Time Lag between Sub-Cues (solved)

[av8r165]

I'm having a problem with the timing of sub-cues.
I am using 4-5 sub-cues under each cue and they need to stay synchronized.
I'm using Show Cue for band backing tracks, similar to "Forever Everly".

When I initially loaded sub-cues, I found that the first one consistently started about 0.03 seconds ahead of the rest. I worked around it by putting in a “blank” audio file in sub-cue #1. The remaining sub-cues all stayed exactly synchronized.

Now, when I start the cue, each sub-cue lags the previous sub-cue by about 0.01 sec.
The last sub-cue in the list can lag the start by 0.05 seconds or more.
It's not very much time, but it's enough to make the instrument tracks sound audibly out of sync.

Is there something that I'm missing is the setup of the sub-cues?
All of the sub cues were recorded to be exactly the same length.

After my initial workaround, everything worked correctly when I only had about 10 cues loaded in the system. Now that I have about 30 cues in the list, it has become a problem.
I don't know if that's just coincidence or not.

I'm hoping this is a case of "operator error".

I’d appreciate any feedback.

Thanks,
Mike Messick

[Mike Daniell]

Under General Options / Permanent Options / Audio Driver, have you selected 'Do NOT use SCS internal mixer'? You need to do that to get good syncing. Also, the audio file lengths (or the length you play) for each sub-cue of a cue must be the same. For example, if you have one audio file of 5:20.25 and another audio file of 5:21:37 then these may not be synced tightly. You can usually get around this issue by setting an 'end at' point that you can make common to all the files, eg 5:20.24 for the above 2 files. If you take this approach I suggest you apply it to all the files including the shortest, because the actual lengths are held in thousandths of a second, so setting an 'end at' point on all files makes sure they all have the same length in hundredths of a second.

If you still have an issue with this, let me know and I'll give you details of a tracing version you can run which will help me identify what's actually occurring.

[av8r165]

Thanks Mike.

The internal mixer is turned off and I verified the file lengths are the same.

When I first loaded cues into the program, the first sub-cue consistently started 0.03 seconds ahead of the rest.
They maintained that timing throughout the playback (sub-cues 2 thru "X" stayed in perfect sync).
I tried adding a short "empty" audio file as sub-cure #1 and that seemed to fix the issue.

When I delete the "short, empty" cue, I get the same 0.03 sec delay.

Now, what I'm seeing is that each successive sub-cue starts 0.01 sec behind the previous sub-cue and in some cases the difference gets larger as the tracks play.

I had not seen this until I loaded another 10-15 Cues in the program.

Does the program treat MP3 and .wav files any differently? I've converted all of the audio the files to MP3, to save space processing time.

I'll try re-loading all of the Cues and see if that has any impact.

I've been hitting "Pause" and looking at the play time for each sub-cue to determine the differences.

I'm running Show Cue on a Netbook with Windows XP.

[Mike Daniell]

Does the program treat MP3 and .wav files any differently? I've converted all of the audio the files to MP3, to save space processing time.

To save processing time you need to use .wav files, not MP3. The BASS audio library used by SCS internally decodes MP3 to the equivalent of WAV format, so it is more efficient to supply WAV format files.

I've emailed you details for running a trace version.

[Eric Snodgrass]

Wouldn't this sort of problem also be related somehow by the read time of the hard drive? I would think that using many very large files together like that would be affected by the hard drive read time. Might it help using an external SSD for the files, in theory?

[dee99]

Silly though of the day, have you tried altering the amount of pre-loaded files in the options? The default is 5 I think.
Dee

[av8r165]

Looks like problem solved. Mike was a tremendous help tracking down the fix.
I just needed to put a value in the "Link Sync Point" field in the Permanent Options under "Audio Driver".

Mike suggested 50 ms and that seems to have fixed the problem.

Kudos and thanks to Mike for his effort and patience.

Mike Messick

[Mike Daniell]

A couple of other changes we made 'along the way' were to convert all the MP3 files to WAV files and to set the Production Property 'Pre-Load ONLY the Next Manual Cue'. This property prevents SCS trying to open files for the next cue when it starts a cue, which reduces the amount of background processing required when the linked files start playing. This is good if your are using SCS for band backing tracks, but would probably not be advisable if you are using SCS for theatre work. See the Help file for more info.