Adaptive coding and streaming of multi-directional video
In communication applications, aggregate source image data at a transmitter exceeds the data that is needed to display a rendering of a viewport at a receiver. Improved streaming techniques that include estimating a location of a viewport at a future time. According to such techniques, the viewport may represent a portion of an image from a multi-directional video to be displayed at the future time, and tile(s) of the image may be identified in which the viewport is estimated to be located. In these techniques, the image data of tile(s) in which the viewport is estimated to be located may be requested at a first service tier, and the other tile in which the viewport is not estimated to be located may be requested at a second service tier, lower than the first service tier.
1. A method for streaming video data, comprising:
retrieving content of a multi-directional video from a source device at a first level of service,
estimating, from data representing movement of a display device, a first direction of movement of a gaze location among the multi-directional video content displayed on the display device;
comparing the estimated first direction of movement of gaze location to a hint of a second direction of movement identified by the source device;
when the comparison indicates that the first direction of movement aligns with the second direction of movement, requesting content of a portion of the multi-directional video at a first location along the estimated first direction of movement at a second, higher level of service; and
when the comparison indicates that the first direction of movement is not aligned with the second direction of movement, requesting content of a portion of the multi-directional video at a second location different from the first location at a second level of service.
2. The method of claim 1 , wherein the hint of the second direction of movement of determined from a manifest file associated with the multi-directional video.
3. The method of claim 1 , wherein the hint of the second direction of movement is determined from a supplemental enhancement information (SEI) message embedded in coded video.
4. The method of claim 1 , wherein the hint of the second direction of movement is a hint of a direction of movement of image content.
5. The method of claim 4 , wherein the hint of the direction of movement of image content indicates an average dominate motion in a spatial subset region of the multi-directional video.
6. The method of claim 4 , wherein the hint of the direction of movement of image content indicates an average dominate motion over an entire frame of the multi-directional video.
7. The method of claim 1 , wherein the requesting includes requesting image data for a region corresponding to a present location of a viewport of the display device at a highest service tier.
8. A rendering system, comprising:
a buffer for storing tiles of multi-directional image data;
an image output for rendering a viewport of image contents on a display; and
a controller for:
retrieving content of a multi-directional video from a source device at a first level of service, and storing the retrieved content in the buffer;
estimating, from data representing movement of a display device, a first direction of movement of a gaze location among the multi-directional video content displayed on the display device;
comparing the estimated first direction of movement of gaze location to a hint of a second direction of movement identified by the source device;
when the comparison indicates that the first direction of movement aligns with the second direction of movement, requesting content of a portion of the multi-directional video at a first location along the estimated first direction of movement at a second, higher level of service; and
when the comparison indicates that the estimated first direction of movement is not aligned with the second direction of movement, requesting content of a portion of the multi-directional video at a second location different from the first location at a second level of service.
9. The rendering system of claim 8 , wherein the hint of the second direction of movement of determined from a manifest file associated with the multi-directional video.
10. The rendering system of claim 8 , wherein the hint of the second direction of movement is determined from a supplemental enhancement information (SEI) message embedded in coded video.
11. The rendering system of claim 8 , wherein the hint of the second direction of movement is a hint of a direction of movement of image content.
12. The rendering system of claim 11 , wherein the hint of the direction of movement of image content indicates an average dominate motion in a spatial subset region of the multi-directional video.
13. The rendering system of claim 11 , wherein the hint of the direction of movement of image content indicates an average dominate motion over an entire frame of the multi-directional video.
14. A non-transitory storage medium including instructions that, when executed by a processor, cause:
retrieving content of a multi-directional video from a source device at a first level of service,
estimating, from data representing movement of a display device, a first direction of movement of a gaze location among the multi-directional video content displayed on the display device;
comparing the estimated first direction of movement of gaze location to a hint of a second direction of movement identified by the source device;
when the comparison indicates that the first direction of movement aligns with the second direction of movement, requesting content of a portion of the multi-directional video at a first location along the estimated first direction of movement at a second, higher level of service; and
when the comparison indicates that the first direction of movement is not aligned with the second direction of movement, requesting content of a portion of the multi-directional video at a second location different from the first location at a second level of service.
15. The non-transitory storage medium of claim 14 , wherein the hint of the second direction of movement of determined from a manifest file associated with the multi-directional video.
16. The non-transitory storage medium of claim 14 , wherein the hint of the second direction of movement is determined from a supplemental enhancement information (SEI) message embedded in coded video.
17. The non-transitory storage medium of claim 14 , wherein the hint of the second direction of movement is a hint of a direction of movement of image content.
18. The non-transitory storage medium of claim 17 , wherein the hint of the direction of movement of image content indicates an average dominate motion in a spatial subset region of the multi-directional video.