Export Selection produces tracks out of sync./ wrong length

[TSMusic]

How are you "Exporting"?
I presume that you are using "Export Selected" from the File menu?
If so, how do you ensure that you have selected from precisely 0.000 seconds?

I export the entire track. I select the track by clicking on the track control box (like I have always done). Export Selected. With 1.3.6 I use Other Uncompressed Files with the option for a 32 bit WAV with the default encoding.

If you want I'll zip up the sine wav test project along with my WAV files and make it available for download off of my website. It won't be too large of a file

Tony

[steve]

I think I may know the cause of the problem.

In previous versions of 1.3.x there have been complaints that it was not possible to export an entire track if it had been shifted to the left, such that the track started before "t = 0.0000"

I think there have been a few subtle changes during the beta development of 1.3 in exactly how Audacity handles "Export Selected". The 1.3.6 version appears to have introduced another subtle change, which may be the cause of the problem.

In Audacity 1.3.6

Double click on an audio clip selects the "audio clip". Note the term "audio clip" as opposed to the term "track".
If there are multiple clips in the track, it does not select the track, it selects the audio clip that you double clicked on. Also note that it selects ALL of the audio clip - even if that clip extends to before "t=0.0000".

When you "Export Selected", It does exactly that in a literal sense. It will export ALL the audio that is selected.
It does not export leading or trailing empty space, so if you have an audio clip that starts at t=1.0000 and ends at t=2.0000, then use the selection tool to select from t=0.0000 to t=5.0000, the exported audio will still be 1.0000 seconds long (the leading and trailing empty space is ignored).

There is a distinction here between "empty space" and "silence".
"Empty space" is where there is no wave form shown at all.
"Silence" is where the waveform is a horizontal blue line with zero amplitude.

If you have two audio clips, with a blank (empty) space in between, it would obviously be very inconvenient if that space was ignored, and in fact such space is not ignored. The "Export" (and Export Selected) function will "mix and render" all the selected audio clips to create the exported file and in so doing will create silence in the space between the two audio clips.

The new method does seem to be a bit more complicated than before, but it offers total flexibility when exporting audio clips.

If you have tracks that start before t=0.0000, but you only want to export from t=0.0000, you must only select from t=0.0000
Double clicking on the audio clip will select the entire audio clip.

To select from t=0.0000 to the end of the track, click once on the audio clip that you want to export, then use the "J" key on your keyboard to go to the beginning of the clip. Hold the SHIFT key down (to continue your selection) and press the "K" key to select to the end of the track.

(in most situations you can use "Home" and "End" instead of "J" and "K" - the only difference is that the "End" key will select up to the end of the longest track, not just the end of the current track).

An alternative method is to use the "Selection Toolbar" and enter times directly.

You can also use your previous method of double clicking on the audio clip, but be sure to press Shift+Home to move the start of the selection to t=0.0000

If you have an audio clip that starts after t=0.0000, but you want to export from t=0.0000, the easiest way is to use "Mix and Render" on the track before you Export. (This will also work if the track has been shifted to before t=0.0000 as "Mix and Render" will always produce a track that starts at t=0.0000)

[Gale Andrews]

As this topic had sidestepped away from the original "1.3.5 problems exporting, wav files end up blank" , I split these posts out of it and renamed them as per current title.

That was an excellent analysis, Steve, thanks. Just to add re: "Double clicking on the audio clip will select the entire audio clip", when you have snap-to on this is not true. What double-clicking seems to do then is "something like" select from zero, except that it isn't accurate, for example if you have a 1 second clip 500 ms behind zero, double clicking with snap-to set to hh:mm:ss + milliseconds selects from -50 ms to 950 ms, and export selection gives you a 550 ms track. There tends to be similar behaviour with snap set to seconds, except where the selection is offset behind zero the offset is much larger. I think Jan Kolar mentioned issues like this before. What snap should do (I'd say) is select from the start of the clip, wherever it is behind zero (or after zero), like it would if snap was off (so any truncation of the selection is at the end)? What do you think?


