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Audio "Cut in" at Start of Playback

Don Davies

May 05, 2017 19:44

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Experiencing an audio issue with a HD1023.  Outputting analog audio through the 3.5mm jack.

There are two versions of a MP4 video -- Video 1 is selected by GPIO0, Video 2 is selected by GPIO2.  Input is from a Crestron.  The video streams are identical.  As far as audio, Video 1 has narration/music while Video 2 has narration only.  The first part of the audio, which is where the issue appears, is identical between the two videos -- even when zooming into the waveforms in Audacity.

When Video 2 is played, the audio outputs a tiny bit late, cutting out the first 0.2 seconds of narration. Video 1 does does not have this cut.

The cut-in is likely is a result of something in the audio path needing to "wake up."
 We only see this when the video has not played for about 15-20 minutes.  The integrator insists that it isn't the amp or speakers, but I cannot verify without being onsite to plug headphones directly into the HD1023.

Is there anything in the BrightAuthor programming that we should look at?  I realize that we could re-cut the MP4 and add a "blip" of audio at the beginning, hoping it will be enough to get rid of the cut-in, but not enough to hear.  Would rather not do that if possible.

Any suggestions would be appreciated!

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6 comments

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  Bright Scripters May 05, 2017 19:56

  This sound very familiar.

  In our case it was an audio amp, that would go to sleep after few minutes of no audio, so we found a workaround.

  To overcome that, we kept playing a very low frequency noise, at the right level, so it is not noticeable, but enough to keep the audio circuit out of standby mode.

  That noise would only play, while the system is idle, without user interaction.

   

   

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  Don Davies May 05, 2017 23:43

  Thanks for the tip -- I believe the integrator ended up using a setup where an active subwoofer is connected to tiny satellite speakers.  A low signal will probably wake it up.

  Going to setup a transition video before the main content, where I can include the audio.  That way, I won't need to recut the main presentation.

  - Don

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  Don Davies May 10, 2017 22:42

  Solved the issue by outputting low-frequency sound shortly before the audio was supposed to begin.  That seemed to open whatever gate needed to open before audio was played.  My guess is the sub, obviously, to which the satellite speakers are connected.

  The integrator swears that there is no gate on the audio path.  There isn't anything within the Brightsign that may be gating analog audio, is there?

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  Bright Scripters May 10, 2017 23:05

  I can safely say that there is no analog gate in the BrightSign audio chain but hey, there are always surprises...

  Thanks for sharing your solution. Other people's stories keep us sharp :)

   

   

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  Brandon May 11, 2017 00:11

  Nothing comes to mind that could cause that.  Most likely it's some kind of power-saving mode that has to "wake up" - or if it's a wireless device it might have to renegotiate the connection when idle too long.  The latter often happens on Bluetooth-connected speakers.

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  Don Davies May 11, 2017 00:51

  Totally agree.  It would have been nice to have had the client connect headphones, confirm that the cut in does not happen directly out of the audio jack.  But, I am pretty convinced that its something outside the audio path.

  It was really easy to place a tiny video (with some sound) before the main presentation.