A video data processing method that generates a trick play stream with an altered reproducing speed and reproducing direction from a video stream coded using frame-to-frame prediction, comprising: a step of selectively extracting intra-frame coded pictures from the video stream, conforming to the speed and direction of the trick play stream to be reproduced; an extraction step of extracting coding parameters of the extracted intra-frame coded pictures; a modification step of modifying the coding parameters according to said speed and direction; and a generating step of generating the trick play stream by generating repeat pictures displaying content identical to the extracted intra-frame coded pictures and adding the repeat pictures following the intra-frame coded pictures with the modified coding parameters, the intra-frame coded pictures with the modified coding parameters being selected in their order of data transfer according to said reproducing speed and reproducing direction, wherein: the extraction step extracts a VBV delay parameter of the extracted intra-frame coded pictures; and the modification step modifies the VBV delay parameter so that the transferred trick play stream does not produce a failure of the decoder buffer, characterised in that the modification step determines a VBV delay of the trick play stream, according to the following equation: τ T 0 = a N / a T × τ N 0 where aN denotes a transfer rate of the video stream, a T denotes a transfer rate of the trick play stream, τ N0 denotes a VBV delay of the first picture of the video stream, and τ T0 denotes the VBV delay of the trick play stream. a step of selectively extracting intra-frame coded pictures from the video stream, conforming to the speed and direction of the trick play stream to be reproduced; an extraction step of extracting coding parameters of the extracted intra-frame coded pictures; a modification step of modifying the coding parameters according to said speed and direction; and a generating step of generating the trick play stream by generating repeat pictures displaying content identical to the extracted intra-frame coded pictures and adding the repeat pictures following the intra-frame coded pictures with the modified coding parameters, the intra-frame coded pictures with the modified coding parameters being selected in their order of data transfer according to said reproducing speed and reproducing direction, wherein: the extraction step extracts a VBV delay parameter of the extracted intra-frame coded pictures; and the modification step modifies the VBV delay parameter so that the transferred trick play stream does not produce a failure of the decoder buffer, characterised in that the modification step determines a VBV delay of the trick play stream, according to the following equation: τ T 0 = a N / a T × τ N 0 where aN denotes a transfer rate of the video stream, a T denotes a transfer rate of the trick play stream, τ N0 denotes a VBV delay of the first picture of the video stream, and τ T0 denotes the VBV delay of the trick play stream. the extraction step extracts a VBV delay parameter of the extracted intra-frame coded pictures; and the modification step modifies the VBV delay parameter so that the transferred trick play stream does not produce a failure of the decoder buffer, characterised in that the modification step determines a VBV delay of the trick play stream, according to the following equation: τ T 0 = a N / a T × τ N 0 where aN denotes a transfer rate of the video stream, a T denotes a transfer rate of the trick play stream, τ N0 denotes a VBV delay of the first picture of the video stream, and τ T0 denotes the VBV delay of the trick play stream. aN denotes a transfer rate of the video stream, a T denotes a transfer rate of the trick play stream, τ N0 denotes a VBV delay of the first picture of the video stream, and τ T0 denotes the VBV delay of the trick play stream.