First 5 seconds of Export buzzing

[Gale Andrews]

I, too, am having the same problem with Audacity on my 13" mid 2013 MacBook Air.

Which version of Audacity exactly? Please see the pink panel at the top of this page.

As an example, the audio from our radio show today--went out live on-air clean. Was clean on the MP3 recording device. When I dumped it into Audacity and exported as MP3, WAV, anything else, for online posting, crackle became audible in first part (and seemingly randomly throughout). But it's not because the audio is maxing out, it seems to be something else.

Was this on one track in Audacity, or were there multiple tracks?

If there are multiple tracks that don't all have audio starting at time zero, you could try generating a little silence at the start of each track.

Do you have high-quality dither set to "Shaped"?


If not, try that .


Gale

[kozikowski]

You're talking about that light ticking in the background, right? Mavericks? Did you upgrade to 10.9.2?
Koz

[Gale Andrews]

There is also some kind of squeaky distortion near the start, which I assume is compression damage.

However some people who had audio tracks not starting at zero found that the Audacity exports added distortions.

Either way, you and I can hear the ticks in the SoundCloud example. So the damage is in the exported file and it's not a playback problem as I understand it.


Gale

[Jbologna]

Thanks, Gale and Koz,

Sorry about that -- I'm using Audacity version 2.0.5. My OS x is version is 10.9.2.

Yeah, the crackle sound seems to be introduced only after exporting from Audacity, not on the original file.

There were two tracks, the second of which didn't start at zero, as you mentioned. I just generated silence all the way back to zero on that track. On export, it seems to have worked! No more crackle on the final MP3.

I'll be working on more sound in the next few weeks, so I'll try that trick and see if it continues to work.

Many thanks,

Jamie

[kgagne]

I too have had this problem with Audacity 2.0.5 and Mac OS X 10.9.2 and with a high-quality dither of "Shaped".

It seems to happen only in multi-track sessions where one track starts later than the other. Adding silence to those later tracks so that they all start at the same time fixes it.

I have an AUP project and exported MP3 this problem, if anyone would like to hear or play with it.

-Ken

[Gale Andrews]

I have an AUP project and exported MP3 this problem, if anyone would like to hear or play with it.

By all means if can you post a link to the project, Ken, we'll look at it. Set it up so that with Real-time dither set to "None" and High-Quality dither set to "Shaped", you can hear the problem in the project then export WAV and hear the problem in the exported WAV.

Do you have MacBook Pro?

If you can reproduce the problem in 2.0.5, what happens if you open that project in 1.3.13 ( http://audacity.googlecode.com/files/au ... 1.3.13.zip ) ? That was the last version that rendered white space between time zero and first audio.


Gale

[kgagne]

Gale,

Thanks for the quick reply! I do indeed have a MacBook Pro, purchased November 2013.

Here is the Audacity file w/exported WAV, both exhibiting this behavior:

https://drive.google.com/file/d/0B15Dl3 ... sp=sharing

This project file sounds fine in Audacity 1.3.13, which also exports a flawless WAV.

-Ken

[Gale Andrews]

I do indeed have a MacBook Pro, purchased November 2013.

Here is the Audacity file w/exported WAV, both exhibiting this behavior:

https://drive.google.com/file/d/0B15Dl3 ... sp=sharing

This project file sounds fine in Audacity 1.3.13, which also exports a flawless WAV.

Thanks, Ken. I can reproduce a playback problem in the project and in your exported file on my Mac Mini from 2013 on OS X 10.9.2. Audacity 2.0.2 ( http://audacity.googlecode.com/files/au ... -2.0.2.zip ) does not have the problem but 2.0.3 ( http://audacity.googlecode.com/files/au ... -2.0.3.zip ) and later do show the problem.

But in 2.0.3 or later I have not managed to export a 16-bit WAV that renders the playback problem, either with "High-quality Conversion" dither off or on.

It seems both project tracks are in your exported file. Are you using File > Export or File > Export Selection? Can you please post an image of your Quality Preferences (Audacity > Preferences then choose "Quality" on the left)?

Other things I found:

• If in the upper track I delete the audio that does not start at zero (leaving an empty track), the playback problem goes away.
• If I undo the delete then mute the upper track, the playback problem goes away.
• If I unmute the upper track then move it below the audio track that starts at zero, the playback problem goes away.
• If I generate silence from time zero to 1 second in the upper track then play both tracks, the playback noise starts after 1 second.
• Audio to buffer settings make no difference.

@Ken, in 2.0.5 can you export 16-bit WAV (without changing Quality Preferences) with the upper track moved down? To do that, drag the track down with the mouse where you see "32-bit float" in the track. Does that WAV have the noise?

Do you agree that 2.0.2 does not show the playback or export problem?

@others, can you please try the project in 2.0.6-alpha on other versions of OS X? I tried on Windows 7, there is no playback problem.



Gale

[kgagne]

Gale,

My latest tests with the file I provided, in both Audacity 2.0.2 and 2.0.5, is that the static can be heard the first time I play back the file, but not on subsequent playbacks (unless I close and reopen the file).

I can export a WAV with the static in 2.0.5 but not 2.0.2. After swapping track positions, I cannot export a staticky WAV in 2.0.5. Swapping track positions eliminates the static entirely in 2.0.2 but not 2.0.5. Even with tracks swapped, 2.0.5 can still export a staticky WAV. I am using "Export", not "Export Selection".

Here are my audio quality settings.

The file I provided is an excerpt from a much larger recording that's several gigs in size and has more tracks. That file seems to exhibit the static more consistently.

-Ken

[Gale Andrews]

My latest tests with the file I provided, in both Audacity 2.0.2 and 2.0.5, is that the static can be heard the first time I play back the file, but not on subsequent playbacks (unless I close and reopen the file).

Thanks for testing. On my Mac mini, in 2.0.5 or 2.0.6-alpha, the playback is noticeably less crackly first time, then subsequent times is extremely crackly in the first 5 seconds or so, then intermittently crackly thereafter. I presume the relevance of 5 seconds or so is that this is the first audio block file at 32-bit float.

What happens if you restart 2.0.5, open the project then export, without playing the project? Is the WAV still ticky?

I can export a WAV with the static in 2.0.5 but not 2.0.2. After swapping track positions, I cannot export a staticky WAV in 2.0.5. Swapping track positions eliminates the static entirely in 2.0.2 but not 2.0.5. Even with tracks swapped, 2.0.5 can still export a staticky WAV. I am using "Export", not "Export Selection".

I'm not quite clear from the above whether you can ever export a ticky WAV from 2.0.5 after swapping track positions. Does it vary - some exports with swapped tracks are crackly and some not?

If you don't swap the tracks in 2.0.2, is the export still ticky, whether or not you play the project?

You have dither enabled for export in http://tinypic.com/r/2w4a4ia/8 , as is default. Can you try setting the second "Dither" setting (under High-quality Conversion) to "None" and then export from 2.0.5 without tracks swapped. That does not stop the crackle for me.


Gale