Arrangement for producing head related transfer function filters
When three-dimensional audio is produced by using headphones, particular HRTF-filters are used to modify sound for the left and right channels of the headphone. As the morphology of every ear is different, it is beneficial to have HRTF-filters particularly designed for the user of headphones. Such filters may be produced by deriving ear geometry from a plurality of images taken with an ordinary camera, detecting necessary features from images and fitting said features to a model that has been produced from accurately scanned ears comprising representative values for different sizes and shapes. Taken images are sent to a server ( 52 ) that performs the necessary computations and submits the data further or produces the requested filter.
1. A method performed by a programmed processor of a mobile device, the method comprising:
capturing, using a camera of the mobile device, at least one image of a pinna;
determining at least one geometrical value of the pinna as output from a statistical model using input based on the at least one image, the statistical model is trained on a dataset including a plurality of pinna geometries produced from scanned ears of different sizes and shapes, wherein the statistical model determines the at least one geometrical value by reducing a set of data points representative of the pinna;
determining, based on the at least one geometrical value, a head-related transfer function (HRTF) filter; and
producing, using the HRTF filter, three-dimensional sound on the mobile device or transmitting the HRTF filter to an electronic device for production of the three-dimensional sound at the electronic device.
2. The method of claim 1 , wherein the mobile device is configured to instruct a user to move the mobile device around a head of the user to capture the at least one image.
3. The method of claim 1 , wherein the at least one image comprises a plurality of images captured using the camera, wherein the mobile device is configured to instruct a user to move the mobile device such that the plurality of images are captured at a plurality of different angles to cover the pinna.
4. The method of claim 1 , wherein the at least one geometrical value corresponds to at least one point of significance in the pinna.
5. The method of claim 4 , wherein the statistical model is trained on a dataset that have the at least one point of significance.
6. The method of claim 1 , wherein determining the at least one geometrical value comprises solving a minimization problem for basis functions of the statistical model.
7. The method of claim 1 , wherein the statistical model includes a pre-computed principle component analysis basis.
8. A non-transitory machine-readable medium storing instructions that, when executed by one or more processors of a mobile device, cause the mobile device to:
capture, using a camera of the mobile device, at least one image of a pinna;
determine at least one geometrical value of the pinna as output from a statistical model using input based on the at least one image, the statistical model is trained on a dataset including a plurality of pinna geometries produced from scanned ears of different sizes and shapes, wherein the statistical model determines the at least one geometrical value by reducing a set of data points representative of the pinna;
determine, based on the at least one geometrical value, a head-related transfer function (HRTF) filter; and
produce, using the HRTF filter, three-dimensional sound on the mobile device or transmit the HRTF filter to an electronic device for production of the three-dimensional sound at the electronic device.
9. The non-transitory machine-readable medium of claim 8 , wherein the mobile device is configured to instruct a user to move the mobile device around a head of the user to capture the at least one image.
10. The non-transitory machine-readable medium of claim 8 , wherein the at least one image comprises a plurality of images captured using the camera, wherein the mobile device is configured to instruct a user to move the mobile device such that the plurality of images are captured at a plurality of different angles to cover the pinna.
11. The non-transitory machine-readable medium of claim 8 , wherein the at least one geometrical value corresponds to at least one point of significance in the pinna.
12. The non-transitory machine-readable medium of claim 11 , wherein the statistical model is trained on a dataset that have the at least one point of significance.
13. The non-transitory machine-readable medium of claim 8 , wherein the instructions to determine the at least one geometrical value comprises instructions to solve a minimization problem for basis functions of the statistical model.
14. The non-transitory machine-readable medium of claim 8 , wherein the statistical model includes a pre-computed principle component analysis basis.
15. A mobile device comprising:
a camera;
a processor; and
memory having stored therein instructions which when executed by the processor causes the mobile device to:
capture, using the camera, at least one image of a pinna;
determine at least one geometrical value of the pinna as output from a statistical model using input based on the at least one image, the statistical model is trained on a dataset including a plurality of pinna geometries produced from scanned ears of different sizes and shapes, wherein the statistical model determines the at least one geometrical value by reducing a set of data points representative of the pinna;
determine, based on the at least one geometrical value, a head-related transfer function (HRTF) filter; and
produce, using the HRTF filter, three-dimensional sound on the mobile device or transmit the HRTF filter to an electronic device for production of the three-dimensional sound at the electronic device.
16. The mobile device of claim 15 , wherein the mobile device is configured to instruct a user to move the mobile device around a head of the user to capture the at least one image.
17. The mobile device of claim 15 , wherein the at least one image comprises a plurality of images captured using the camera, wherein the mobile device is configured to instruct a user to move the mobile device such that the plurality of images are captured at a plurality of different angles to cover the pinna.
18. The mobile device of claim 15 , wherein the at least one geometrical value corresponds to at least one point of significance in the pinna.
19. The mobile device of claim 18 , wherein the statistical model is trained on a dataset that have the at least one point of significance.
20. The mobile device of claim 15 , wherein determining the at least one geometrical value comprises solving a minimization problem for basis functions of the statistical model.