Streaming media technology includes a back buffer configured to begin at a stream frame most recently played by the streaming media player. The back buffer continues, for each played frame of the stream, for a length determined by a nominal fill and an offset. In some embodiments, the offset is determined in runtime. In some embodiments the runtime-determined offset is determined by the position of a keyframe in the vicinity of the nominal fill. The keyframe in the vicinity of the nominal fill can be a keyframe next earlier, next later, or nearest in the stream to the location of the nominal fill.