AC3 to WAV?

[killerteengohan]

I have a DVD that I wish to sync the audio to the Japanese DVD I have because the video on it is better looking. Problem is, the program I sync with cannot work with .AC3 files.

Will saving the .AC3 audio track as a .WAV file for editing cause quality loss in the .WAV file? I was under the impression that .WAV is a lossless format which shouldn't reduce it any further than the original .AC3 already has been, but I want to be sure.

I just wondered because the AC3 and the WAV files wave pattern look very slightly different in places. I doubt audibly noticeable but I can see it visually.

I know .AC3 is lossy to begin with and I am aware saving again from .WAV to something else lossy will reduce it a bit but I am concerned about the .WAV and might keep it that way.
No I do not wish to change audio editing software to something else so please do not suggest it. I would just like my initial question answered.

[newpball]

Will saving the .AC3 audio track as a .WAV file for editing cause quality loss in the .WAV file? I was under the impression that .WAV is a lossless format which shouldn't reduce it any further than the original .AC3 already has been, but I want to be sure.

What you write is true, but are you going to keep it lossless? If not you will lose quality.

[killerteengohan]

Will saving the .AC3 audio track as a .WAV file for editing cause quality loss in the .WAV file? I was under the impression that .WAV is a lossless format which shouldn't reduce it any further than the original .AC3 already has been, but I want to be sure.

What you write is true, but are you going to keep it lossless? If not you will lose quality.

I was going to save the .AC3 as . AAC so saving the .WAV as .AAC should end up the same then if what I said is true. Correct?

[-Habanero-]

I have a DVD that I wish to sync the audio to the Japanese DVD I have because the video on it is better looking. Problem is, the program I sync with cannot work with .AC3 files.

Will saving the .AC3 audio track as a .WAV file for editing cause quality loss in the .WAV file? I was under the impression that .WAV is a lossless format which shouldn't reduce it any further than the original .AC3 already has been, but I want to be sure.

I just wondered because the AC3 and the WAV files wave pattern look very slightly different in places. I doubt audibly noticeable but I can see it visually.

I know .AC3 is lossy to begin with and I am aware saving again from .WAV to something else lossy will reduce it a bit but I am concerned about the .WAV and might keep it that way.
No I do not wish to change audio editing software to something else so please do not suggest it. I would just like my initial question answered.

Use blacksunsoft's ac3tool to convert to WAV.

[newpball]

Will saving the .AC3 audio track as a .WAV file for editing cause quality loss in the .WAV file? I was under the impression that .WAV is a lossless format which shouldn't reduce it any further than the original .AC3 already has been, but I want to be sure.

What you write is true, but are you going to keep it lossless? If not you will lose quality.

I was going to save the .AC3 as . AAC so saving the .WAV as .AAC should end up the same then if what I said is true. Correct?

Yes, unless the codec is smart (which they seldom are).

[Cornucopia]

Has nothing to do with the codec being "smart" or not. AC-3 and AAC operate on audio files in different ways so they are not directly compatible/transferrable in the compressed fourier transform domain anyway.
@newpball, if you are looking for another "engineer's lost opportunity", you are again barking up the wrong tree.

What you both DID have right:
DECODING of a lossy compressed signal back to lossless/uncompressed does not incur any additional loss whatsoever, unlesss the decoder is fatally flawed. (rare)
RE-ENCODING back to another lossy signal WILL incur some loss, though the amount and noticeability of that loss is veriable.

So, AC3->WAV: no additional loss (beyond what was already lost with AC3). AC3->AAC: 1 additional generation of loss. AC3->WAV->AAC: 1 additional generation of loss.

Now, if while in the uncompressed WAV domain you choose to do more processing than simple editing, there is also a (very small) generational loss with the WAV file.

Scott

[killerteengohan]

Has nothing to do with the codec being "smart" or not. AC-3 and AAC operate on audio files in different ways so they are not directly compatible/transferrable in the compressed fourier transform domain anyway.
@newpball, if you are looking for another "engineer's lost opportunity", you are again barking up the wrong tree.

