Recording AC3 sound

[Nelson37]

There is no joy in Mudville, but I'm still swinging.

Get CRC and frame size errors when I try to convert. Captured 44, 48, stereo, mono, now using Interlink Digital Audio cable, tried both from DVD and Cable. Mono at 48 seems closest.

A thread on Doom9 suggested I should be hearing a continous white noise rather than the pulsing static I get, though some here have stated they have converted such a file.

I got WinDVD and a valid AC-3 file, which I can convert and it works, and I can play the original as well in WINDVD. Playing the AC-3 in other player gives me similar pulsing static as my captures. WinDVD says captured wav is unsupported file format.

[BJ_M]

couple of points - proper reconizing and further proccessing of the ac3 file (even withthe wrong header seems to only work with the ac3 file parser found in windvd -- now you dont have to have windvd install but have someone send you "iviaudio.ax" file and manually register it

regsvr32 "C:\<location of file>\iviaudio.ax"

and unreg any other ac3 codecs installed

regsvr32 /u <name of file>

the above may not always be true -- perhaps other ac3 codecs may work .. but this one did for me ..

Check your .ac3 with softencode, if it has a bad frame or header , you can either fix it with softencode or not .. some i couldnt ...


also - when i create a ac3 file on my hardware encoder i burn time code into the file -- when i listen to it it sounds like white noise ...

scenarist ac3 enocder does not burn time code ..
also some software encoders i have checked seem to to weird things to the frame rate but thats a different subject.

when i listen to a ac3 stream without timecode it sounds more pulsing noise
(both sound like crap and shouldnt sound like REAL sound track) ...

i am rather suprised the new besweet has 5:1 encoding as it requires a lic for ac3 sound tracks .. and the enocding is not public domain .. but all the power to them i guess.

[Nelson37]

If I set my Cable box to Surround, rather than Digital Surround, and cap with Total Recorder at 48K, 16-bit mono PCM, this appears to be a valid Surround WAV file. SoftEncode accepts it, WinDVD plays the resulting AC-3 file, and it seems to have correct channel seperation.

This only works on programs listed as having Surround Sound, and using the SPDIF connector.

Next step is to synch Audio cap with Video, break down the file with Besweet or Headac3che, and then create a Prologic 2 file for SVCD and CVD.

Anybody know of a BROADCAST example which shows obvious channel seperation which I could use to test with? I get Digital Audio only on stations over channel 100 (Time-Warner) so standard network TV is no good.

Both my DVD and Cable box appear to have both modes, am I correct that the boxes are giving me a DECODED ac-3 in the form of a PCM file?
If so, what is the purpose of keeping the sound as encoded AC-3? Or is it just a simplicity of connection thing?

[Nelson37]

Interesting update - Definite confirmation that the previous Cable box, same Motorola model, WITHOUT an SPDIF did NOT do any AC3 to Prologic conversion (Prologic switched on at Receiver sounded like shit).

The new box, same Motorola model, WITH SPDIF, DOES do an AC3 to Prologic conversion - Playback is equivalent to DVD Prologic sample disk, which is what got me started on this.

So all I have to do is retain old method of capture and convert with Toolame and the Prologic encoding will be retained!

The AC3 cap will be useful when I eventually get a DVD burner, though!

Question for SoftEncode users - If it identifies my file as a 3/2 full channel file, is that definite confirmation that it is an AC3 or could it be a Prologic 2, and is there really that much difference?

[BJ_M]

...........
Question for SoftEncode users - If it identifies my file as a 3/2 full channel file, is that definite confirmation that it is an AC3 or could it be a Prologic 2, and is there really that much difference?

3/2 full channel file = dolby digital - not prologic ... so you are correct ..

[doctor15]

Glad you found that out, Nelson.

I'm still trying to work on mine. I have what appears to be a valid ac3 file by softencode, but when I downconvert it, I still just get clicks and static. I think its because it doesnt have an ac3 header.

I'm working on how to play the ac3 file as it is, to see if I really have sound. For some reason I cant play ac3 movies anymore, probably related to going to the old sound blaster drivers. As soon as I get that working i'll report back if it plays.

Right now all my ac3 movies play on my reciever as PL2, which is strange. Im not sure what is downconverting the sound.

[JDI]

Hi I have the SB Live Value but I dont have the Digital/Optical I/O card though I was looking at it for a solution to capture AC3 from stand-alone dvd player.

You say this works , yet I see others say they only get uncompressed PCM.

Can someone clear me up on this as I am considering buying the add-on Digital I/O card.

Thanks

JJ

[Nelson37]

Haven't worked on this for a while, but do have some new info.

There is a thread on Doom9 where a guy is apparently successfully capping and using AC-3, but he has a $500.00 sound card which does "bit-accurate capturing". He reports that the captured file is pure white noise, no pulsing.

Other info that the AC-3 stream has regular blocks of data and "filler", I am wondering if the pulsing means we are dropping the filler, or the other way around and dropping the data blocks. At least in the first case, there may be a software solution to "correct" the file.

I have a downloaded AC-3 which plays in WinDVD, but in other software sounds same as files I capture. I have never been able to play a captured file, however. But it does seem as though it is similar enough that there should be some work-around.

[JDI]

Ok thanks for the info.

[JDI]

Hi I just contacted Creative support and they told me that even with a SB Audigy and the Digital I/O card I would not be able to capture AC3. I see some who own sblive have done it.......how I don't know. Creative told me I would need a more advanced sound card. I looked at M-Audio and Terratec DMX 6Fire 24/96 / 6Fire LT. Excellent cards but price is steep. I also see the new Aureon Sky 5.1 by terratec , looks good ......I live in Canada so easy access to one of those cards is not immediate. Can anyone give a good 5.1 sound solution that can cap 1:1 which doesn't break your wallet??

Thanks for your time.


JJ