Surround (AC3) audio

Note: As of BOS v9.0.101, all Series 5 players support sending compressed audio (AC3 and eAC3 encoded audio) over HDMI and SPDIF.

Series 5 players, other than the AU335, can decode AC3 as a stereo downmix.


AU335 and Series 4 and earlier BrightSign models support passing through AC3 audio over HDMI or SPDIF. However, players do not support decoding AC3 out-of-the-box, so the AC3 data must be passed to an endpoint that can decode it.

To pass through AC3 audio, you must specify the audio settings of the zone outputting the audio:

  1. Select the zone in Edit > Playlist tab.
  2. Click Zone Properties.
  3. Under Audio Output, check the HDMI and/or SPDIF boxes (whichever port(s) are being used to output AC3).
  4. Select Passthrough for the output(s).
  5. Click OK to save the changes.


Note: In BrightAuthor 4.7 and newer, the Presentation Properties, Audio tab settings must be set to Mixed Audio PCM / Compressed or Fixed Audio in order to enable passthrough output.

NoteTo play videos with surround sound, you must encode an AC3 audio layer along with an MPEG2 video layer in a program/transport stream, or MPEG-4 video layer in a MOV.

Note: If using Adobe Premiere to encode the video with the SurCode codec for audio, SurCode needs to be in BlueRay mode, not Dolby Digital mode.



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  • 0


    • Gefen HDMI to HDMI Plus Audio converter, (SKU: GTV-HDMI-2-HDMIAUD, UPC: 845344056111) only supports multichannel analog output for LPCM 5.1 audio input.  It does NOT output analog for compressed audio formats.

      See pages v and 8 in the manual
    • Atlona HD570 will only supports multichannel analog output for LPCM audio input.  It does NOT output analog for compressed audio formats.

      See product page list of supported types through multichannel analog outputs

    When you play the file on your laptop, unless your sound hardware is set to bitstream the audio output, it is decoding the AAC or AC3 and outputting multichannel LPCM.  That's why the Gefen box can decode it to analog.  It also does not work when audio is bitstreamed from a capable computer-based player, as bitstreaming does the same thing the BrightSign player does - it passed the encoded audio directly out to the device, rather than decoding it first.

    When you play it through the BrightSign player, the player doesn't decode the audio, so the encoded AAC or AC3 goes to the Gefen or Atlona device which cannot decode encoded audio.

    The Gefen HDMI to HDMI Plus Audio converter manual ( states this on page v, "This product does not decode audio formats."

    The Atlona HD570 product page ( says "This audio de-embedder supports uncompressed analog LPCM 7.1, 5.1, 2ch through the multi-channel analog outputs. On the optical output it supports Dolby Digital, LPCM 2CH and DTS signals. Dolby TrueHD and DTS-HD Master Audio pass through HDMI connection without being de-embedded."

    Neither box decodes when sent multichannel AAC, Dolby Digital/AC3, DTS, or other encoded audio sources when sent from a hardware Blu-ray/DVD player (that isn't set to downmix to stereo), or a BrightSign player in Pass through mode.

    Depending on your situation, it may work to use multiple BrightSign players using BrightWall or synchronized presentations, each outputting two channels of audio.  Your audio will need to be split into separate stereo files.

    Edited by Brandon
  • 0
    Pascal Gruetter



    I can't  do this: "Audio tab settings must be set to Mixed Audio PCM / Compressed ". The setting is "fixed audio" and I can't change it.

    Thank you for supporting!

  • 0
    Pascal Gruetter

    I tryed again with a HD222 (before: LS422). Here I can check the box. But my decoder mix the 5.1 ac3 to stereo...

  • 0

    Article has been updated.

    The Mixed Audio setting.requires firmware 7.0 or newer.

    Pass through also works in Fixed Audio mode, which is the behavior for firmware older than 7.0.

    Since the player sends the unaltered AC3 data out, if your receiving device is downmixing to stereo, that is a feature or fault of that device.
    Friendly reminder, the community forum is intended for user-to-user discussion. For troubleshooting problems and to ensure a timely answer from a BrightSign representative, please submit a support ticket.

  • 0
    Pascal Gruetter

    Ok. Thank you Brian. I think my MP4 with the AC3 is not fine. Is it possible to import only a AC3 in BrightAuthor wich pass the BrightSign device and will be decodet on my 5.1-Amp?

  • 0
    Pascal Gruetter


    In my old MP4 wasn't a correct ac3  sound file. Now I have a correct MP4, but BrightAuthor doesn't import it... Following message appears:
    This is my MP4, which works fine on a Mac and is decoded correctly (5 separate channels) on my AV-Decoder via HDMI :

    What is wrong with it?

    I have to solve the problem a.s.a.p....

    Thanks to all for support!


  • 0
    Jack Stenner

    Hello. Is there a way to set this in Brightscript if one isn't using BrightAuthor?



  • 0

    Hi Brightsign Team,

    i'm working on an Film Installation which will be shown

    in a Museum. The Film has a Dolby 5.1 Sound Line.

    Can you write down an explanation how to handle Dolby without BrightAuthor
    with different Brightsign Model's as step to step guide?

    So many Artists are using Brightsign Player to display their work but are working

    with MAC's - I think it's time for you guys to aknowledge that and give out some more

    advice for them :-)

    I asked a while ago already to explain how to use FFMPEG and the explanation

    from your side was fantastic - so please!

    I only found this so far:



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