What you both DID have right:
DECODING of a lossy compressed signal back to lossless/uncompressed does not incur any additional loss whatsoever, unlesss the decoder is fatally flawed. (rare)
RE-ENCODING back to another lossy signal WILL incur some loss, though the amount and noticeability of that loss is veriable.

So, AC3->WAV: no additional loss (beyond what was already lost with AC3). AC3->AAC: 1 additional generation of loss. AC3->WAV->AAC: 1 additional generation of loss.

Now, if while in the uncompressed WAV domain you choose to do more processing than simple editing, there is also a (very small) generational loss with the WAV file.

Scott

What if you sync a .AC3 track then save it as .AC3 with the same exact bitrate and kHz as the source file? Would the loss be noticeable or would it be the same because its the same specs as the starting file?

[newpball]

Has nothing to do with the codec being "smart" or not. AC-3 and AAC operate on audio files in different ways so they are not directly compatible/transferrable in the compressed fourier transform domain anyway.

Once we can fully agree on something!

AC-3 and AAC are not in the same league!

No surprise of course that AC-3 is preferred by the video standards people for broadcasting, DVDs and Blu-ray.

Dolby...... at least we have to count our blessings as the standards folks did luckily not mandate Bose speakers:

[Cornucopia]

No, you are right that it is no surprise: reasonable & smart teams of people rightly discerned that it makes much more sense to use a codec in existence (AC3) than a codec that hadn't even existed yet (AAC) at the time DVD & ATSC were worked out.

And though AAC existed during Blu-ray's development, the multichannel solutions were NOT available at that time. Plus, at the bitrates commonly used for audio in BD, there is little discernible advantage compared to AC3 (which was already part of the spec for compatibility).

What seems to keep giving you trouble is your misunderstanding of what a "standard" is. They are created so that everybody can "be on the same page" and with reliable compatibility comes acceptance and growth. You and I and ALL of us here at VH have greatly benefitted from those standards. And (usually) they remain set in stone.
But a standard that is NOT backward compatible (i.e. one that throws away older & originally accepted portions of the standard) does a disservice to a vast number of people who originally "bought in" to the standard, and generates bad blood and mistrust.
What you seem to want is for those standards to be re-written (in a non-backward-compatible way), but in real life (due to economics & politics) what happens is that NEW supplemental standards are created, most of which honor legacy material in a backward-compatible way.
You can keep on blowing your blame horn, or you can gain insight & patience and embrace the ADDITION of NEW standards to the family of existing (and probably long-lived) ones. Remember, "they stand on the shoulders of giants".

**********************

Not sure where you were going with that last part - whether it was to denigrate or promote Bose - but it has LONG been my opinion that their products are VASTLY OVERRATED. Most of their hoopla and support is from the sonically unlearned, who are taken in by their reliance on marketing smoke & mirrors (esp. smart brand/technique trademarking) and quasi-psychoacoustic trickery.

**********************

@killerteengohan, think of it this way:
You start with a source uncompressed WAV that = 100% quality.
Compress it to AC3 with a bitrate that gives you ~75% of that quality (at say, 15% of the bitrate).
When you decompress it again (whether permanently to WAV, temporarily to WAV before re-encoding, or temporarily to RAM before the next stage), your uncompressed WAV file is now 100% of the original bitrate, but because of the loss incurred, it is now only 75% of the original quality.
If you Re-compress it again (either from an intermediate WAV or from the temp RAM), usage of the same bitrate as before will give you ~75% of its source, but NOW the source is NOT the original but the decompressed version. So you have 75% of 75%, or 56.25%
(In actuality, because the stuff that was retained in the 1st 75% encode has more regularity & correlation, so using the same bitrate & settings as before might actually get you 85% on the 2nd go-round. But this still is 85% of 75%, or 63.75%.)

Loss is cumulative! You can't have your cake (compression) and eat it too (quality).
"Noticeable" is subjective, only you can decide that.

