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-   -   Producing a correct 5.1 ac3 stream using free tools? (part2) (http://www.digitalfaq.com/archives/audio/12815-producing-correct-51-a.html)

Prodater64 06-06-2005 06:17 PM

The way I can obtain ac3 audio with mencoder/mplayer is:


1 - Create a frameno.avi:

Code:

Mencoder -quiet -aid 1 -a52drc 1 -ac a52, -af format=2:float,resample=48000:0:2,channels=6:6:0:0:1:2:2:3:3:4:4:1:5:5,volume=6,delay=100:100:100:100:100:100 -channels 6 -srate 48000 -noskip -ovc frameno -oac lavc -lavcopts acodec=ac3:abitrate=384 "My.vob" -o "MyFrameno.avi
-aid: Number of audio stream. It changes related to source. This one can to be avi, vob or whatelse mencoder can manage. See docs, please.
-a52drc: Dynamic range compression level. Between 0 and 1.
,channels: As you can see, it switchs 1 to 2, 2 to 3, 3 to 4 and 4 to 1 channels. I did need that change as later, managed soundstretch with BeSweet, and in this way I obtained the correct output. I think that you don't need to switch channels for a straight test, BUT CHECK IT.
volume: in db. I think 6, duplicates volumen, as I read something about from Kwag a time ago. It can take values between -200 and 60.
delay: You need to add it for each individual channel. (I don't remember if this option works fine)

2 - Extact audio from frameno.avi:

Code:

MPlayer -quiet -ao null -vo null -benchmark -dumpaudio -dumpfile "My.ac3" "MyFrameno.avi"
Well, it is all I can say you about this thread. I don't know if from when I investigate this until now, there is any change. I hope you can test it.
It is interesting that you can manage dynamic compression and volume, isn't it.

Really it is not so tricky if you do a batch file.
Something about delay. Incredible said me once, that dvd2avi delay is related to loss of frames that this program does. But I answer him, if you process a vob straight with BeSweet, it find delay in vob file as you can see in log file. I don't know how manage mencoder that delay or if delay switch is necessary.
BTW @Inc do you foun out something about that natural delay?

incredible 06-07-2005 06:18 AM

Is it needed to do an encoding via a "noframe.avi" temporal avi container??
I remember when we had our mencoder startings where we also could only output our video only mpegs to a systemstream (mpeg) and demuxing afterwards to obtain the unique m2v.

Can't mencoder.exe safe directly the resulted/encoded AC3 bitstream into a xxxx.ac3 file ready for later usage?

AlexandreBH 06-07-2005 08:43 AM

zyphon and all:
we(me and friends here)are testing the ACDTool. this came inside audio dvd creator that is not a freeware prog but in the forum have a free download of ADCTool that convert stereo to ac3-5.1.
we still don't understand why we have to pay for dvdaudiocreator if that tool can be downloaded for free for everyone! :?
but go ahead,download it:

http://www.dvdidle.net/audiodvdcreat...opic.php?t=275

J.... (send more regards) and link to this sample (a day in the life-beatles) that he did using ADCTool from stereo cd:

http://www.jltoca.uaivip.com.br/test.ac3

Dialhot 06-07-2005 08:46 AM

5 posts in the thread you give, 2 of them are talking about volume problems :roll:

BTW : doing 5.1 from stereo ? Are you sure ?
(edit: yeah, according to the rangemeter in ac3filter the 6 channels are fully used during playback. I have to test this on my Home-theater !)

AlexandreBH 06-07-2005 09:26 AM

sure:from stereo to ac3! as we know,all to ac3 loose volume.
the hint is: normalize the stereo source before use ADCTool! see the sample.ac3 posted!

bye.

Dialhot 06-07-2005 09:40 AM

Quote:

Originally Posted by AlexandreBH
sure:from stereo to ac3! as we know,all to ac3 loose volume.

No, the volume problem related is for ac3 done from a vob (so 5.1 to 5.1).
And even for stereo to ac3 2.0 the problems exists !
http://www.dvdidle.net/audiodvdcreat...opic.php?t=129
:banghead: :banghead:
But I will see that by myself.

For mp3 -> ac3 I just verified that the total volume of the mp3 is the same as the total volume of the 6 channels produced. as you say, this is normal.

incredible 06-07-2005 12:29 PM

5.1 from Stereo??
Well this was that high treaten also at doom9. And I dont understand why.

Cause the theory is: Importing the Stereo (2ch) into a decompressor/Descrambler where the Dolby Surroundmatrix of that Stereo Stream will be used to obtain the 6 raw audio Bitstreams. Then these separate Bitstreams will be used for encoding a 5.1 Stream of it.

But thats exactly what a Surround Decoder Unit in a 5.1 DolbyDigital/Surround Receiver does. So you "take" the work of your final hardware device in your own hands by doing "ITs" preprocess on your PC by yourself. Nice, but much more bitrate according to 5.1 CH will be needed.

Or am I wrong???? :?:

The ONLY reason for doing this is IF you got a bad Surround decoding unit in your DD 5.1 Receiver. OR if you want to enter the 6 Channels "manually" by entering the dynamics using Softwarecompressors/Limiters or whatever. Indiana Jones's orig 2ch Suround sountracks (the german one o the orig DVD for example) would be a candidate for such an approach :) as it comes in bad dynamics and very low bass.

Dialhot 06-07-2005 01:35 PM

Quote:

Originally Posted by incredible
Or am I wrong???? :?:

More or less :
I said STEREO to 5.1. Not Dolby Surround to 5.1.

In fact the programm seems to implement what is done in the DSP of a DPL II amp (DPL II, not DPL).

