Selecting & Deleting very small pieces of audio

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DJO
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Selecting & Deleting very small pieces of audio

Post by DJO » Mon Feb 20, 2012 3:26 pm

I have a couple of live (concert) mp3 music files. In the form I recieved them there's not a smooth transition from the end of one file to the beginning of the next. Upon zooming in on the end of one file or the beginning of another I notice a tiny bit of silence (flat blue line) causing this brief but irritating interuption in the listening experience. I was under the impression I could simply select that small area (typically using zoom in first to make sure I can see/capture/select all the avail. silence), hit delete in the edit menu then save the file ("save as" in order to protect the orig in case I need to go back). I swear I've done this in the past with success every single time (many, many times!), but for some reason when doing this recently I noticed that it does not delete all of the area I've selected. After saving, closing and going to listen to what I thought would be an edited track I notice pretty much the same issue still present. I go back reopen the newly saved file and the time length is almost the same as it orig. was. It seems to take a little off, but not the amount I selected. Example if the original track is 6m32.43 and I delete say 0m00.30, after I save and reopen the file it may say 6m32.28. I can't figure out exactly how it's calculating what to take off or why if I'm selecting 0m00.30 it's not deleting the whole amount. I know we're talking about really, really small time frames but I swear this used to work - no matter how small! I did look into the "Snap To" issue which I thought could be the problem, however my Snap To Box is NOT checked. I then thought (guessing) it had something to do with the fact the files in question are 48hz as opposed to the typical 44hz, however I went back and tested a variety of different, unrelated files and those too are experiencing the same issue.

I have not made any changes to my software (1.3.13(?) or 4(?) beta) and this is the same version that I swear I have been able to do successful edits of this type in the past. Am I going crazy or missing some step?!

This is really irritating me (I know it's partly OCD!!) Any help would be greatly appreciated.

billw58
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Re: Selecting & Deleting very small pieces of audio

Post by billw58 » Mon Feb 20, 2012 3:54 pm

Make sure that "Snap To" is not checked in the Selection Toolbar.

http://manual.audacityteam.org/man/Selection_Toolbar

-- Bill

DJO
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Re: Selecting & Deleting very small pieces of audio

Post by DJO » Mon Feb 20, 2012 4:30 pm

Hi Bill - I did doublecheck that and unfortunately it is NOT checked:( Wish it was that easy. This is really driving me crazy.

DJO
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Re: Selecting & Deleting very small pieces of audio

Post by DJO » Mon Feb 20, 2012 4:47 pm

Hi Bill - I wish that was the issue. I have doublechecked that and the box is NOT checked, which I understand it shouldnt be for what I'm looking to accomplish.

Any other ideas?

PGA
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Re: Selecting & Deleting very small pieces of audio

Post by PGA » Mon Feb 20, 2012 6:48 pm

Could it have anything to do with Preferences...Tracks..."Enable dragging of left and right selection edges"?

DJO
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Re: Selecting & Deleting very small pieces of audio

Post by DJO » Mon Feb 20, 2012 7:01 pm

Good point PGA, but I've already looked into that also. Mine is checkmarked which is the default and I haven't changed it.

steve
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Re: Selecting & Deleting very small pieces of audio

Post by steve » Mon Feb 20, 2012 7:53 pm

DJO wrote:I have a couple of live (concert) mp3 music files. In the form I recieved them there's not a smooth transition from the end of one file to the beginning of the next. Upon zooming in on the end of one file or the beginning of another I notice a tiny bit of silence (flat blue line) causing this brief but irritating interuption in the listening experience.
That is a limitation of the MP3 format.
The MP3 format encodes the audio data in "frames" (small blocks of data). The exact start position of the audio in the first frame is undefined, so there is always a short amount of lead-in silence at the beginning of an MP3. There's nothing that you can do about that other than use a different audio format. Yes you can use Audacity (or another audio program) to trim off the silence, but as soon as you encode the exported audio in MP3 format, a small amount of silence will reappear at the beginning of the track.

Lossless formats such as WAV FLAC and AIFF don't have this problem.

Of the "lossy compression formats:
OGG does not have the problem.
MP3 and WMA do have this problem.
AC3 has the problem, though usually the added silence is much smaller than in the case of WMA and MP3
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)

PGA
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Re: Selecting & Deleting very small pieces of audio

Post by PGA » Mon Feb 20, 2012 8:47 pm

If you have the two sound files in Audacity as two separate tracks, you can always use the Timeshift tool to slide them so that the silences overlap - and thus no longer exist - in your final mix-down to whatever file format you decide to use for the export.

DJO
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Re: Selecting & Deleting very small pieces of audio

Post by DJO » Mon Feb 20, 2012 9:02 pm

PGA wrote:If you have the two sound files in Audacity as two separate tracks, you can always use the Timeshift tool to slide them so that the silences overlap - and thus no longer exist - in your final mix-down to whatever file format you decide to use for the export.
Yeah, I've done that with success. Call it OCD or what (you know how audiophiles can be with details!) but the thing I didn't like about that is when you have many tracks making up an album and stringing them all together and then if you'd want to listen to one say in the middle that's now linked maybe with one before or after you have to scan the audio to find the beginning of the song. Upon using this method and exporting they save as one file blended together. Unless I'm missing a step and maybe after I save I can go back and split at a chosen point between songs without introducing any silence????? I would be interested to hear if that's an option. Seems like a lot of work - time shift them together, save as one and then resplit.

Moreover (and this goes out also to the senior forum member who previously answered my post) I swear I've done the same exact thing I'm trying to accomplish at least a couple of dozen times in the past and it worked... with the BETA version. I just can't figure out what changed and it's driving me crazy!!!!!!!!!!!!!!!

billw58
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Re: Selecting & Deleting very small pieces of audio

Post by billw58 » Mon Feb 20, 2012 9:38 pm

Try this exact sequence of steps.
New Audacity project
Import two MP3 files that should flow together
Delete the gap
Save the project
Exit Audacity
Start Audacity and open the project.

Is the gap back, or is it still gone?

-- Bill

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