Selective encryption to enable trick play
First Claim
1. A method of selectively encrypting digital video content, comprising;
- receiving a plurality of packets containing the digital video content;
selecting packets from the plurality of packets for encryption according to a selection criterion, wherein the selection criterion is explicitly based at least in part upon the presence or absence of a start of frame (SOF) header in the selected packets, and wherein the selected packets exclude certain packets containing SOF headers;
encrypting the selected packets; and
retaining the certain packets containing the SOF headers unencrypted to form selectively encrypted digital video content.
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Abstract
Certain embodiments consistent with the present invention involve a method of selectively encrypting and decoding digital video content. Certain of the packets are selected for encryption according to a selection criterion, wherein the selected packets exclude packets containing start of frame (SOF) headers. The selected packets are encrypted while retaining the packets containing the SOF headers unencrypted to form selectively encrypted digital video content. In decoding selectively encrypted digital video content, offsets are calculated for at least one of I frames and P frames from the SOF headers and the calculated offsets are stored as an offset table. The offset table can then be accessed to enable trick play of the selectively encrypted digital video content.
382 Citations
32 Claims
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1. A method of selectively encrypting digital video content, comprising;
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receiving a plurality of packets containing the digital video content; selecting packets from the plurality of packets for encryption according to a selection criterion, wherein the selection criterion is explicitly based at least in part upon the presence or absence of a start of frame (SOF) header in the selected packets, and wherein the selected packets exclude certain packets containing SOF headers; encrypting the selected packets; and retaining the certain packets containing the SOF headers unencrypted to form selectively encrypted digital video content. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of decoding selectively encrypted digital video content comprising:
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receiving the selectively encrypted digital video content, wherein the selectively encrypted digital video content has certain unencrypted packets containing start of frame (SOF) headers, wherein the certain unencrypted packets were selected based upon a selection criterion that is explicitly based at least in part upon the presence or absence of a start of an SOF header in the selected packets; calculating offsets for at least one of I frames and P frames from the SOF headers; and storing the calculated offsets as an offset table. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A decoder for decoding selectively encrypted digital video content, comprising:
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a receiver that receives the selectively encrypted digital video content, wherein the selectively encrypted digital video content has unencrypted packets containing start of frame (SOF) headers; wherein the certain unencrypted packets were selected based upon a selection criterion that is explicitly based at least in part upon the presence or absence of a start of an SOF header in the selected packets; an offset calculator tat calculates offsets for at least one of I frames and P frames from the SOF headers; and means for storing the calculated offsets as an offset table. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. A selective encryption encoder for selective encryption of digital video content, comprising;
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means for receiving a plurality of packets containing the digital video content; a programmed processor that selects packets for encryption according to a selection criterion, wherein the selected packets exclude certain packets containing start of frame (SOF) headers; wherein the selection criterion is explicitly based at least in part upon the presence or absence of a SOF header in the selected packets; and an encrypter for encrypting the selected packets while retaining the certain packets containing the SOF headers unencrypted to form selectively encrypted digital video content. - View Dependent Claims (29, 30, 31, 32)
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Specification