KVR Audio

synaptic flow · Post by **synaptic flow** » Thu Oct 12, 2017 4:08 am

So I have used Sound Forge for at least a decade now. I have SF Audio Studio 10 and SF Pro 10.

And recently I discovered something very troubling and I'm pretty unhappy about it because I think I'm going to have a lot of further disappointment ahead of me.

Recently I started using a spectrum analyzer to look at the mp3s that I DJ with. I will often use SF and FL Studio to make my own remixes or edits of songs. Sometimes the source is WAV and sometimes it is mp3. Sometimes I will just give older songs a volume boost with the SF limiter.

I began to notice that when I looked at mp3s that were created by Sound Forge, the spectrum analyzer would show that my mp3s were identified as 320kbps yet the frequency graph shows that they are a much lower bit rate! This is beyond bad because it is possible that I have messed up tons of mp3s and songs that I edited and resaved.

So just to make sure you guys understand what I'm saying. When I re save an mp3 in either version of Sound Forge, my spectrum analyzer says that it is in fact 320kbps but the frequency information reads more like it is 192kbps. A lot of information is missing.

So I began to download various freeware editors and even a video editor. Every single one correctly re saves or converts to mp3 and the spectrum analyzer shows a much greater amount of frequency range in the mp3.

Here is the real kicker. In most cases, the file sizes are the same no matter what editor I use.

How on earth is Sound Forge saving my mp3s at the wrong bitrate, yet having the same file size? And if it's the same filesize, how is more frequency information missing that what should be?

I really like Sound Forge and hate to have to start using two editors or going with something else totally.

I'm sick at the thought of how many of my songs might be ruined and a lot of them I won't have unaltered backups for.

planetearth · Post by **planetearth** » Thu Oct 12, 2017 5:27 am

Do you have SF set for "constant bit rate" or "variable bit rate" when saving your MP3s? If it's set to "variable", or if you allow it to change anything while it's creating the MP3, you may end up with a lower average bitrate.

And unless something is changing the sampling frequency of the MP3 (which, again, would be done when saving the file), you really shouldn't see much difference in the frequency response.

Steve

synaptic flow · Post by **synaptic flow** » Thu Oct 12, 2017 5:36 am

Hello Steve. Thanks for writing.

I always set it to a constant 320kbps. I forgot to mention this this also happens when I convert a WAV file to mp3.

I am used to seeing my 320kbps mp3s show a frequency range reaching 20khz, but now Sound Forge is making converted WAV files and mp3s at 320kbps only reach 15khz. That suggest that it is not a true 320kbps file. I cannot understand why this is happening.

AnX · Post by **AnX** » Thu Oct 12, 2017 5:45 am

I always save as wav and use a diff app to convert and tag mp3s. Have done for 15 years... i dont think ive ever saved a file as mp3 in SF.

If you are saving as mp3 to save space, 320 is high, why not use ogg or flac?

planetearth · Post by **planetearth** » Thu Oct 12, 2017 5:45 am

synaptic flow wrote:Hello Steve. Thanks for writing.

I always set it to a constant 320kbps. I forgot to mention this this also happens when I convert a WAV file to mp3.

I am used to seeing my 320kbps mp3s show a frequency range reaching 20khz, but now Sound Forge is making converted WAV files and mp3s at 320kbps only reach 15khz. That suggest that it is not a true 320kbps file. I cannot understand why this is happening.

Try creating a new template for your MP3 converter within SF. Make sure all the settings are exactly the way they should be: Constant bitrate, and 44.1 kHz sample rate. It could be that the template you're using is corrupt--though that's unlikely.

Steve

synaptic flow · Post by **synaptic flow** » Thu Oct 12, 2017 5:50 am

I made a new template and the problem remains. I may end up having to use two programs after all.

planetearth · Post by **planetearth** » Thu Oct 12, 2017 6:00 am

synaptic flow wrote:I made a new template and the problem remains. I may end up having to use two programs after all.

Out of curiosity, does it happen with any other MP3 template in SF (such as one of the other factory ones), and does the analyzer you're using now show that any of your older MP3s suffer from this, or is this a new thing (again, according to the analyzer you're using now)?

I have SF 10, and if you'd like to send me a .FLAC or .WAV of what you're trying to convert, I'll try it right now, to see if mine does the same. I haven't known mine to show a bitrate other than what I chose in the template, unless I changed the "quality" or "constant/variable" setting.

Steve

yellowmix · Post by **yellowmix** » Thu Oct 12, 2017 6:09 am

I generated 1 second of white noise in Sound Forge Pro 11.

