Latest post Wed, Jun 12 2019 11:14 AM by Rich Laws. 1 replies.
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  • Tue, Jun 11 2019 4:25 PM

    Media Composer 18.9 audio only clips causing problems with AMT2 (PCM is sometimes one sample less than clip duration requires)

    Hi all,

    Just a note as I have been working with a customer in Argentina with a partial offline issue.  In this workflow, the customer is using our product to add proxy audio to existing audio only clips created by Media Composer 18.9.   The PAM status shows that the proxy audio is "partial offline" randomly for some clips.   What I have found is in the case where this occurs, the PCM sample count is always 1 audio sample less than the track duration.  Confirmed with AAF and MXF dump of the PCM MXF files.  material package is 30fps NDF.  Currently our software doesn't account for "padding" extra samples to feed AMT2 when building a proxy to account for source content being less than material metadata reflects.  Not sure if this is to be consider an issue with Media Composer audio only generation.  (math error somewhere?)  when it occurs, it's always 1 sample shy of what it needs to be to reflects the clip length in the material package.

    Evaluating what's involved with trying to work around this on our end but thought I'd point it out.  I can provide the MXF files and AAF files for the client clips if needed.

    (See bolded text below)

     [ SourceMob ]

     MobID: 060a2b340101010101010f00-13-000000-{ 5cbdd9e7-c8d8-0036-060e-2b347f7f2a80 }

     Name: "CS 190418 SPORTHUANCAYO VS MONTWANDERERS HL,Audio Mixdown,3"

     Slots: Strong Object Reference Array [1] of MobSlot

      kAAFTypeID_MobSlotStrongReferenceVector [0]: 

        [ TimelineMobSlot ]

        SlotID: 1

        SlotName: ""

        Segment: 

          [ Sequence ]

          DataDefinition: Sound

          Length: 41865824

          Components: Strong Object Reference Array [1] of Component

           kAAFTypeID_ComponentStrongReferenceVector [0]: 

             [ SourceClip ]

             DataDefinition: Sound

             Length: 41865824

             SourceID: 060a2b340101010101010f00-13-000000-{ 8f47bea9-2198-3c2b-8a95-f08f11cd5520 }

             SourceMobSlotID: 1

             StartTime: 0

        PhysicalTrackNumber: 369164801

        EditRate: { 48000/1 }

        Origin: 0

     LastModified: Apr 22, 2019 15:12:48.00 GMT

     CreationTime: Apr 22, 2019 15:12:39.00 GMT

     EssenceDescription: 

       [ PCMDescriptor ]

       SampleRate: { 48000/1 }

       Length: 41865823

       ContainerFormat: MXF

       QuantizationBits: 24

       Locked: False

       AudioSamplingRate: { 48000/1 }

       AudioRefLevel: -18

       ElectroSpatial: ElectroSpatialFormulation_SingleChannelMode

       Channels: 1

       AverageBPS: 144000

       BlockAlign: 3

       SequenceOffset: 0

       DialNorm: 27

  • Wed, Jun 12 2019 11:14 AM In reply to

    Re: Media Composer 18.9 audio only clips causing problems with AMT2 (PCM is sometimes one sample less than clip duration requires)

    Update to this issue. Resolved with editor update from 18.9 to 18.11.

    We loaded Media Composer 18.11 at our facility - making the same length mix down clip with this newer editor version resovles the issue. THe duration in the audio descriptor is no longer less than the expected length.    Tested several known mixdown lengths that caused the issue with 18.9 and all are correct with 18.11.   Will advise customer to update editor version.

    Rich

     

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