An opportunistic frame cache system comprising at least a processor and a cache memory adapted to perform all steps of an opportunistic frame cache method comprising: identifying source frames to be transcoded in response to a preview request for a sampling segment ; transcoding a source frame to generate a transcoded frame ; transcoding a set of the identified source frames prior to transcoding source frames that are not responsive to any preview request for a sampling segment ; generating a preview segment comprising one or more preview frames wherein each preview frame of the preview segment is comprised of at least one transcoded frame and wherein the preview segment is responsive to a received preview request ; outputting a preview segment ; identifying the preview frame in a preview segment that is currently being output ; determining that there is insufficient time for at least one source frame of the set of the identified source frames to be transcoded at a first time; modifying the set of the identified source frames to transcode in response to the preview request when it is determined that there is insufficient time for the at least one source frame of the set of the identified source frames to be transcoded, identifying a second set of source frames to transcode in response to a second preview request for a second sampling segment when at least one source frame of the set of the identified source frames to transcode for a prior preview request has not yet been transcoded; changing the set of source frames to transcode to comprise the second set of source frames identified to be transcoded in response to the second preview request wherein the set of source frames to transcode is changed before at least one source frame of the set of the identified source frames to transcode for a prior preview request is transcoded; and transcoding the second set of source frames prior to transcoding source frames that are not responsive to a preview request for a sampling segment . identifying source frames to be transcoded in response to a preview request for a sampling segment ; transcoding a source frame to generate a transcoded frame ; transcoding a set of the identified source frames prior to transcoding source frames that are not responsive to any preview request for a sampling segment ; generating a preview segment comprising one or more preview frames wherein each preview frame of the preview segment is comprised of at least one transcoded frame and wherein the preview segment is responsive to a received preview request ; outputting a preview segment ; identifying the preview frame in a preview segment that is currently being output ; determining that there is insufficient time for at least one source frame of the set of the identified source frames to be transcoded at a first time; modifying the set of the identified source frames to transcode in response to the preview request when it is determined that there is insufficient time for the at least one source frame of the set of the identified source frames to be transcoded, identifying a second set of source frames to transcode in response to a second preview request for a second sampling segment when at least one source frame of the set of the identified source frames to transcode for a prior preview request has not yet been transcoded; changing the set of source frames to transcode to comprise the second set of source frames identified to be transcoded in response to the second preview request wherein the set of source frames to transcode is changed before at least one source frame of the set of the identified source frames to transcode for a prior preview request is transcoded; and transcoding the second set of source frames prior to transcoding source frames that are not responsive to a preview request for a sampling segment . <EOS>