Method and device for quality assessment of encrypted streaming media flows

1. A computer program product comprising a non-transitory computer readable medium that stores instructions, the instructions when executed on a computer causes the computer to perform:

extracting first size information about sizes of different frames of a first segment of an encrypted first streaming media flow that has a first constant bit rate (CBR);

extracting second size information about sizes of different frames of a second segment of an encrypted second streaming media flow that has a second CBR;

wherein the first CBR equals the second CBR;

determining a relationship between qualities of the first and second streaming media flows based on the first and second size information;

wherein the extracting of the first and second size information and the determining of the relationship are executed without decrypting the first and second encrypted streaming media flows;

wherein the first segment comprises a first reference frame and multiple first non-reference frames;

wherein the second segment comprises a second reference frame and multiple second non-reference frames;

extracting first type information indicative of which frame of the first segment is the first reference frame and which frames of the first segment are the first non-reference frames;

extracting second type information indicative of which frame of the second segment is the second reference frame and which frames of the second segment are the second non-reference frames; and

wherein the determining of the relationship between qualities of the first and second encrypted streaming media flows is based on the first and second size information and on the first and second type information;

wherein the non-transitory computer readable medium stores instructions for determining that the first encrypted streaming media flow has higher quality than the second encrypted streaming media flow if at least one of the following is true:

(a) a ratio between a size of the first reference frame and a size of a largest first non-reference frame is bigger than a ratio between a size of the second reference frame and a size of a largest second non-reference frame;

(b) a difference between the size of the first reference frame and the size of the largest first non-reference frame is bigger than a difference between the size of the second reference frame and the size of the largest second non-reference frame.

2. The computer program product according to claim 1 , wherein the non-transitory computer readable medium stores instructions for determining that the first encrypted streaming media flow has higher quality than the second encrypted streaming media flow if (a) the difference between the size of the first reference frame and the size of the largest first non-reference frame is bigger than (b) the difference between the size of the second reference frame and the size of the largest second non-reference frame.

3. The computer program product according to claim 1 , wherein the non-transitory computer readable medium stores instructions for determining that the first encrypted streaming media flow has higher quality than the second encrypted streaming media flow if (a) the ratio between the size of the first reference frame and the size of the largest first non-reference frame is bigger than (b) the ratio between the size of the second reference frame and the size of the largest second non-reference frame.

4. A method for quality assessment, the method comprises:

extracting first size information about sizes of different frames of a first segment of an encrypted first streaming media flow that has a first constant bit rate (CBR);

extracting second size information about sizes of different frames of a second segment of an encrypted second streaming media flow that has a second CBR;

wherein the first CBR equals the second CBR;

determining a relationship between qualities of the first and second streaming media flows based on the first and second size information;

wherein the extracting of the first and second size information and the determining of the relationship are executed without decrypting the first and second encrypted streaming media flows;

wherein the first segment comprises a first reference frame and multiple first non-reference frames;

wherein the second segment comprises a second reference frame and multiple second non-reference frames;

extracting first type information indicative of which frame of the first segment is the first reference frame and which frames of the first segment are the first non-reference frames;

extracting second type information indicative of which frame of the second segment is the second reference frame and which frames of the second segment are the second non-reference frames; and

wherein the determining of the relationship between qualities of the first and second encrypted streaming media flows is based on the first and second size information and on the first and second type information;

wherein the method comprises determining that the first encrypted streaming media flow has higher quality than the second encrypted streaming media flow if at least one of the following is true:

(a) a ratio between a size of the first reference frame and a size of a largest first non-reference frame is bigger than a ratio between a size of the second reference frame and a size of a largest second non-reference frame; and

(b) a difference between the size of the first reference frame and the size of the largest first non-reference frame is bigger than a difference between the size of the second reference frame and the size of the largest second non-reference frame.

5. The method according to claim 4 , comprising determining that the first encrypted streaming media flow has higher quality than the second encrypted streaming media flow if (a) the difference between the size of the first reference frame and the size of the largest first non-reference frame is bigger than (b) the difference between the size of the second reference frame and the size of the largest second non-reference frame.

6. The method according to claim 4 , comprising determining that the first encrypted streaming media flow has a higher quality than the second encrypted streaming media flow if (a) the ratio between the size of the first reference frame and the size of the largest first non-reference frame is bigger than (b) the ratio between the size of the second reference frame and the size of the largest second non-reference frame.

7. A device, comprising:

an information extractor arranged to:

extract a first size information about sizes of different frames of a first segment of an encrypted first streaming media flow that has a first constant bit rate (CBR); and

extract second size information about sizes of different frames of a second segment of an encrypted second streaming media flow that has a second CBR;

wherein the first CBR equals the second CBR;

wherein the first segment comprises a first reference frame and multiple first non-reference frames;

wherein the second segment comprises a second reference frame and multiple second non-reference frames;

and

a quality assessment module, arranged to determine a relationship between qualities of the first and second streaming media flows based on the first and second size information;

wherein the information extractor is arranged to extract of the first and second size information without decrypting the first and second encrypted streaming media flows;

wherein the quality assessment module is arranged to determine the relationship between the qualities of the first and second streaming media flows without decrypting the first and second encrypted streaming media flows;

wherein the information extractor is arranged to extract first type information indicative of which frame of the first segment is the first reference frame and which frames of the first segment are the first non-reference frames and extract second type information indicative of which frame of the second segment is the second reference frame and which frames of the second segment are the second non-reference frames; and

wherein the quality assessment module is arranged to determine the relationship between qualities of the first and second encrypted streaming media flows based on the first and second size information and on the first and second type information;

wherein the quality assessment is configured to determine that the first encrypted streaming media flow has higher quality than the second encrypted streaming media flow if at least one of the following is true:

(a) a ratio between a size of the first reference frame and a size of a largest first non-reference frame is bigger than a ratio between a size of the second reference frame and a size of a largest second non-reference frame; and

(b) a difference between the size of the first reference frame and the size of the largest first non-reference frame is bigger than a difference between the size of the second reference frame and the size of the largest second non-reference frame.

8. The device according to claim 7 , wherein the quality assessment module is arranged to determine that the first encrypted streaming media flow has higher quality than the second encrypted streaming media flow if (a) the difference between the size of the first reference frame and the size of the largest first non-reference frame is bigger than (b) the difference between the size of the second reference frame and the size of the largest second non-reference frame.

9. The device according to claim 7 , wherein the quality assessment module is arranged to determine that the first encrypted streaming media flow has a higher quality than the second encrypted streaming media flow if (a) the ratio between the size of the first reference frame and the size of the largest first non-reference frame is bigger than (b) the ratio between the size of the second reference frame and the size of the largest second non-reference frame.