Quote:

The ONLY reason for doing this is IF you got a bad Surround decoding unit in your DD 5.1 Receiver. OR if you want to enter the 6 Channels "manually" by entering the dynamics using Softwarecompressors/Limiters or whatever.
Absolutly not. You can just want to have somethign that is "pseudo" surround from a pure stereo stream. Exactly what is done in a DPL II DSP.

But before to conclude taht I have to test the result on my HT installation.

Zyphon 06-21-2005 12:56 PM

Hi Guys,

Sorry to ressurect this post but I noticed on D9's News page there is a new release of BeSweet Beta:

Quote:

BeSweet 1.50 beta 30 can produce Dolby Digital WAV files at arbitrary bitrates, uses soundtouch 1.3.0 and fixes a rare quality bug.

Does this mean now that BeSweet coupled with Soundtouch 1.3.0 can produce DD Way files that the volume no so low?

Forgive me being a noob in such things but I would like to know the opinions of the experts here and for any further info you guys can supply.

Thanks. :)

Boulder 06-21-2005 02:04 PM

Dolby Digital WAV is not the same as DD you use on DVDs.

Zyphon 06-21-2005 04:22 PM

Thanks for clearing that up for me Boulder. :)

Dialhot 06-21-2005 05:29 PM

I did not verify but I think this was formerly called "6 channel wav" in besweet.

Prodater64 06-21-2005 05:59 PM

Quote:

Originally Posted by Dialhot
I did not verify but I think this was formerly called "6 channel wav" in besweet.

If it is so, then you can obtain a DD ac3 5.1 from that wav.

Dialhot 06-22-2005 03:01 AM

[quote="Prodater64"]
Quote:

Originally Posted by Dialhot
If it is so, then you can obtain a DD ac3 5.1 from that wav.

Did you ever try to see if the volume problem can be avoid from this ? This can be a solution.

incredible 06-22-2005 03:24 AM

I tried it .... some time ago

Two Sources:

- a 2ch Ac3 and a 5.1 ch Ac3

both decoded using azid.dll AND also azid.exe to 2ch WAV and 6ch WAV.

those I normalized in azid and also onece I just let azid decode it and I normalized it in an Audioeditor Audition.

all these I did let encode to ac3 using ac3enc.dll.

The ac3s got recognisable less volume than the original wav.

BUT ... I dont care as all my TV broadcastings do come in send by the broadcasting station as a -3db max volume signal. 95% Of all my DVDs do got in their AC3 Volume not more then -3db peaks.

Means If I watch TV and I do switch to a reencoded DVD of mine. Theres a tiny bit less volume which I can easely compensate by adjusting the volume on my remote control.
The other case: If I do switch from the Original TV Broadcsting on my Panasonic annd my DDreceiver to a reencoded DVD INCLUDING normalized mp2 .... the Difference is like "BOOOOOM" ;)

So as 95% of my orig DVDs also arent that loud like normalized mp2's and my both Standalones do accept the streams out of the latest ac3enc.dll - I dont have any Problem.

Theres a very good german page called "EDV-Tip" where some tests on several ac3 generating engines where made. The ac3 out of the ac3enc.dll even gots more quality on very high freqs compared to softencodes encodings.
http://www.edv-tipp.de/dvd/047_dvd_sound06.htm
(Use an online translator)

The best quality seems to output Sonic Scenarist AC3Enc (not the ac3enc.dll!!!)
http://www.edv-tipp.de/dvd/047_dvd_sound08.htm

Dialhot 06-22-2005 03:50 AM

Quote:

Originally Posted by incredible
The ac3s got recognisable less volume than the original wav.

That's sucks.

Quote:

The other case: If I do switch from the Original TV Broadcsting on my Panasonic annd my DDreceiver to a reencoded DVD INCLUDING normalized mp2 .... the Difference is like "BOOOOOM" ;)
That is my problem also. I watch my DVD on a home theater system with 5 x 80 Watts. I don't mind pushing the volume up to 20 for the KDVD, but the normal setting I use is generally 12. You can imagine wht happens when I forget to get it down and swith on the radio or a CD :D

Quote:

So as 95% of my orig DVDs also arent that loud like normalized mp2's
Your ac3 decoder has a problem. I use exactly the same volume value on my amp (12) for normalized mp2 or original ac3 DVD !

Thanks for the test page.

incredible 06-22-2005 03:56 AM

Quote:

Originally Posted by Dialhot
Quote:

So as 95% of my orig DVDs also arent that loud like normalized mp2's
Your ac3 decoder has a problem. I use exactly the same volume value on my amp (12) for normalized mp2 or original ac3 DVD !

Well ... IF I do switch from orig DVDs to my encoded ones using the wav (2ch or 6ch) reencoded ac3s on these backups the volume loss is verrrry little.

My SAP is setted up to send a BITSTREAM out of the AC3s and NOT RAW audio data. So maybe some people already do have some issues on that step!? ---- and yes I have to watch out when changing from a DVD to a regular CD Audio ... the Result is a "Booooom" :D And thats also on orig DVDs

Dialhot 06-22-2005 04:42 AM

Quote:

Originally Posted by incredible
My SAP is setted up to send a BITSTREAM out of the AC3s and NOT RAW audio data.

When I'm talking about a "problem" into the decoder, I mean in the amp.
butperhaps mine is just featured with an "automatic normalizer" to handle different source level (TV/VCD/DVD/MD... they can't have all the same input level). I don't know.

Prodater64 06-22-2005 06:45 AM

Finally what to do to avoid so down sound, when we want to keep audio 5.1 at different frequency than original (448->384 for example)?

incredible 06-22-2005 06:48 AM

Do choose diff. ac3 encoders as mentioned above like softencode 5.1 or Sonics! ac3enc.exe (not ac3enc.dll).


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