Watermarking and Fingerprinting Digital Content Using Alternative Blocks to Embed Information

Abstract

A method of embedding information in digital content representing media streams. The method includes (1) selecting a set of locations within that digital content reprensenting the media stream to embed information, (2) selecting a set of possible alterations to make at those locations, and (3) making a subset of the possible alterations. The set of locations and possible alterations is herein sometimes called a “watermark.” The subset of actual alterations that are made is herein sometimes called a “fingerprint.” The method determines a set of locations at which there are alternative versions of digital content representing the same media stream, such as one being the original and one being an alternative version of the same digital content, herein sometimes called the “original movie” and the “alt-movie,” or herein sometimes called the “original block” and the “alt-block” for a particular block in the digital content representing the media stream.

1 . A computer-implemented method, comprising:
 determining, for digital content, a watermark including locations and alternate blocks, at the locations for embedding data, wherein replacement of an original block with an alternate block embeds more than zero bits of the data in the digital content;   based at least in part on the alternate blocks, determining actual alterations in the digital content; and   based at least in part on the actual alterations in the digital content, extracting bits from the digital content,   wherein the alternate blocks contain two or more alterations, wherein the alterations if made individually result in a changed block length for the original block, but each alternate block has the same block length as the corresponding original block.   
     
     
         2 . The method of  claim 1 , wherein the alternate blocks preserve packetization of the digital content. 
     
     
         3 . The method of  claim 1 , wherein the determining actual alterations in the digital content includes identifying at least one alteration that individually would change the length of a packet. 
     
     
         4 . A device, comprising:
 a network interface over which digital content can be injected into a network;   a processor;   a memory storing the digital content and storing instructions executable by the processor, the instructions when executed cause the processor to:
 (a) select locations in the digital content for embedding data; and 
 (b) select alternate blocks to replace original blocks at the selected locations, wherein replacement of an original block with an alternate block embeds more than zero bits of the data in the digital content, and wherein the locations and the alternate blocks together form a watermark for the digital content, 
   wherein the alternate blocks contain two or more alterations, wherein the alterations if made individually result in a changed block length for the original block, but each alternate block has the same block length as the corresponding original block.   
     
     
         5 . The device of  claim 4 , wherein the alternate blocks preserve packetization of the digital content. 
     
     
         6 . The device of  claim 4 , wherein the digital content is encoded using variable length codes, and wherein at least one alternate block uses different variable length codes than the corresponding original block. 
     
     
         7 . The device of  claim 4 , wherein each alternate block does not change the presentation of the corresponding original block by more than a predefined amount. 
     
     
         8 . The device of  claim 7 , wherein the predefined amount is based at least in part on a maximum level change and a maximum quantization scale. 
     
     
         9 . The device of  claim 8 , wherein the maximum level change is plus or minus one, and wherein the maximum quantization scale is twenty-four. 
     
     
         10 . A computer readable medium storing instructions executable by a processor, the instructions when executed cause to the processor to:
 accept data corresponding to digital content;   accept watermark data, wherein the watermark data includes locations within the digital content, and wherein the watermark data includes alternate blocks at the locations of the digital content; and   based on at least a portion of the watermark data, alter the digital content,   wherein the alternate blocks contain two or more alterations, wherein the alterations if made individually result in a changed block length for the original block, but each alternate block has the same block length as the corresponding original block.