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 non-transitory computer readable medium storing instructions that, when executed by one or more processors of a mobile device, cause the mobile device to perform a method, comprising:
acquiring a plurality of images of a pinna, wherein the plurality of images are acquired at different positions to cover the pinna;
determining geometrical values of the pinna as output from a statistical model using input based on the plurality of images, the statistical model is trained on a dataset including a plurality of pinna geometries, wherein the statistical model determines the geometrical values by reducing a set of data points representative of the pinna;
determining, based on the geometrical values, a head-related transfer function (HRTF) filter; and
producing three-dimensional sound using the HRTF filter.
2. The non-transitory computer readable medium 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 acquire the plurality of images.
3. The non-transitory computer readable medium of claim 2 , wherein the mobile device is configured to instruct a user to move the mobile device such that the plurality of images are acquired at a plurality of different angles to cover the pinna.
4. The non-transitory computer readable medium of claim 1 , wherein the plurality of images is a video sequence.
5. The non-transitory computer readable medium of claim 1 , wherein the statistical model includes a pre-computed principle component analysis basis.
6. The non-transitory computer readable medium of claim 1 , wherein the geometrical values correspond to points of significance in the pinna.
7. The non-transitory computer readable medium of claim 6 , wherein the plurality of pinna geometries have the points of significance.
8. The non-transitory computer readable medium of claim 1 , wherein determining the geometrical values includes solving a minimization problem for basis functions of the statistical model.
9. A method performed by a programmed processor of a mobile device, the method comprising:
acquiring a plurality of images of a pinna, wherein the plurality of images are acquired at different positions to cover the pinna;
determining geometrical values of the pinna as output from a statistical model using input based on the plurality of images, the statistical model is trained on a dataset including a plurality of pinna geometries, wherein the statistical model determines the geometrical values by reducing a set of data points representative of the pinna;
determining, based on the geometrical values, a head-related transfer function (HRTF) filter; and
producing three-dimensional sound using the HRTF filter.
10. The method of claim 9 , wherein the mobile device is configured to instruct a user to move the mobile device around a head of the user to acquire the plurality of images.
11. The method of claim 9 , wherein the mobile device is configured to instruct a user to move the mobile device such that the plurality of images are acquired at a plurality of different angles to cover the pinna.
12. The method of claim 9 , wherein the geometrical values correspond to points of significance in the pinna.
13. The method of claim 12 , wherein the plurality of pinna geometries have the points of significance.
14. The method of claim 9 , wherein determining the geometrical values includes solving a minimization problem for basis functions of the statistical model.
15. A mobile device comprising:
at least one processor configured to execute computer programs;
at least one memory configured to store computer programs and related data; and
at least one data communication interface configured to communicate with external data communication networks;
wherein the mobile device is configured to:
acquire a plurality of images of a pinna, wherein the plurality of images are acquired at different positions to cover the pinna,
determine geometrical values of the pinna as output from a statistical model using input based on the plurality of images, the statistical model is trained on a dataset including a plurality of pinna geometries, wherein the statistical model determines the geometrical values by reducing a set of data points representative of the pinna;
determine, based on the geometrical values, a head-related transfer function (HRTF) filter; and
produce three-dimensional sound using the HRTF filter.
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 acquire the plurality of images.
17. The mobile device of claim 16 , wherein the mobile device is configured to instruct a user to move the mobile device such that the plurality of images are acquired at a plurality of different angles to cover the pinna.
18. The mobile device of claim 15 , wherein the geometrical values correspond to points of significance in the pinna.
19. The mobile device of claim 18 , wherein the plurality of pinna geometries have the points of significance.
20. The mobile device of claim 15 , wherein determining the geometrical values includes solving a minimization problem for basis functions of the statistical model.