From video source material, one generates a first coded signal using a combination of inter-frame and intra-frame coding, in which intra-coded pictures are forced to occur at least once in each of successive first set time periods. A second coded version of the same source has intra-coded pictures occurring wholly or mainly at times determined by recognition of scene changes in the video source material. In response to a command for streaming, or resumption of streaming, of said video source material, (perhaps following trick-play), firstly the first coded signal is streamed, commencing with an intra-coded picture. Then, at a point coinciding with an intra-coded picture of the second coded signal, one ceases streaming of the first coded signal and instead streams the second coded signal, commencing with that intra-coded picture.