Exported waveform looks different than mixer view (to MP3 and possibly WAV)

[simensen]

I'm new to Audition but I am liking it a lot so far.

I'm trying to get my multitrack file exported to MP3 with all my effects. I have some effects in my effects rack for the master channel.

Trying to export to both WAV and MP3 resulted in unexpected waveform.

Using "File > Export > Multitrack Mixdown" to both WAV and MP3 had same behavior. After export, the file would open and would look as expected. Yet, if I closed the exported file and opened it again from scratch, the waveform looked off.

I was finally able to export a WAV by first "Mixdown Session to New File." The waveform for the WAV looked like what I expected. If I closed the file and opened it again from scratch it still looked correct.

If I "File > Export > File" from this WAV that has the correct waveform and exported to MP3, it looks wrong again.

The "File > Export > Multitrack Mixdown" process appears broken. It looks like it takes the rack effects into account when opening the downmixed file. Yet, this appears to only be visual. The actual file appears to not have these effects applied.

Am I misunderstanding how this should work? Am I doing something wrong?

...

Here is the WAV that I was able to create:

When I try to open an MP3 exported from this WAV, the waveform looks like this:

[ryclark]

Your original mixed down waveform looks very odd in the first place. What does it consist of? It appears to have no dynamic whatsoever in it. It almost looks like a continuous tone.

However that aside what you see in the second waveform of a file opened from an MP3 file is probably what you would expect to see from a highly compressed MP3 file. Not only is MP3 very lossy but the processing needed can, as you have seen, produce bits of audio that didn't seem to exist in the original. What MP3 bit rate did you compress the audio file to?

[simensen]

ryclark​ I'm using one of the stock rack presets for radio announcer. I have two tracks with two separate speakers having a conversation with very little break for 44 minutes. If I zoom into the waveform it looks like this:

You may have answered my question, though. I assumed that the waveform would look the same, or at least close, when exported as MP3.

I guess the frustrating thing is that when exported from the multitrack the waveform looks the same until I open it from scratch. That results in me thinking that maybe the rack effects were not actually applied correctly.

[ryclark]

If you have saved the edited audio as .mp3 Audition will have to decode back into it's native 32bit float .wav format. So then you see all the damage that compressing to .mp3 can do to the audio signal. Although you say 'I'm using one of the stock rack presets for radio announcer' that doesn't really help any of us to know how much audio is lost in the .mp3 format that you are using. Can you quote the bitrate selected such as '128 Kbps'.

[simensen]

ryclark wrote:

Although you say 'I'm using one of the stock rack presets for radio announcer' that doesn't really help any of us to know how much audio is lost in the .mp3 format that you are using. Can you quote the bitrate selected such as '128 Kbps'.

I apologize for the confusion. My statement about the radio announcer preset was to explain why my original waveform looked so odd. Mostly that it's effect seemed to be that it leveled everything out at -3db and when zoomed out it looked like a solid tone as you had pointed out.

I've tried exporting at various bitrates from 64 Kbps to 192 Kbps and I hadn't noticed, visually, much change in the waveform...

It sounds like I am understanding this correctly. Mostly, it appears that I am not doing anything wrong and that I should expect to see a different waveform when encoding to MP3, especially at lower bitrate. This wasn't obvious to me and the fact that the auto-opened version of the MP3 looked different than opening from scratch made me think that something was wrong.

Thanks for your help.