Scott

[newpball]

... it has LONG been my opinion that their products are VASTLY OVERRATED. Most of their hoopla and support is from the sonically unlearned, who are taken in by their reliance on marketing smoke & mirrors and quasi-psychoacoustic trickery.

I completely agree.

At the same time some (of the same) people die with Dolby. Sure Ray Dolby invented a great way to noise reduce recordings but after that.......?

[Cornucopia]

Dolby Surround was a VAST improvement over the competing forms of matrixed surround from quad days (QS, SQ). This helped pave the way to discreet surround. PL and PL2 were just incremental (but noticeable) improvements on that.
Dolby SR was a major method of noise-reducing major multitrack productions. 24/48/96 track analog recorders (that are still used in pro studios due to their great sound) rely on this.
Dolby C was good technically and a noticeable improvement over Dolby B, but was a "too-little, too-late", for audiocassettes.
Dolby AC-3 was a buy up, but a smart one.
Dolby TrueHD was a buy up (MLP), but a smart one.
Dolby 3D was a buy up (Infitec), and a techically interesting one, but a "too-little, too-late", so wasn't smart.
6+ etc, were incremental improvements on 5.1, but DTS was doing the same thing. Kind of a "armaments race".
Dolby Vision (HDR) and Dolby Atmos (32+ audio channels, incl. independently steerable audio object streams) are their newest babys, and both of those are solid and visionary, as well as being smartly designed to work both with legacy equipment and future enhanced equipment.

That's just some of what was "after that". I wish I was that poor & stupid, laughing all the way to the bank with that kind of track record.

Scott

[hello_hello]

I was going to save the .AC3 as . AAC so saving the .WAV as .AAC should end up the same then if what I said is true. Correct?

Yes, unless the codec is smart (which they seldom are).

I don't get it. In what way would the codec need to be "dumb" for the two methods to be different?

[killerteengohan]

@killerteengohan, think of it this way:
You start with a source uncompressed WAV that = 100% quality.
Compress it to AC3 with a bitrate that gives you ~75% of that quality (at say, 15% of the bitrate).
When you decompress it again (whether permanently to WAV, temporarily to WAV before re-encoding, or temporarily to RAM before the next stage), your uncompressed WAV file is now 100% of the original bitrate, but because of the loss incurred, it is now only 75% of the original quality.
If you Re-compress it again (either from an intermediate WAV or from the temp RAM), usage of the same bitrate as before will give you ~75% of its source, but NOW the source is NOT the original but the decompressed version. So you have 75% of 75%, or 56.25%
(In actuality, because the stuff that was retained in the 1st 75% encode has more regularity & correlation, so using the same bitrate & settings as before might actually get you 85% on the 2nd go-round. But this still is 85% of 75%, or 63.75%.)

Loss is cumulative! You can't have your cake (compression) and eat it too (quality).
"Noticeable" is subjective, only you can decide that.

Scott

I meant, skip the WAV period in my last question. Take the original AC3, sync it by adding cuts where needed, then save as AC3 again with same exact specs. Would it degrade more or stay the same since its still AC3 with the same bitrate and kHz?

If it degraded, what would be getting degraded? Would I really even hear it at all?

[Detmek]

It will degrade. If it will be audible - you need to test for yourself. You may not hear the difference while someone else might. And just because you use same codec and/or same bitrate it dosn't mean the output will be the same.

AFAIK, Apple AAC encoder produces the least degradation after multiple conversions with same quality settings and WMA is the worst. Someone did a test with 100 conversion steps. But I think he didn't test AC3.

[killerteengohan]

Would .WAV or .FLAC be better to work with?

I hear their both lossless but I also hear FLAC is lossless inside a compressed format so I don't know which to go with.

[Detmek]

FLAC should be used as final format if you need lossless. If you want to work on files go with WAV (PCM). You can not work on FLAC files as those have to be decompressed into PCM to work with. As final format, FLAC will be a few times larger then source AC3 files and WAV (PCM) will be 20-40% larger then FLAC.

