If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT, but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly small chunks of data returned from the callback).
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If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT, but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly small chunks of data returned from the callback).