ecw to shp conversion is most likely related to export between two graphics formats that are often used for vectors or non-topological geometry data (shape files), in this particular case between ECW Format (Enhanced Compressed Wavelet) and ESRI ArcView shape files.
Standard graphics editors or converters are not sufficient in this case and you have to rely on one of the GIS solutions (for example GME DESKTOP) for this. You can even find dedicated converters for such exports, some might be even available as online apps.
Updated: November 6, 2023