Transcoded images for improved trick play
View Patent ↗A method and apparatus are provided for facilitating processing of images contained in an encoded video stream wherein a plurality of non-intra coded images are transcoded into intra-coded images (I-images). The transcoded I-images are then used to facilitate trick mode playback, such as reverse playback, fast reverse playback or fast forward playback. In addition, an image sequence window is defined and transcoded I-images which fall outside of the image sequence window are deleted from a memory.
1. A method for facilitating processing of images for trick play contained in an encoded video stream comprising:
transcoding a plurality of non-intra coded images into intra-coded images (I-images);
storing a plurality of said transcoded I-images on a data storage;
after said storing, defining a sliding image sequence window containing a plurality of recently transcoded I-images, said sliding image sequence window tracking normal playback of said encoded video stream; and
storing only transcoded I-images which fall within said sliding image sequence window by deleting, from said data storage, ones of said stored transcoded I-images which fall outside said sliding image sequence window.
2. The method of claim 1 , wherein said transcoding comprises exclusively transcoding predictive images (P-images).
3. The method of claim 1 , wherein said transcoding comprises exclusively transcoding bidirectional images (B-images).
4. The method of claim 1 , wherein said transcoding comprises transcoding predictive images (P-images) and bidirectional images (B-images).
5. The method of claim 1 , further comprising:
during fast playback trick mode, decoding a combination of said transcoded I-images and originally coded images, said transcoded I-images being used as references for predicting respective ones of said originally coded images.
6. The method of claim 1 , wherein said step of transcoding the non-intra coded images into I-images is performed during normal playback of said encoded video stream.
7. The method of claim 1 , further comprising decoding said transcoded I-images during trick mode playback of said encoded video stream.
8. The method of claim 7 , wherein said trick mode playback is reverse trick play.
9. The method of claim 7 , wherein said trick mode playback is fast reverse trick play.
10. The method of claim 7 , wherein said trick mode playback is fast forward trick play.
11. An apparatus for facilitating processing of images for trick play contained in an encoded video stream comprising:
an encoder for transcoding a plurality of non-intra coded images into intra- coded images (I-images);
a data storage means for storing a plurality of said transcoded I-images;
after said storing, a processor for defining a sliding image sequence window containing a plurality of recently transcoded I-images, said sliding image sequence window tracking normal playback of said encoded video stream; and
said processor for deleting, from said data storage means, ones of said stored transcoded I-images which fall outside said sliding image sequence window to thereby store only transcoded I-images which fall within said sliding image sequence window.
12. The apparatus of claim 11 , wherein said encoder exclusively transcodes predictive images (P-images).
13. The apparatus of claim 11 , wherein said encoder exclusively transcodes bidirectional images (B-images).
14. The apparatus of claim 11 , wherein said encoder transcodes predictive images (P-images) and bidirectional images (B-images).
15. The apparatus of claim 11 , wherein during fast playback trick mode, a decoder decodes a combination of said transcoded I-images and originally coded images, said transcoded I-images being used as references for predicting ones of said originally coded images.
16. The apparatus of claim 11 , wherein said encoder transcodes the non-intracoded images into I-images during normal playback of said encoded video stream.
17. The apparatus of claim 11 , wherein a decoder decodes said transcoded I-images during trick mode playback of said encoded video stream.
18. The apparatus of claim 11 , wherein said apparatus comprises a personal video recorder.