Encoding of modified video

1. A method of processing a video stream comprising:

receiving a first set of input image frames comprising image data originating from a first source of input image frames;

receiving a second set of input image frames comprising image data originating from a second source of input image frames, wherein the second set of input image frames includes modifications or changes relative to the first set of image frames;

encoding the first set of input image frames and the second set of input image frames into, respectively, a first set of encoded image frames and a second set of encoded image frames, forming a combined video stream, wherein an encoded image frame of the first set of encoded image frames exclusively references one or more other encoded image frames of the first set of encoded image frames, and wherein an encoded image frame of the second set of encoded image frames references both an encoded image frame of the first set of encoded image frames and another encoded image frame of the second set of encoded image frames;

designating the first set of encoded image frames as image frames not to be displayed or designating the second set of encoded image frames as image frames to be displayed;

signing, using a first key, a first signing group comprising one or more encoded image frames of the first set of encoded image frames, wherein the first key pertains to the first source of input image frames; and

signing, using a second key, a second signing group comprising one or more encoded image frames of the second set of encoded image frames, wherein the second key pertains to the second source of input image frames.

2. The method according to claim 1 , wherein the second signing group further comprises one or more encoded image frames of the first set of encoded image frames referred to by an encoded image frame of the second set of encoded image frames.

3. The method according to claim 1 , further comprising:

receiving a third set of input image frames comprising image data originating from a third source of input image frames, wherein the encoding further comprises encoding the third set of input image frames into a third set of encoded image frames, forming part of the combined video stream, wherein an encoded image frame of the third set of encoded image frames references both an encoded image frame of the first set of encoded image frames and another encoded image frame of the third set of encoded image frames, said method further comprising:

signing, using a third key, a third signing group comprising one or more image frames of the third set of encoded image frames, wherein the third key pertains to the third source of input image frames.

4. The method according to claim 1 , wherein the first source of input image frames is an image sensor of a video capture device.

5. The method according to claim 4 , wherein the second source of input image frames is another sensor than the image sensor of the video capture device.

6. The method according to claim 1 , wherein the second source of input image frames is a video processing unit.

7. The method according to claim 6 , wherein the video processing unit comprises a graphical overlay adding function.

8. The method according to claim 1 , wherein the first key is a hash function key, and/or wherein the second key is a hash function key.

9. The method according to claim 1 , wherein the encoding comprises inter and/or prediction encoding the first set of input image frames and the second set of input image frames into, respectively, the first set of encoded image frames and the second set of encoded image frames.

10. The method according to claim 1 , further comprising:

associating with the combined video stream at least one of:

a signature pertaining to the signing using the first key, and

a signature pertaining to the signing using the second key.

11. The method according to claim 1 , further comprising:

decoding, at a decoder, the combined video stream;

checking a signature comprised in said combined video stream; and

associating data pertaining to a result of said checking with the decoded video stream.

12. The method according to claim 1 , further comprising:

decoding, at a decoder, the combined video stream;

determining an origin of an image frame of said combined video stream;

associating data based on the determining of the said origin with said image frame.

13. A non-transitory computer-readable storage medium having stored thereon instructions for implementing a method, when executed on a device having processing capabilities, the method for processing a video stream comprising:

receiving a first set of input image frames comprising image data originating from a first source of input image frames;

receiving a second set of input image frames comprising image data originating from a second source of input image frames, wherein the second set of input image frames includes modifications or changes relative to the first set of image frames;

encoding the first set of input image frames and the second set of input image frames into, respectively, a first set of encoded image frames and a second set of encoded image frames, forming a combined video stream, wherein an encoded image frame of the first set of encoded image frames exclusively references one or more other encoded image frames of the first set of encoded image frames, and wherein an encoded image frame of the second set of encoded image frames references both an encoded image frame of the first set of encoded image frames and another encoded image frame of the second set of encoded image frames;

designating the first set of encoded image frames as image frames not to be displayed or designating the second set of encoded image frames as image frames to be displayed;

signing, using a first key, a first signing group comprising one or more encoded image frames of the first set of encoded image frames, wherein the first key pertains to the first source of input image frames; and

signing, using a second key, a second signing group comprising one or more encoded image frames of the second set of encoded image frames, wherein the second key pertains to the second source of input image frames.

14. A video processing system comprising a processor configured to:

receive a first set of input image frames, comprising image data originating from a first source of input image frames;

receive a second set of input image frames, comprising image data originating from a second source of input image frames, wherein the second set of input image frames includes modifications or changes relative to the first set of image frames;

encode the first set of input image frames and the second set of input image frames into, respectively, a first set of encoded image frames and a second set of encoded image frames, forming a combined video stream, wherein an encoded image frame of the first set of encoded image frames exclusively references one or more image frames of the first set of encoded image frames, and wherein an encoded image frame of the second set of encoded image frames references both an encoded image frame of the first set of encoded image frames and another encoded image frame of the second set of encoded image frames;

designate the first set of encoded image frames as image frames not to be displayed or designate the second set of encoded image frames as image frames to be displayed;

sign, using a first key, a first signing group comprising one or more encoded image frames of the first set of encoded image frames, wherein the first key pertains to the first source of input image frames;

sign, using a second key, a second signing group comprising one or more encoded image frames of the second set of encoded image frames, wherein the second key pertains to the second source of input image frames.