As a final format in your case, you could go with AC3 or AAC, depending on what is your intent to do with final result. If you are going to author a DVD-Video then AC3. Or, if your hardware player best works with AC3 use it. If you gonna export it as MKV or MP4 you could use AAC.

P.S. You must use AAC if you gonna use MP4 container as AC3 does not work very well inside MP4.

[killerteengohan]

Which would yield the better output with least alteration when its all done?

AC3 - AC3 - WAV - AAC

or

AC3 - FLAC - WAV - AAC

[Cornucopia]

1st has at least 3 generations of loss, 2nd has at least 2, so ALL OTHER THINGS BEING EQUAL the 2nd one would be higher quality.

Scott

[killerteengohan]

I tried AC3 to WAV and AC3 to FLAC.

Why does FLAC wave pattern look slightly different in some places after being zoomed in when compared to the original AC3 while WAV looks exactly the same as the original AC3?

Isnt FLAC also supposed to be lossless as well? What would cause the slight changes?

[newpball]

I tried AC3 to WAV and AC3 to FLAC.

Why does FLAC wave pattern look slightly different in some places after being zoomed in when compared to the original AC3 while WAV looks exactly the same as the original AC3?

Isnt FLAC also supposed to be lossless as well? What would cause the slight changes?

Are you looking at the decompressed FLAC?

Flac is indeed a lossless compression, but obviously the wave will only look the same after it is decompressed.

[Detmek]

I tried AC3 to WAV and AC3 to FLAC.

Why does FLAC wave pattern look slightly different in some places after being zoomed in when compared to the original AC3 while WAV looks exactly the same as the original AC3?

Isnt FLAC also supposed to be lossless as well? What would cause the slight changes?

How did you compress it and where do you look at for difference?

[Cornucopia]

It's a THUMBNAIL overview!!! Of course it's going to very often look different, even with the same source material.
Get over it. If you zoom in to the sample level (for that segment), you will see they are identical.

Scott

[newpball]

WAV (PCM) will be 20-40% larger then FLAC.

Absolutely not, FLAC compresses far better than that!

I am a great fan of FlAC not in the least because it is free!

Obviously the video world has no interest in supporting FLAC they rather support formats that generate royalties for "the syndicate"!

[killerteengohan]

Well if FLAC is compressed, how would you uncompress a FLAC file? I dont think it would be FLAC anymore if its uncompressed.

[Cornucopia]

No. You're right - flac when uncompressed becomes something else(wave, aiff, sd2, raw lpcm, etc).

Scott

[Detmek]

@newpball

Sorry, its 40+% compression, which means WAV will be a bit larger then FLAC.

FLAC is automaticly decompressed during playback. Or, if you import it into audio editing program that supports FLAC format it will internally be decompressed into PCM.

[ndjamena]

The Matrix

FLAC 1,507,853,857
WAV 4,710,433,796

A little less than a third the size, but that's a movie and as always it depends on the source.

[killerteengohan]

how would you uncompress a FLAC file? I didnt even know that could be done.

FLAC is automaticly decompressed during playback. Or, if you import it into audio editing program that supports FLAC format it will internally be decompressed into PCM.

I did import it into an audio editing program (Goldwave and Sony Vegas Pro), but it had the slight wave difference like I mentioned in my post #19.

[killerteengohan]

The original AC3 is on top, the FLAC is on the bottom. if you look closely you can see slight variations in the greens with ease. Some lines are a bit taller after the save to flac and some lines are either gone or smaller in height after the save to FLAC. WAV they were exactly identical with no visible difference that I could find.

https://forum.videohelp.com/images/imgfiles/HxnTDEI.png


It's not exactly a huge amount of changes, I just wondered why is it FLAC looks different and WAV doesn't if their both lossless.

[Detmek]

Floating point to integer conversion. Audacity internally works in 32-bit float and FLAC is always integer. Also, dither may affect this. What settings did you use to create WAV file that looks the same as AC3?