# US 7,151,833 B2 · Selective encryption to enable trick play

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 7,151,833 B2
- Document ID: US7151833B2
- Status: Granted
- Kind: B2
- Application number: 10/391,940
- Filed: 2003-03-19
- Published: 2004-03-11
- Granted: 2006-12-19
- Earliest claimed: 2002-09-09
- Assignees: Sony Corporation; Sony Electronics Inc.
- Inventors: Brant L. Candelore; Tom Poslinski
- Web page: https://patentgrep.com/patent/US7151833B2

## CPC

- H04N 21/434: Disassembling of a multiplex stream, e.g. demultiplexing audio and video streams, extraction of additional data from a video stream; Remultiplexing of multiplex streams; Extraction or processing of SI; Disassembling of packetised elementary stream {(demultiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00)}
- H04N 5/783: Adaptations for reproducing at a rate different from the recording rate
- H04N 5/913: for scrambling {; for copy protection}
- H04N 7/163: {by receiver means only}
- H04N 7/165: {Centralised control of user terminal (subsequent to an upstream request signal H04N7/17345); Registering at central (by two-way working H04N7/17309)}
- H04N 7/1675: {Providing digital key or authorisation information for generation or regeneration of the scrambling sequence (pseudo-random number generators in general G06F7/58)}
- H04N 7/52: Systems for transmission of a pulse code modulated video signal with one or more other pulse code modulated signals, e.g. an audio signal or a synchronizing signal (assembling of a multiplex stream by combining a video stream with other content or additional data, remultiplexing of multiplex streams, insertion of stuffing bits into the multiplex stream, assembling of a packetised elementary stream at server side H04N21/236; disassembling of a multiplex stream, remultiplexing of multiplex streams, extraction or processing of Service Information, disassembling of packetised elementary stream at client side H04N21/434)
- H04N 9/7925: {for more than one standard}
- H04N 21/234345: {the reformatting operation being performed only on part of the stream, e.g. a region of the image or a time segment}
- H04N 21/23439: {for generating different versions}
- H04N 21/2347: involving video stream encryption
- H04N 21/23476: {by partially encrypting, e.g. encrypting the ending portion of a movie}
- H04N 21/235: Processing of additional data, e.g. scrambling of additional data or processing content descriptors
- H04N 21/236: Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream {(multiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00)}
- H04N 21/238: Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams {(hybrid fiber coaxial [HFC] networks for downstream channel allocation for video distribution H04L12/2801; flow control in packet networks H04L47/10; real-time communication protocols in data switching networks H04L65/00; scheduling or organising the servicing of application requests H04L67/60)}
- H04N 21/25435: {involving characteristics of content or additional data, e.g. video resolution or the amount of advertising}
- H04N 21/25833: {involving client hardware characteristics, e.g. manufacturer, processing or storage capabilities (allocation of resources considering hardware capabilities in multiprogramming arrangements G06F9/5044; allocation of resources considering software capabilities in multiprogramming arrangements G06F9/5055)}
- H04N 21/26606: {for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM] (arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14)}
- H04N 21/2668: Creating a channel for a dedicated end-user group, e.g. insertion of targeted commercials based on end-user profiles {(information retrieval from the Internet by querying with filtering and personalisation G06F16/9535; arrangements for replacing or switching information during the broadcast H04H20/10; push services over packet-switching network H04L12/1859; adaptation of message content in packet-switching networks H04L51/063)}
- H04N 21/4331: {Caching operations, e.g. of an advertisement for later insertion during playback}
- H04N 21/4333: {Processing operations in response to a pause request}
- H04N 21/435: Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
- H04N 21/43607: {Interfacing a plurality of external cards, e.g. through a DVB Common Interface [DVB-CI]}
- H04N 21/440245: {the reformatting operation being performed only on part of the stream, e.g. a region of the image or a time segment}
- H04N 21/440281: {by altering the temporal resolution, e.g. by frame skipping (television signal recording using magnetic recording on tape for reproducing at a rate different from the recording rate H04N5/783)}
- H04N 21/44055: {by partially decrypting, e.g. decrypting a video stream that has been partially encrypted}
- H04N 21/458: Scheduling content for creating a personalised stream, e.g. by combining a locally stored advertisement with an incoming stream; Updating operations, e.g. for OS modules {; time-related management operations (arrangements for replacing or switching information during the broadcast or during the distribution H04H20/10)}
- H04N 21/4623: Processing of entitlement messages, e.g. ECM [Entitlement Control Message] or EMM [Entitlement Management Message] {(arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14)}
- H04N 21/47202: {for requesting content on demand, e.g. video on demand}
- H04N 21/63345: {by transmitting keys (key distribution for secret or secure communication H04L9/08; network support of key management H04L63/06)}
- H04N 21/812: {involving advertisement data (advertising per se G06Q30/02)}
- H04N 21/835: Generation of protective data, e.g. certificates {(protecting software against unauthorised usage in a vending or licensing environment G06F21/10)}
- H04N 21/8455: {involving pointers to the content, e.g. pointers to the I-frames of the video stream}
- H04N 2005/91364: {the video signal being scrambled}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## 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.

