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Looping sync video with audio

I've been trying to get this to work for far too long now and can not for the life of me get this to work.

I have 3 XD234s on which I would like to have synced videos on a 1 minute seamless loop with one of them outputting audio, prefereably through analogue.

I initially got the videos synced and looping perfectly but once I introduced the audio I kept coming across issues.

With the audio in the video it would play through once then on the 2nd loop onwards would play at double speed while the slaves continued at regular speed. I tried using the same video on all devices but still had the same effect. This was isolated to enabling/disabling audio output causing the double speed.

I tried using brightwall but ended up with a noticeable stutter. this was also true when doing a sync at the media end event to try keep things in line.

I've tried having the audio on a slave in a seperate zone but it quickly loses sync.

This was probably a bit rambley and the wrong topic but if anyone can help please point me in the right direction.

3 comments

  • 1
    Avatar
    Brandon

    The sped-up playback on second pass onward is characteristic of a file that isn't compatible with seamless looping.

    All tracks of the file must match in duration exactly down to the number of samples x sample duration, not just the "duration" metadata.

    See https://support.brightsign.biz/hc/en-us/articles/218066567-Seamless-video-playback for seamless looping guidance across models.

    Even with SOWT (PCM 16-bit little endian) audio, there are certain combinations of audio sampling rate, video framerate, and duration that won't line up.

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  • 0
    Avatar
    Adam Wood

    I have been using AAC as when I've tried Linear PCM audio and I don't get any output at all

    Does any of this stand out as wrong?

     

    General
    Complete name                            : C:\Users\adamwood\Documents\Screen1_20221025.mov
    Format                                   : MPEG-4
    Format profile                           : QuickTime
    Codec ID                                 : qt   0000.02 (qt  )
    File size                                : 309 MiB
    Duration                                 : 1 min 0 s
    Overall bit rate                         : 43.1 Mb/s
    Encoded date                             : UTC 2022-10-25 07:08:04
    Tagged date                              : UTC 2022-10-25 07:08:04
    Writing application                      : Blackmagic Design DaVinci Resolve

    Video
    ID                                       : 1
    Format                                   : AVC
    Format/Info                              : Advanced Video Codec
    Format profile                           : Main@L5
    Format settings                          : 2 Ref Frames
    Format settings, CABAC                   : No
    Format settings, Reference frames        : 2 frames
    Format settings, GOP                     : M=3, N=25
    Codec ID                                 : avc1
    Codec ID/Info                            : Advanced Video Coding
    Duration                                 : 1 min 0 s
    Bit rate                                 : 41.6 Mb/s
    Width                                    : 1 920 pixels
    Height                                   : 1 200 pixels
    Display aspect ratio                     : 16:10
    Frame rate mode                          : Constant
    Frame rate                               : 50.000 FPS
    Color space                              : YUV
    Chroma subsampling                       : 4:2:0
    Bit depth                                : 8 bits
    Scan type                                : Progressive
    Bits/(Pixel*Frame)                       : 0.361
    Stream size                              : 298 MiB (96%)
    Encoded date                             : UTC 2022-10-25 07:08:04
    Tagged date                              : UTC 2022-10-25 07:08:04
    Color primaries                          : BT.709
    Transfer characteristics                 : BT.709
    Matrix coefficients                      : BT.709
    Codec configuration box                  : avcC

    Audio #1
    ID                                       : 2
    Format                                   : PCM
    Format settings                          : Little / Signed
    Codec ID                                 : lpcm
    Duration                                 : 1 min 0 s
    Bit rate mode                            : Constant
    Bit rate                                 : 768 kb/s
    Channel(s)                               : 1 channel
    Channel layout                           : C
    Sampling rate                            : 48.0 kHz
    Bit depth                                : 16 bits
    Stream size                              : 5.49 MiB (2%)
    Default                                  : Yes
    Alternate group                          : 1
    Encoded date                             : UTC 2022-10-25 07:08:04
    Tagged date                              : UTC 2022-10-25 07:08:04

    Audio #2
    ID                                       : 3
    Format                                   : PCM
    Format settings                          : Little / Signed
    Codec ID                                 : lpcm
    Duration                                 : 1 min 0 s
    Bit rate mode                            : Constant
    Bit rate                                 : 768 kb/s
    Channel(s)                               : 1 channel
    Channel layout                           : C
    Sampling rate                            : 48.0 kHz
    Bit depth                                : 16 bits
    Stream size                              : 5.49 MiB (2%)
    Default                                  : Yes
    Alternate group                          : 2
    Encoded date                             : UTC 2022-10-25 07:08:04
    Tagged date                              : UTC 2022-10-25 07:08:04

    Other
    ID                                       : 4
    Type                                     : Time code
    Format                                   : QuickTime TC
    Duration                                 : 1 min 0 s
    Frame rate                               : 50.000 FPS
    Time code of first frame                 : 01:00:00:00
    Time code of last frame                  : 01:00:59:49
    Time code, stripped                      : Yes
    Language                                 : English
    Default                                  : No
    Encoded date                             : UTC 2022-10-25 07:08:04
    Tagged date                              : UTC 2022-10-25 07:08:04

  • 0
    Avatar
    Ken Campbell

    Reviving a dead thread, but having multiple audio streams is probably the culprit in this case.

    Try re-exporting with a single 2-channel / stereo mix, or re-multiplex (using ffmpeg) your existing container file with a single audio stream.

    Ken

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