Preventing Trick Modes in DVR Streams by Removing I-Frames
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Solution Overview
Problem
Current digital video recording and network personal video recorder systems allow users to easily fast-forward through advertisements and other content, which can reduce revenue for content providers and advertisers, and may not effectively prevent trick mode functionality on uncontrolled set-top boxes.
Innovation Solution
The method involves removing substantially complete frames, such as I-frames, from specific portions of digitally compressed audiovisual assets, like advertisements, and streaming only intermediate frames to prevent trick play, using techniques like MPEG-2 or H.264/MPEG-4/AVC compression, and employing embedded cue tones to delimit these portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If trick mode functionality is allowed in DVR/NDVR systems, then user convenience and ease of operation are improved, but content provider revenue and control over content viewing are worsened
Solution Approach 1:
The patent extracts and removes I-frames (intra-coded pictures) from the video stream during specific time periods when trick mode prevention is desired. By taking out these key reference frames, the system prevents users from fast-forwarding or rewinding through protected content segments while maintaining normal playback functionality.
Solution Approach 2:
The system performs preliminary identification and marking of time periods in the content where trick mode should be prevented. Metadata is prepared in advance indicating which segments require protection, allowing the DVR/NDVR system to selectively remove I-frames from those specific periods before playback occurs.
2Reliability
If I-frames are removed from video streams to prevent trick modes, then trick mode prevention effectiveness is improved, but video decoding complexity and potential playback issues are worsened
Solution Approach 1:
The patent applies different frame structures to different time periods within the same video content. During protected periods, I-frames are removed to prevent trick modes, while during unprotected periods, normal frame structures with I-frames are maintained. This local differentiation allows trick mode prevention without compromising overall video playback reliability.
Solution Approach 2:
The system dynamically adjusts the video stream composition based on the current playback position and the protected time periods identified in the metadata. The DVR/NDVR selectively removes I-frames only from protected segments while maintaining them in non-protected segments, creating a dynamically adapted stream that prevents trick modes where needed without causing decoding issues elsewhere.
Data Source
AI summary
Trick modes are substantially prevented during DVR and NDVR content by obtaining an audiovisual asset that is digitally compressed in accordance with a compression technique employing at least a plurality of substantially complete frames and a plurality of substantially intermediate frames, substantially removing the plurality of substantially complete frames from a portion of the asset for which trick play is to be substantially prevented, and streaming the asset, with the plurality of substantially complete frames substantially removed from the portion thereof, to a user thereof.