Sync-Locked Tracks

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The Sync-Locked Tracks feature is enabled by the "Sync-Lock Tracks" menu item or button. It ensures that length changes occurring anywhere in a defined group of tracks also take place in all audio or label tracks in that group even if those tracks were not selected. This lets you keep existing audio or labels synchronized with each other even when carrying out actions like inserting, deleting or changing speed or tempo.

Ed 6Jan13: We do not define the term "Sync-Locked Track Group" until over a third of the way down the page:

"The label track defines a Sync-Locked Track Group."
and, IMHO, that's a pretty poor definition. I fleshed it out a little bit further down but I feel that we should define the term here in this "intro".

Gale 12Aug08: ToDo-2 Two Forum users http://forum.audacityteam.org/viewtopic.php?f=46&t=67309#p188517 want Sync-Lock to behave differently and only work on selected tracks so were misunderstanding the text below. Consider tweaking the text.
  • Bill 05Jan13: I made two minor tweaks to the introductory text in an attempt to deal with the confusions identified in the forum thread:
    • "Any selected audio track" -> "Any audio track"
    • "If present a Label Track delimits a track group" -> "If present, a Label Track also delimits a track group"
    • Gale: Thanks, Bill. I see also Peter has put "Sync-Lock selected" in headers. I am not sure how thoroughly we want to use this term. Where we use it, I think it should be "Sync-Lock Selected" to distinguish from standard selection (note that all the tracks in the images are not selected). I've actually undone Peter's change for now as it leads to conflicts with "Sync-Locked" in the text underneath the renamed headers. The Forum topic is not the only place where users have expressed confusion and I'd much rather leave this as an open P2 and deal with it thoroughly after 2.0.3.
Gale 12Nov12: I've always slightly disagreed with the title of this page "Sync-Locked Tracks". The feature I think is called "Sync-Lock Track Groups" and a member of that track is "sync-lock selected". Against that, there seem to be a couple of code functions with "SyncLockedTracks" in their name. The only textual reference I can find in the code to "SyncLockedTracks" is in Track.h "SyncLockedTracksIterator returns only tracks belonging to the sync-locked tracks in which the starting track is a member".

David B. makes the point that now that the Audacity code has screen readers say "Sync Lock Selected" when focus is on a track in a Sync-Locked Group, the Manual is even less clear (it doesn't contain the term "Sync-Lock Selected") .

  • Peter 6Jan13:It does now, I changed h2&3s to contain "Sync Lock Selected" from "Sync-Locked". This will make even better sense once we have re-titled this page to "Sync-Lock Tracks".
  • Peter 4Jan13: I'm minded to agree with Gale that the page is wrongly titled - but the function appears to be calleed "Sync-Lock Tracks" consistently in the GUI: Tracks menu and the roll-over text for the button in the Edit Toolbar. I don't believe that we can change it with a simple displaytitle for this page as there are several linking references thoughout the manual which display "sync-locked tracks. I would suggest we do not tackle this , if at all, until after 2.0.3 release.
  • Gale 06Jan13: Yes it is not really a P1, but is probably a P2 related to the description issues in the P2 above. As I see it, the command in the menu and the button are verbs like all the others, not the name of the feature.
    • Peter 6Jan13: I totally agree with you that for consistency with other pages in the manual that this page should really be titled verbally as "Sync-Lock Tracks". We can either
      1. make a displaytitle for 2.0.3 and do the proper work after
      2. or I am quite prepared to do it now and change all the links to this page. There are 9 English pages that link here, but also several translated pages that link here. So there is a risk in doing this so close to 2.0.3 release - but that risk can be mitigated by leaving behind a re-direct page pro tem.
      • Ed 6Jan13 : change the title and all links
      • Gale 07Jan13: I wasn't suggesting to change the title to "Sync-Lock Tracks" (although that might be slightly better). The point I was making was that the menu item is really a verb or a command that turns on a feature, and that the page title should be the name of or descriptive of that feature. Think that Apply Chains and Edit Chains are described on Batch Processing. The main problems seems to be that
        - people think "Sync-Lock Tracks" turns on a feature that links selected tracks
        - "Sync-Locked Tracks" (the current title) barely exists in the code.

        My money ATM is on retitling as "Sync-Locked Track Groups" but I think the page wants an overhaul for the confusion about what the feature does (the P2 above). A P2 isn't a release blocker so I'm fine with addressing this (and the title) after 2.0.3.

      • Peter 7Jan13: I'm totally happy with that Gale. ToDo-2 for addressing the content and title of this page after 2.0.3

Any audio track in Audacity can be in a group of one or more adjacent tracks that can be Sync-Locked with other tracks in that group. Sync-Lock is off by default, but can be turned on at Tracks > Sync-Lock Tracks or by using the Sync-Lock Tracks button (The Sync Lock Button) in Edit Toolbar.