I saved it as WAV, 44.1kHz, 16-bit. I saved it as mp3 using the "320 Kbps CD Transparent Audio" factory template.

I analyzed both in spectrum analyzers. There is no frequency cutoff at 15 Khz: https://imgur.com/a/QtVRL

What spectrum analyzer are you using? What kind of algorithm does it use and how big is the FFT window? Make sure you give it a sufficient window. I used 8192 with Blackman-Harris.

yellowmix · Post by **yellowmix** » Thu Oct 12, 2017 6:11 am

Please post a screenshot of the MP3 save settings.

synaptic flow · Post by **synaptic flow** » Thu Oct 12, 2017 4:24 pm

To yellowmix:

I hadn't considered that my spectrum analyzer might be goofing up, but it does only show this error in conversions done on Sound Forge. It shows the full 20khz when I convert in any other program.

I use SPEK http://spek.cc/ to analyze frequencies. It really has no settings to adjust.

I will show a file. I made a "clean edit" of a song. It was purchased as an mp3 and converted to WAV to do my edits. You will see that the WAV reaches 20khz. It would have shown a higher range if it had been initially purchased as a WAV of course.

Then you will see what it shows after I convert it to mp3 in Sound Forge. A lot of frequency is gone, but you see that Speck says it is indeed 320kbps.

synaptic flow · Post by **synaptic flow** » Thu Oct 12, 2017 6:39 pm

Thanks for trying to help everyone. I'm headed to work for the next 11 hours, so I will be unable to read or respond to this anymore until late tonight.

yellowmix · Post by **yellowmix** » Thu Oct 12, 2017 11:36 pm

I downloaded Spek (for Windows), generated 1 second of stereo white noise in Sound Forge, saved it as WAV and as MP3 (highest quality). There is no frequency cutoff or noticeable degradation in Spek:

Noise.wav.png

Noise - Highest Quality.mp3.png

You explained your workflow so I did something similar. I saved the mp3 as wav, then re-encoded it back to mp3.

Noise - Highest Quality (from WAV from mp3).png

You can see some degradation near Nyquist but well above 16 kHz.

So I'm stumped. Can't replicate what you're experiencing and I think it has something to do with the specific mp3s you have.

As for Spek seeing the cutoff file as 320kbps, it's in the mp3 header so we know at least that's correct. So the question is, is it in the encoding or is there some weirdness happening when that mp3 is converted to a second generation?

Can you try to replicate my experiment? That is, with self-generated white noise? If there is no cutoff then we have narrowed it down to the specific file.

synaptic flow · Post by **synaptic flow** » Fri Oct 13, 2017 6:23 pm

I'll have to try to recreate it tomorrow. I uninstalled Sound Forge Pro so I could try Audio Studio again. Audio Studio won't let me generate white noise.

I don't have time right now due to work.

I didn't want to do this, but I think I will also try installing Sound Forge to one or two of my laptops (which are only for DJ'ing) and see if the problem happens there to.

CTStump · Post by **CTStump** » Sat Oct 14, 2017 1:41 pm

Some converters have a high and low pass filter built in to the conversion process. Could be the case in your situation and if so there may be a setting in the preference dialog.

When ever I convert I always rolloff the highs to 16 k to reduce any artifacts in the conversion process and shelve the low to about 20 k with a bandwidth of 4 to take some of the inaudible strength out of the process prior to the conversion. This works quite good most of the time.

The file size is the same whether I do this or not which seems to indicate what is happening to you. Check those encoder settings a see if someting is set to prefilter the file prior to the process or set in the preference.

320k is really high and should be as good as uncompressed wave. Should be in no way noticeable even to the most discriminate ear.

synaptic flow · Post by **synaptic flow** » Sun Oct 15, 2017 3:28 am

Updates:

Installed Sound Forge to another computer and the problem remained exactly the same.

Recreated wave files like recommended and the problem remains.

I do not see any advance settings to tinker with for the mp3, other than speed or quality and the misc stereo settings.

I'm starting to reach for crazy ideas now. Could a virus do this? I haven't detected one during any scans.

Yes I'm one of those who uses his internet computer to edit and make music on. And I use my laptop's for DJ'ing.

It's just so crazy because I didn't always have this problem. Also I know it shouldn't be the fact that I am running Win 7 Pro 64bit with 32bit versions of Sound Forge. (I didn't always run a 64bit OS)

I am truly beyond perplexed.

It looks like my only option is to use a separate program for the mp3 conversion. This kind of sours me on Sound Forge for good. And here I was looking towards the Audio Studio 12 upgrade.

Sound Forge users? A troubling problem...