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jriker1
20th March 2012, 03:21
Title probably says most of it. I have an old movie that was created in an AVI container and has 4.0 AC3 audio. From what I understand is really old school. AC3filter nor anything else seems to support it. I can downsample to stereo but woud be loosing fidelity. Was thinking going to 5.1 would be better since none of my converters will support 4.0 format. Are there any pointers for talking 4.0 audio and converting it to 5.1?

Thanks.

JR

Midzuki
20th March 2012, 04:12
I might be wrong, but quite probably that audio stream was created incorrectly and/or muxed incorrectly and/or went corrupted somehow. Neither AC3Filter nor any decent AC-3 decoder should have any problems with a properly-generated "quadro" stream, which BTW is 100% "according-to-the-specs" :)

tebasuna51
20th March 2012, 10:48
Like Midzuki say there are no problem to play a compliant AC3 4.0.
Upload a sample (first 100KB is enough) or use LeeAudBi (http://forum.doom9.org/showthread.php?p=1522330#post1522330) to put a log.

jriker1
20th March 2012, 12:25
Like Midzuki say there are no problem to play a compliant AC3 4.0.
Upload a sample (first 100KB is enough) or use LeeAudBi (http://forum.doom9.org/showthread.php?p=1522330#post1522330) to put a log.

Thanks for the replies. I think it plays OK, it won't convert OK. Two items:


Just looking at the ac3filter settings they do not list a four channel option physically. Apparently it supports it, just not listed so thought I would mention.
Second, I am trying to use Expression Encoder 4 SP2 in order to convert to WMV for max XBOX compatibility on my windows home server. It crashes when I have the audio on 5.1 and works on 2.0/stereo. Figured if I got it to 5.1 it would be "better" with that. Also tried MP4 with the same tool and same deal.


I'll also try LeeAudBi or a sample to post when I get home unless someone thinks something else is going on based on my response.

Open to suggestions.

Thanks.

JR

sneaker_ger
20th March 2012, 16:36
Just looking at the ac3filter settings they do not list a four channel option physically. Apparently it supports it, just not listed so thought I would mention.

Mine has "AS IS (no change)", "3/1 - surround", "2/2 - quadro", "3/1+SW 4.1 Surround" etc.
Maybe the file really is broken.

jriker1
21st March 2012, 00:08
Ran it thru LeeAudBi:

Size ........: 301914368 bytes

----------------------------------------- First Frame Info
SampleRate ..................: 0 (48000 KHz)
BitRate .....................: 15 (448 Kb/s)
Version (bsid) ..............: 8 (Standard)
Bit Stream mode (bsmod) .....: 0 (main audio service: complete main, CM)
Audio coding mode (acmod) ...: 5 (3/1 - L, C, R, S)
Center Mix Level ............: 0 (0.707, -3.0 dB)
Surround Mix Level ..........: 0 (0.707, -3 dB)
Low frequency effects channel: 0 (Not present)
Dialogue normalization ......: - 28 dB
RF atenuattion ..............: 11.76 dB Frame: 1
Languaje ....................: 0 (Not present)
Audio Production Info .......: 0 (Not present)
CopyRight bit ...............: 1
Original bit ................: 1
Timecode1 ...................: 0 (Not present)
Timecode2 ...................: 0 (Not present)
Additional Bsi ..............: 0 (Not present)
Block switch flags ..........: 0
Dither flags ................: 15
Dynamic Range gain ..........: 6.01 dB Frame: 1
--------------------------------------------- Revised Info
RF Ov. Pr. min/max : -13.85 / 12.03 dB
Dyn. Range min/max : -13.85 / 6.01 dB
Total Frames ......: 168479
Duration ..........: 5391.328 seconds. ( 1 h. 29 m. 51.328 s.)
------------------------------------------------- End Info

Does the above mean this is left, center, right, and surround or sub being it says 3.1? I extracted the audio streams with eac3to and got bc.wav, C.wav, R.wav and L.wav.

In MediaInfo it shows left right center and Side Center?


Audio
ID : 1
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Codec ID : 2000
Duration : 1h 29mn
Bit rate mode : Constant
Bit rate : 448 Kbps
Channel(s) : 4 channels
Channel positions : Front: L C R, Side: C
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Compression mode : Lossy
Stream size : 288 MiB (19%)
Alignment : Aligned on interleaves
Interleave, duration : 64 ms (1.53 video frames)
Interleave, preload duration : 192 ms
Title : ass T81 3_1ch 448Kbps DELAY 0ms

Midzuki
21st March 2012, 02:52
Ooops :o , I should have remembered that, for AC3Filter, sadly the rear center channel "does not exist" :(

Still, you could give a try to:

1) valdec.exe (belongs to the AC3Filter Tools)

2) Lav Audio (or ffdshow's liba52) + Graphstudio

3) Avisynth w/ various options (uNicAudio, SoundOut, DirectShowSource, wavi.exe) :confused:

4) an up-to-date build of ffmpeg / libav :confused:

Then, you should copy the rear center channel into the "normal" back channels (i.e., Rear Left and Rear Right),
so that no information would be lost or misplaced.

jriker1
21st March 2012, 03:15
Ooops :o , I should have remembered that, for AC3Filter, sadly the rear center channel "does not exist" :(

Still, you could give a try to:

1) valdec.exe (belongs to the AC3Filter Tools)

2) Lav Audio (or ffdshow's liba52) + Graphstudio

3) Avisynth w/ various options (uNicAudio, SoundOut, DirectShowSource, wavi.exe) :confused:

4) an up-to-date build of ffmpeg / libav :confused:

Then, you should copy the rear center channel into the "normal" back channels (i.e., Rear Left and Rear Right),
so that no information would be lost or misplaced.

Thanks for the info. So is the BC.wav eac3to created then usable to duplicate as the left and right rears?

Thanks.

JR

Midzuki
21st March 2012, 04:06
Thanks for the info. So is the BC.wav eac3to created then usable to duplicate as the left and right rears?

Yes. :)

Yet another ooops :o I had read your previous post too fast :o and understood eac3to had created a 4.0 output :stupid:

Yet another ooops :o :o Actually, it seems Ac3Filter does support the 3/1 layout, BUT I am not sure (have not checked) if it can generate a correct output in this case :confused:

tebasuna51
21st March 2012, 04:34
So is the BC.wav eac3to created then usable to duplicate as the left and right rears?
Yes, but if you want preserve the volume balance you need attenuate by -3dB the new left and right rears.

jriker1
21st March 2012, 23:50
Yes, but if you want preserve the volume balance you need attenuate by -3dB the new left and right rears.

Thanks. Can you clarify how I do that? With GoldWave? Also I assume the surround center is eliminated then right? So I'll end up with 5.0 surround?

Thanks.

JR

tebasuna51
22nd March 2012, 12:01
Can you clarify how I do that? With GoldWave?
Yes, for instance.

If you are a AviSynth user I can send you a script to do the job directly from AC3 3/1.0 to AAC 5.0 or 5.1 using BeHappy/MeGUI or wavi.

Also I assume the surround center is eliminated then right? So I'll end up with 5.0 surround?
If you need 5.1 you can add a empty new channel.