When Sync-Lock is on an icon (image of sync-lock icon) shows bottom right in the Track Control Panel of each track in a Sync-Locked group provided at least one of those tracks is selected. The icon denotes all tracks that will be affected when a menu operation in a selected track inserts or deletes audio (or otherwise changes the audio's position on the Timeline). The unselected tracks that will be affected are denoted by a patterned "Sync-Lock" selection in the waveform instead of the dark gray of a normally selected track.

Label Tracks can be included in a group so that their labels are synchronised with the audio. If present a Label Track also delimits a track group so that the audio track(s) underneath are in separate group(s). Tracks in those groups will not be affected by actions in the group above unless at least one track in those separate groups is selected. If a group includes more than one label track, the bottom label track delimits the group.

Editing operations on Sync-Locked Tracks

The "Edit" menu commands "Cut", "Delete" and "Paste" will affect Sync-Locked tracks because these commands change the length of the selected tracks(s). All other commands in the "Edit" menu will not affect Sync-Locked tracks because these commands do not change the length of the selected track(s). These commands are: "Split Cut", "Copy", "Trim Audio", "Split Delete", "Silence Audio", "Split", "Split New", "Detach at Silences", and "Duplicate".

Examples of Editing Operations on Sync-Locked Track Groups:

Ed 6Jan13: visually it looks strange to have the section title in the same font size but not bolded as the above "Examples of…" which, because it is bolded, looks bigger.

Ed 6Jan13: it looks to me like none of the following images have "hover text" currently; I'm going to add hover text but would like someone more knowledgeable to verify that I "got it right".
Ed 6Jan13: another question for Connie…
Edit > Remove Audio or Labels > Cut:
or
Edit > Remove Audio or Labels > Cut:
I know this is subtle! I feel that the colon should not be in the background colored style. Everywhere else in the manual I have tried to ensure that it was not– so I'm going to do so again here.
Ed 6Jan13: In this section we have a bulleted list, the list is preceded by a line of text in triple-equal-sign big bold text (I added a colon to it so that the bullet points had an anchor). With the images and the text for each bullet point the fact that it is a bulleted list gets lost. Additionally, the initial text after the bullet does not give enough information; the first few are just menu spans with no descriptive text and the last few are so terse as to be meaningless. I propose that, since these bulleted items are so long, the text following each bullet point should be a full sentence (not necessarily long) describing the operation which will ensue.

  • Gale: Please give an example in this ednote of the text you would have for Edit > Remove Audio or Labels > Cut.
  • Edit > Remove Audio or Labels > Cut:
Before Edit > Remove Audio or Labels > Cut
Two sync-locked tracks with audio selected in the top track, ready to be cut.
After Edit > Remove Audio or Labels > Cut
The two sync-locked tracks from the previous image, after the cut operation, showing that audio was removed from both tracks, keeping them synchronized.
Result: Audio has been cut from the lower track as well as the upper track. The same thing happens for Edit > Remove Audio or Labels > Delete because those commands remove audio from a track and the following audio on all sync-locked tracks must move to remain synchronized.
Before Edit > Remove Audio or Labels > Silence Audio
Two sync-locked tracks with audio selected in the top track, ready to be silenced.
After Edit > Remove Audio or Labels > Silence Audio
The two sync-locked tracks from the previous image, after the silence operation, showing that audio was silenced in the upper track but nothing happened to the lower track.
Result: There has been no change in the lower track - this is because "Silence Audio" does not move (change the time position of) any audio in the selected track.
Before Edit > Remove Audio or Labels > Trim Audio
Two sync-locked tracks with audio selected in the top track, ready to be trimmed.
After Edit > Remove Audio or Labels > Trim Audio
The two sync-locked tracks from the previous image, after the trim operation, showing that the leading and trailing audio was trimmed in the upper track but no change was needed to the lower track to keep it synchronized.
Result: There is no change in the lower track - although the length of the upper track has changed, it remains synchronized with the lower track.
Here is the same project but now there is no selection. The cursor is in the top track, and that track is selected as can be seen by darker gray color of the Track Control Panel.
You need to look for the sync-lock icons in the Track Control Panels to know that these tracks are sync-locked.
Before Edit > Paste
Two sync-locked tracks with no audio selected; the cursor is in the top track which is selected and ready to have audio pasted in.
After Edit > Paste
Audio has been pasted into the top track moving the following audio to the right; silence has been inserted in the lower track corresponding to the length and position of the pasted region.
Result: Audio is pasted into the top track moving the following audio to the right; silence is inserted in the lower track to keep it synchronized with the top track.
  • Label track defined Sync-Locked Track Groups
Here is a project with two mono audio tracks above a label track all of which are above a stereo music track. There is a selection in the upper mono audio track. The sync-locked selection extends into the second mono audio track and into the label track but not into the stereo music track. The label track defines a Sync-Locked Track Group comprised of itself and the two mono audio tracks above it; this can be verified by examining the Track Control Panels and observing the sync-lock icons at the lower right-hand corners.
Before Edit > Remove Audio or Labels > Cut
Two mono tracks (one containing a selection to be cut) above a label track that separates a stereo track below into a second Sync-Locked Track Group.
After Edit > Remove Audio or Labels > Cut
The tracks above the label track remain synchronized after the cut, while the stereo track in the second Sync-Locked Track Group is not affected.
Result: Audio is removed from the two mono audio tracks and labels in the label track are moved so that the three tracks remain synchronized. No audio is removed from the stereo music track.
A Sync-Locked Group may have multiple label tracks as long as the label tracks are together at the bottom of the group.
  • Selecting in label tracks
Selections can be made in a label track and the Sync-Locked selection will extend into any audio and label tracks in the group.
Before Edit > Remove Audio or Labels > Cut
SyncLock17.png
After Edit > Remove Audio or Labels > Cut
SyncLock18.png
Result: The selected portion of the label track is removed, including the label spanned by the selection. Audio is removed from the Sync-Locked audio track as well.

