Methods and systems for scalable video chunking
Methods and systems for creating and retrieving scalable media files using a chunking model. A plurality of network abstraction layer (NAL) units representing a scalable media presentation are grouped into a plurality of video chunks wherein each chunk represents only the NAL units of one layer and a specific time period. The plurality of video chunks are then stored in one or more scalable media files along with indexing information which provides information for retrieving the NAL units from each video chunk. In this manner, a client can request only the video chunks (and thus NAL units) that it needs or wants to achieve a specific bandwidth.
1. A method for generating a scalable media file, the method comprising:
(a) providing a plurality of network abstraction layer (NAL) units representing a scalable media presentation, each NAL unit being associated with one layer of a plurality of layers;
(b) grouping the plurality of NAL units into a plurality of video chunks, each video chunk comprising the NAL units associated with only one layer for a specific time period of the scalable media presentation;
(c) generating indexing information for each video chunk, the indexing information providing information for extracting the plurality of NAL units from the video chunk; and
(d) storing the plurality of video chunks and the associated indexing information in at least one scalable media file.
2. The method of claim 1 , further comprising:
(e) generating retrieval information for the at least one scalable media file, the retrieval information providing information for retrieving the video chunks from the at least one scalable media file; and
(f) storing the retrieval information in the at least one scalable media file.
3. The method of claim 2 , wherein the at least one scalable media file is comprised of a plurality of bytes and the retrieval information links each video chunk to a byte range of the at least one scalable media file.
4. The method of claim 3 , wherein:
(A) the retrieval information comprises a byte range index and a plurality of byte range boxes;
(B) each byte range box specifies a plurality of byte ranges associated with a specific time period, each byte range corresponding to one video chunk of the plurality of video chunks; and
(C) the byte range index links each byte range with one layer of the plurality of layers.
5. The method of claim 1 , further comprising:
(e) generating retrieval information for the at least one scalable media file, the retrieval information providing information for retrieving the video chunks from the at least one scalable media file; and
(f) storing the retrieval information in a separate scalable media file from the plurality of video chunks.
6. The method of claim 1 , further comprising:
(e) providing a first plurality of audio samples associated with the plurality of NAL units, the first plurality of audio samples being associated with a first audio quality;
(f) grouping the first plurality of audio samples into a plurality of audio chunks, each audio chunk representing the first audio samples over a specific time period of the scalable media presentation; and
(g) storing the audio chunks in the at least one scalable media file.
7. The method of claim 6 , further comprising:
(g) providing a second plurality of audio samples associated with the plurality of NAL units, the second plurality of audio samples being associated with a second audio quality;
(h) grouping the second plurality of audio samples into a plurality of audio chunks, each audio chunk comprising the second audio samples for a specific time period of the scalable media presentation; and
(i) storing the audio chunks in the at least one scalable media file.
8. The method of claim 1 , wherein the indexing information comprises a decoding order number for each NAL unit of the associated video chunk.
9. The method of claim 1 , wherein the indexing information comprises an offset and a length for each NAL unit of the associated video chunk.
10. The method of claim 1 , further comprising:
(e) generating mapping information for each time period of the scalable media presentation, each mapping information providing information for retrieving the video chunks for the time period; and
(f) linking each mapping information with at least one video chunk of a preceding time period; and
(g) storing the mapping information in the at least one scalable media file.
11. The method of claim 10 , wherein each mapping information is stored in the at least one scalable media file as part of the at least one video chunk of the preceding time period.
12. The method of claim 1 , further comprising updating the at least one scalable media file with additional video chucks as additional NAL units are provided.
13. The method of claim 1 , wherein the plurality of video chunks are stored in a single scalable media file.
14. The method of claim 13 , wherein the plurality of video chunks are stored in the scalable media file in a contiguous manner, the order of the video chunks being based on inter-dependencies between the layers.
15. The method of claim 1 , wherein the first NAL unit of each video chunk is an I-frame.