The 1080p50 and 1080p60 standards are ideal for use as studio acquisition formats, however a bit-rate of 3 Gb/s is required to transport them in an uncompressed form. A compression method is described which makes it possible to encode a 1080p50 or 1080p60 signal into a format that is compatible with the 1080i standard and suitable for transport via HD-SDI at 1.5 Gb/s. A novel feature is that the compressed signal is recognisable when displayed as 1080i, for ease of monitoring and identification. When that feature is not required a compression ratio of 2.5:1 is achievable.