Information signal editing apparatus and editing system

An information signal editing apparatus in which a plurality of information signals having synchronization information are entered asynchronously and which edits at least one of the plurality of entered information signals, comprising:

• synchronization signal detecting means for detecting said synchronization information from said plurality of entered information signals;
• editing means for performing editing processing on at least one of said plurality of entered information signals based on said synchronization information detected by said synchronization information detecting means;
• wherein said synchronization information detecting means controls the editing processing of said editing means based on time information included in said synchronization information for use in the editing processing and has control means for determining whether said editing processing is completed within a processing time specified based on said time information;
• and
• wherein said control means generates a control signal for making said editing means perform alternate arithmetic processing if said control means determines that said editing processing is not completed within the specified processing time.