Time stretching operations on Sync-Locked Tracks

The following effects, when applied to a region in a selected track in a Sync-Locked group, will cause the length of non-selected tracks in the group to be adjusted to match the change in length of the selected track. Audio before and after the selection will remain synchronized. Audio within the selection may or may not remain synchronized, as the time stretching effect is not applied to the Sync-Locked tracks.

  • Change speed: Sync-Locked tracks will be adjusted by having the selected region(s) shortened (if the change in speed is positive), or have silence inserted after the selected region (if the change in speed is negative).
  • Change Tempo: Sync-Locked tracks will be adjusted by having the selected region(s) shortened (if the change in tempo is positive - faster), or have silence inserted after the selected region (if the change in tempo is negative - slower).
  • Repeat: If applied to a selection that does not end on the end of a track, silence is inserted in the Sync-Locked tracks where the repeats are placed in the selected track(s)
  • Sliding Time Scale/Pitch Shift: If the time-scale changes shorten the selection then the Sync-Locked tracks will be shortened to maintain time synchronization among the tracks; if the time-scale changes lengthen the selection then the Sync-Locked tracks will have silence inserted to maintain time synchronization among the tracks.
  • Truncate Silence: Removes audio from Sync-Locked tracks to maintain time synchonization with remaining sections of the selected track.
  • Delay: If applied to a selection that does not end on the end of a track, silence is inserted in the Sync-Locked tracks where the delays are placed in the selected track(s) to maintain time synchronization among the tracks.

All other effects do not change the length of the selection, so will not cause any changes to the Sync-Locked tracks.

Examples of time stretching operations on Sync-Locked Tracks

Before Effect > Change Speed
SyncLock09.png
After Effect > Change Speed
with a setting of 25%, which makes the selection faster and shorter
SyncLock10.png
Result: Audio has been removed from the lower audio track. Note that in this case audio within the selection does not remain in synchronization since the Change Speed effect is not applied to the Sync-Locked track. Audio before and after the selection remains synchronized.
Before Effect > Repeat
SyncLock11.png
After Effect > Repeat
with 3 repeats
SyncLock12.png
Result: Silence has been inserted into the lower audio track.

Time shifting operations on Sync-Locked Tracks

  • Tracks > Align Tracks: All of the "Align Tracks" commands (with the exception of the "Align Tracks Together" command) will move all tracks in a group by the same amount, even if this means pushing the start(s) of some track(s) before zero on the timeline.
By its nature the Align Tracks Together command cannot respect sync-lock since its job is to align the selected tracks so they all start at the same point on the timeline.
  • The Time Shift Tool: Using the Time Shift tool on any audio track in a Sync-Locked Track Group will cause all clips in all audio tracks, and the label track, to move. This is true even if none of the tracks are selected.

Examples of time shifting operations on Sync-Locked Track Groups

Before Tracks > Align Tracks > Align with Cursor
SyncLock13.png
After Tracks > Align Tracks > Align with Cursor
SyncLock14.png
Result: The selected track is moved so the start of the track aligns with the cursor. The Sync-Locked track moves by the same amount.
  • The Time Shift Tool
Before time shifting the tracks
SyncLock15.png
After time shifting the tracks
SyncLock16.png
Result: All the tracks move together.
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