mxfvanc: Handle empty ANC essence
Not having any actual ANC is totally fine and common usage with several MXF variants.
In order to properly advance the streams, we output an empty buffer is no actual content was in the ANC Essence Element.
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Not having any actual ANC is totally fine and common usage with several MXF variants.
In order to properly advance the streams, we output an empty buffer is no actual content was in the ANC Essence Element.