## Claims

### 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.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising storing the selectively encrypted digital video content on an electronic storage medium.

### Claim 3 (depends on 1)

The method according to claim 1, further comprising transmitting the selectively encrypted digital video content to a receiver.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the selection criterion comprises selection of all packets except those packets containing the SOF header.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the selection criterion comprises selection of packets except those certain packets containing the SOF header where the selected packets represent less than all of the remaining packets excluding those certain packets containing the SOF header.

### Claim 6 (depends on 1)

The method according to claim 1, wherein at least one packet containing an SOF header is not one of the certain packets containing a SOF header and is encrypted.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the certain packets containing the SOF headers comprise I frame packets.

### Claim 8 (depends on 1)

The method according to claim 1, carried out on a programmed processor.

### Claim 9 (depends on 1)

An electronic computer readable storage medium storing instructions that, when executed on a programmed processor, carry out the method of selectively encrypting digital video cement according to claim 1.

### Claim 10

A method of decoding selectively encrypted digital video content comprising:
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.

### Claim 11 (depends on 10)

The method according to claim 10, further comprising accessing the offset table to enable trick play of the selectively encrypted digital video content.

### Claim 12 (depends on 10)

The method according to claim 10, wherein the selectively encrypted digital video content is stored on an electronic storage medium.

### Claim 13 (depends on 10)

The method according to claim 10, wherein the selectively encrypted digital video content is transmitted from a content provider to a receiver.

### Claim 14 (depends on 10)

The method according to claim 10, wherein the selectively encrypted digital video content is fully encrypted except for certain packets containing SOF headers.

### Claim 15 (depends on 10)

The method according to claim 10, wherein the selectively encrypted digital video content comprises the certain unencrypted packets containing SOF headers, encrypted packets containing SOF headers, packets that do not contain SOF headers that are encrypted, and packets that do not contain SOF headers that are unencrypted.

### Claim 16 (depends on 10)

The method according to claim 10, wherein at least one packet containing an SOF header is not one of the certain packets containing a SOF header and is encrypted.

### Claim 17 (depends on 10)

The method according to claim 10, wherein the certain packets containing the SOF headers comprise I frame packets.

### Claim 18 (depends on 10)

The method according to claim 10, carried out on a programmed processor.

### Claim 19 (depends on 10)

An electronic storage medium storing instructions that, when executed on a programmed processor, carry out the method of decoding selectively encrypted digital video content according to claim 10.

### Claim 20

A decoder for decoding selectively encrypted digital video content, comprising:
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.

### Claim 21 (depends on 20)

The decoder according to claim 20, further comprising means for accessing the offset table to enable trick play of the selectively encrypted digital video content.

### Claim 22 (depends on 20)

The decoder according to claim 20, wherein, the selectively encrypted digital video content is stored on an electronic storage medium.

### Claim 23 (depends on 20)

The decoder according to claim 20, wherein the selectively encrypted digital video content is transmitted from a content provider to a receiver.

### Claim 24 (depends on 20)

The decoder according to claim 20, wherein the selectively encrypted digital video content is fully encrypted except for the certain packets containing the SOF header.

### Claim 25 (depends on 20)

The decoder according to claim 20, wherein the selectively encrypted digital video content comprises unencrypted packets containing SOF headers, encrypted packets containing SOF headers that are encrypted, packets that do not contain SOF headers that are encrypted, and packets that do not contain SOF headers that are unencrypted.

### Claim 26 (depends on 20)

The decoder according to claim 20, wherein the offset calculator is implemented by a programmed processor.

### Claim 27 (depends on 20)

The decoder according to claim 20, wherein the offset table is stored in an electronic storage medium.

### Claim 28

A selective encryption encoder for selective encryption of digital video content, comprising;
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.

### Claim 29 (depends on 28)

The encoder according to claim 28, further comprising an electronic storage medium for storing the selectively encrypted digital video content.

### Claim 30 (depends on 28)

The encoder according to claim 28, further comprising a transmitter for transmitting the selectively encrypted digital video content to a receiver.

### Claim 31 (depends on 28)

The encoder according to claim 28, wherein the selection criterion comprises selection of all packets except those containing the SOF header.

### Claim 32 (depends on 28)

The encoder according to claim 28, wherein the selection criterion comprises selection of certain packets except those containing the SOF header where the certain packets represent less than all of the packets that do not contain the SOF header.