Gale

[steve]

What snap should do (I'd say) is select from the start of the clip, wherever it is behind zero (or after zero), like it would if snap was off (so any truncation of the selection is at the end)? What do you think?

Perhaps it would be more logical;

If "snap to" is selected
and
The track extends to before t=0.0000
and
All of the track is selected by double clicking the track,

then the selection should go either
a) from the snap position before the beginning of the track, to the snap position after the end of the track (in which case the entire track will be selected)
or
b) from the first snap position on the track to the last snap position on the track, so that it gets truncated at both ends by less than 1 snap position unit.

For example; with a track that is 6 seconds long, that has been shifted by 1.5 seconds before t=0.0000 and snapping is set to seconds:
a) would select the full 6 seconds, a
b) would remove the first 0.5 and the last 0.5 seconds to produce a clip that is 5 seconds long.

I personally would go for method a)

[TSMusic]

Sorry for the delay in getting back here. Been a little busy.

I appreciate the detailed explanation but that is not what is happening.

If I make any adjustments to the length of a track it is in the recorded silence at the beginning by deleting a tiny bit to bring the tracks in line. Nothing is being shifted to the left of 0:00

I have always in the past selected the entire track by clicking on the track control box at the left. And that up to 1.3.5 worked fine for all the tracks. (And I have done this more times than I care to think about, I prefer to Audacity for any WAV file editing rather than the track editor in Cubase)

I haven't worked on any new recordings since I last posted this but I will be in the next week or so. I will keep a log of what happens and where.

Thanks

Tony

[Gale Andrews]

What snap should do (I'd say) is select from the start of the clip, wherever it is behind zero (or after zero), like it would if snap was off (so any truncation of the selection is at the end)? What do you think?

Perhaps it would be more logical;
If "snap to" is selected
and
The track extends to before t=0.0000
and
All of the track is selected by double clicking the track,

then the selection should go either
a) from the snap position before the beginning of the track, to the snap position after the end of the track (in which case the entire track will be selected)
or
b) from the first snap position on the track to the last snap position on the track, so that it gets truncated at both ends by less than 1 snap position unit.... I personally would go for method a)

Thinking about it, I'm sure you're right that both ends of the region should lock to the selection unit. What happens now (with audio after zero) is neither your a) nor b) ; the region goes from the snap before the beginning of the clip to the last snap before the end of it. So if I have an 10 second long clip from 2.5 seconds to 12.5 seconds, double clicking with snap on selects 10 seconds starting at 2 seconds and ending at 12 seconds. In this case it selects the same length as if snap was on, though I think I marginally like your idea b) better, as I guess a trim is implied. If I now drag this track .5 seconds behind zero, snap selects from zero to 10 seconds, so now the start is truncated instead of the end, and I don't like that inconsistency very much given we are now exporting audio behind zero. And then we have the further problem that when snapping to milliseconds, the start of the snapped region is not zero but 50 ms behind zero.

However the above is with one track. Once I have three tracks, I sometimes get the exaggerated displacement behind zero mentioned above, even when snapping to seconds. Tony, if your problem is not to do with having audio behind zero or white space in front of it, I think multiple tracks is the problem and that it's possibly tied in somehow with the change in mute/solo behaviour in 1.3.5 (so that the mute/solo buttons became independent again). Exporting multiple tracks mixed to one track is known to create time displacement issues in the tracks that were combined to make the mix, depending on the mute/solo state. You might try with the three tracks exported separately in your experiment, selecting each time the two tracks you don't want to export and Tracks > Remove Tracks before export. You can undo the Remove after the export. Are the offsets correct for each track if there are no other tracks on screen?


Gale

[steve]

If I now drag this track .5 seconds behind zero, snap selects from zero to 10 seconds, so now the start is truncated instead of the end, and I don't like that inconsistency very much given we are now exporting audio behind zero. And then we have the further problem that when snapping to milliseconds, the start of the snapped region is not zero but 50 ms behind zero.

