based on ac3enc.dll which is from the ffmpeg project. the only other way to get an encoder without paying lots of money is to try downloading a free trial of software that comes packaged with ac3 encoder.

example: intervideo dvd copy 4

after you install the trial, you can use graphedit and encode with the iviaenc.ax filter. no cli (unfortunately) but the audio encoding engine does not expire with the trail : )

im sure there are other trial software with encoders like this. you can also look at cheap products like those from xilisoft and pegasys-inc

NeroVision Express (free trial) comes with build-in AC-3 encoding, but i dont know how to encode audio without encoding video also, which is very slow. the only way i have been able to encode wav to ac3 is to create avisynth script with dummy video also. then demux ac3 from resulting file.

[Teariz]

That's odd to hear, and I wonder if you could confirm if any of the following is acurate information: (they are posts in another thread, on another forumn the url is:
http://club.cdfreaks.com/showthread.php?t=83723 )

Monkey #1: .....AC3enc is commercial and no longer produced.....
....Besweet would be fine for the job. You could also use AC3Machine as it's got a very simple interface for the job......AC3enc does create a more compliant file but I've never had any issues personally and using AC3enc is a longer process.

Monkey #2: I think ffmpeg does this, it's a freebee and is much more reliable than BeSweet.

Monkey #3: BeSweet no longer outputs AC3, because put simply it never worked properly. Not sure if ffmpeg suffers from the same compatibility issues, but from what I hear the quality is not that great.

-- Confused because everyone has a different opinion on what is what, and aparently ac3enc.dll is not free, but somehow the free software I downloaded contains it? --

[Mr. Monte]

Well I just D/L Besweet beta 1.5 and BeSweetGUI nad encoded a MP3 into a AC3...it worked..it's available..however..it's sound quality was not what I had hoped.

[Teariz]

I've tried besweet and ffmpeg, like I said it works in all my players but the good one. :-( -- It could be a copy protection deal that the good one has and the other's don't (a really wierd one, anyway?) on the other hand it could just be that it only supports fully compliant ac3, and if I have a way to generate a fully compliant ac3 file I can test that theory.

What other audio formats are supported besides ac3 and raw pcm? I heard mp2, but I don't know if that's acurate... maybe I should just author dvd's with another type of sound file? Dunno.

Also something that is irritating me, is that sometimes the .ac3 files that I create (depends on the source type...) come out with really low volume levels -- but that's in the sticky subject, and I need to research that some more before I post any already answered questions out of ignorance, and besides -- it's off-topic to this thread.

[Mr. Monte]

I thought I read that MP2 is only supported for PAL and that AC3 is supported for NTSC. The low volume issue..sis you click the boost box in BeSweetGUI?

[SimonSez07]

ok, just to clear up a few things

@Teariz - about those quotes:

1) there was an AC3enc (ac3enc.exe) that was commercial and is no longer produced. it was the ac3 encoder for Scenarist v2.x; i think it has since been replaced by Sonic Foundry Soft Encode.

2) yes, although they are based on the same core encoder ffmpeg may be less buggy than besweet.

3) yes, the latest beta of besweet (1.5b31) does contain ac3enc but the latest stable (1.4) does not. as to weather ffmpeg suffers incompatability also, i do believe so; again they are based on the same core and yes, the quality is supposedly not great


the ac3enc.dll included in BeSweet is:
"AC3enc.dll v1.20 (Feb 18 04) by Fabrice Bellard http://ffmpeg.org"

the ac3enc.dll included in HeadAC3he v0.25 alpha 3 is a ver 1.00 and may be a custom compiled version of the ffmpeg source, im not sure. download HeadAC3he_0.25a3.rar from doom9's german forum here (http://forum.gleitz.info/showpost.php?p=228663&postcount=270) (rar password is "nodelay")

also, i have experienced this low volume with several ac3 encoders also (except intervideo encoder), it has something to do with dolby's gain settings you can read about here (http://forum.doom9.org/showthread.php?t=56020)

as for alternative encoders that may be more compliant, i suggest to try iviaenc.ax with graphedit (very easy and fast) or nero (free trial). for the latter you must create an avisynth script that contains your audio.

example:
audio = WavSource("audio.wav")
video = BlankClip(length=int(Audiolength(audio)/Audiorate(audio)*29.97), width=720, height=480, fps=29.97)
AudioDub(video, audio)

you can encode using nerovision express (very slow), and demux ac3 using tmpgenc 2.5; although there MUST be an easier way to use nero to encode ac3!

[Mr. Monte]

Simonsez,

Thanks for the info. I have a question. The guide written over at Video Help says that the resulting audio needs to be at 48000 HZ to be DVD compliant. I don;t see a 48000 option on the HeadAC3 you posted a link for. Would that mean producing a AC3 audio file with 44100 would not work if imported into a DVD menu?

[SimonSez07]

dvd audio MUST be 48000 hz. the "resample" option is for if you wish to change from 48000hz to a lower sample rate. it is assumed that your audio is already 48000 hz before using headac3he. if you wish your output to be dvd-compliant DO NOT choose resample option.

if your audio is LESS THAN 48000 hz, then you must use another tool to upsample.

[SimonSez07]

---------UPDATE:
the only file necessary from intervideo to encode ac3 in graphedit is: iviaenc.ax but you must register it (regsvr32 iviaenc.ax) and enter this into the registry:

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\GPI\Settings]
"Ctrl4Y"="6B5GB31F93901OHU6J7NVPHBAU8N1OIU73HNNPI88IBN95O"
"Ctrl4Y_1"="84D0SEM3VMEC6A3U1R9E135E81HM0F6FUICKUT8O4IUFH6O"
"Ctrl4Y_2"="66KCLHL3LALQ1MCEIJJO52CEG7PVD3KCVNHP144GRNFS9GO"
"CtrlA2_AE"="02D39JG"
"CtrlY4"="63CH6TG"
"CtrlY4_AE"="63CH6TG"
"CtrlZ"="8KOJADAF8OR3SJAF7P13OGHQ891IAM2M"
"CtrlZ_1"="8PN7UEDKJMCR6A023N4UV0T7BO1HI86H"
"CtrlZ2"="6B5GB3PF9F90149U6J7NVPHB8JGNH1H49BG09PI88IBN95O"
"CtrlZ2_1"="84D0SEM3TQ0Q0J383N1EP35E81HM0F6FUICKU70OAEUFP6O"
"CtrlZ2_2"="92KCLHL3LALQ1MCEIRJO12CEI7PVD3KCVNUUPPKIQJAT5HG"

the file is available for free from intervideo as part of dvd copy trial download (http://a1394.g.akamai.net/7/1394/3235/v001/webdownload2.intervideo.com/intervideodvdcopy4/release2/Enu/IVIDVDCopy4.exe) (50+ MB) or here (http://www.geocities.com/simonsez07/iviaenc.zip) is the filter seperately.

this is fast, free and does *not* create low-volume ac3's. i dont know how compliant it is compared to other encoders, and i dont think you can set advanced parameters like Dialog Normalization, but it works for me.

[bobcat56458]

SimonSez07: Thanks for the download link. I’m able to encode a Dolby Digital 2.0 stereo AC3 file with the InterVideo encoder, and GraphEdit. Has anyone been able to get it to encode a DD5.1 surround file, as I don't see this option in the InterVideo Audio Encoder Properties?