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 receiving a scalable media presentation over a communications network, the method comprising:
(a) transmitting a request from a client device to a server for a scalable media presentation;
(b) receiving retrieval information from the server in response to the request for the scalable media presentation, the retrieval information providing information for retrieving a plurality of video chunks associated with the scalable media presentation, each video chunk comprising network abstraction layer (NAL) units associated with only one layer of a plurality of layers for a specific time period of the scalable media presentation;
(c) selecting a time period of the scalable media presentation to retrieve;
(d) selecting at least one video chunk associated with the selected time period based on the retrieval information;
(e) transmitting a request to the server for the at least one video chunk; and
(f) receiving the at least one video chunk and indexing information associated with the at least one video chunk from the server, the indexing information providing information for extracting the plurality of NAL units from the at least one video chunk; and
(g) extracting the NAL units from the at least one video chunk based on the indexing information associated with the at least one video chunk.
2. The method of claim 1 , further comprising:
(h) selecting a subsequent time period of the scalable media presentation to retrieve; and
(i) repeating steps (d) to (h) until there are no more time periods of the scalable media presentation to retrieve.
3. The method of claim 1 , wherein the indexing information comprises an offset and a length for each NAL unit in the associated video chunk, and step (g) comprises extracting each NAL unit from the at least one video chunk using the offset and length.
4. The method of claim 1 , wherein the indexing information comprises a decoding order number for each NAL unit in the associated video chunk; and the method further comprises ordering the extracted NAL units based on the decoding order numbers.
5. The method of claim 1 , wherein the retrieval information links each video chunk to a specific byte range of an associated scalable media file; and the request for the at least one video chunk is a byte range request based on the retrieval information.
6. The method of claim 5 , wherein:
(A) the retrieval information comprises a byte range index and at least one byte range box;
(B) the at least one byte range box specifies a plurality of byte ranges associated with a specific time period, each byte range being associated with one video chunk; and
(C) the byte range index links each of the plurality of byte ranges with one layer of the plurality of layers.
7. The method of claim 1 , wherein:
(A) the at least one video chunk comprises mapping information for retrieving the video chunks of a subsequent time period; and
(B) the method further comprises selecting at least one second video chunk to retrieve based on the mapping information of the at least one video chunk received.
8. The method of claim 1 , wherein the retrieval information further provides information for retrieving a plurality of audio chunks, each audio chunk comprising audio samples for a specific time period of the scalable media presentation; and the method further comprises:
(h) selecting at least one audio chunk associated with the selected time period based on the retrieval information;
(i) transmitting a request to the server for the selected at least one audio chunk;
(j) receiving the at least one audio chunk and indexing information associated with the at least one audio chunk; and
(k) extracting the audio samples from the at least one audio chunk based on the indexing information associated with the at least one audio chunk.
9. The method of claim 1 , wherein the server is a web server and the request for the at least one video chunk is a HTTP byte range request.