In commercial hybrid videos, the interlaced, progressive and pulldown video frames coexist in the same stream. These frames can be identified only by the presence of the combing artefacts caused due to the inter-field motion. A difficulty with existing inter-field quantifiers is that they require an adaptive threshold owing to the varying spatial and temporal characteristics of the frames in the video sequence. Proposed is a robust inter-field quantifier, that is unique and consistent across different standards, resolutions and quality by providing a stable threshold cutoff and dynamic range. The quantifier shows good stability and is also superior to existing methods in terms of performance.