It seems to be worse (more inconsistent) than that. I'm using Audacity 1.3.6 on Linux (Xubuntu 8.04) and selecting a track by double clicking when "Snap" is selected, the selected region is very inconsistent. With "snap" set at seconds, sometimes it will snap to the the second before the end of the track, sometimes after, sometimes to a 0.5 second point, sometimes to the second mark that is more than 1 second away from the end. I think that this must be classed as a bug.

snapping in the wrong place

Screenshot.png (3.54 KiB) Viewed 1346 times

I think I marginally like your idea b) better, as I guess a trim is implied.

I agree that b) is perhaps more logical, but I think that a) would be generally more useful and lead to less user problems.

Tony, if your problem is not to do with having audio behind zero or white space in front of it, I think multiple tracks is the problem and that it's possibly tied in somehow with the change in mute/solo behaviour in 1.3.5

Could it have anything to do with the new "Track Linking" feature? http://audacityteam.org/manual/index.ph ... dio_tracks
It may be worth checking if the problem is affected by switching the Linking button on/off.

[Gale Andrews]

It seems to be worse (more inconsistent) than that. I'm using Audacity 1.3.6 on Linux (Xubuntu 8.04) and selecting a track by double clicking when "Snap" is selected, the selected region is very inconsistent. With "snap" set at seconds, sometimes it will snap to the the second before the end of the track, sometimes after, sometimes to a 0.5 second point, sometimes to the second mark that is more than 1 second away from the end. I think that this must be classed as a bug.

I cannot replicate the problem on Windows with one track open. Are you just alternately clicking and double-clicking and seeing the snap region in different places, or are you dragging the track around with a region visible? I tried that, but it does not create a problem here.

Could it have anything to do with the new "Track Linking" feature? http://audacityteam.org/manual/index.ph ... dio_tracks
It may be worth checking if the problem is affected by switching the Linking button on/off.

I don't believe so, but perhaps Tony can try. I tested with linkage on and off and snap behaviour when the track is behind zero was identical.


Gale

[steve]

Are you just alternately clicking and double-clicking and seeing the snap region in different places, or are you dragging the track around with a region visible?

The image created in my previous post was done as follows:

Audacity 1.3.6 on Xubuntu 8.04
Open Audacity.
"Snap to seconds" selected.
Generate a tone for 10 seconds (sine wave).
Use the time shift tool (F5) and drag the audio to the left to earlier that 10 seconds end time. The selected area does not move.
Click once on the track (clears the selection)
Double click on the track - selects from 0.0 seconds to 10.0 seconds (even if the track is from say -1.3 seconds to +8.7 seconds, or from -5 seconds to +5 seconds).

Clicking on the track information area (below the track name) may select a different region, but again it seems unpredictable.

The selected region will generally behave in a more rational way if the entire audio clip is beyond 0 seconds (as it normally would be) and only becomes weird when the track is pushed to the left before t=0.000

[eeeehaw]

The Red Book CD format spec calls for some quiet lead-in time (1-2 seconds typically) for the first track only. When Exporting to WAV with the time Ruler set to CDDA (75fps), this time may be automatically added to the first track by Audacity. Perhaps Audacity is confusing your split Bass mono track as the "first" CD track, or perhaps you are spliting your bass guitar somewhere into the time ruler, than this may explain the problem, or if CUBASE is assuming this is/will-be CD format in the end. There is a caution note about this extra time in the Audacity online doc where it addresses the Split function (apparently now Split-New).

Anyway, perhaps a clue to help you find a work-around for now. I'd start by checking the time Ruler setting, and if need be dummy up an extra (blank) "first" track, to experiment with. If the indications you find are pointing at the Red Book format theory, then it would be nice for Audacity to add a feature to control the amount of time added to that first Split track (all the way down to zero).