Systems and methods for bandwidth-limited video transport
Systems and methods for bandwidth-limited video transport are configured to receive (or otherwise discern) a selection of video parameter limits that correspond to a bandwidth limit and apply the video parameter limits to an input video stream to enforce the bandwidth limit while preserving video quality. Methods may include adjusting the video stream one parameter at a time until the adjusted video stream meets the bandwidth limit. Parameters to be adjusted may include image resolution, frame rate, image compression, color depth, bits per pixel, and/or color encoding. In some embodiments, the image resolution is reduced first, the frame rate is reduced next, and the image compression is increased last. The extent and/or order of the adjustments of the parameters may be selected by the user, based on the content of the video stream, and/or based on the bandwidth limit.
1. A method performed by a video transport system, the method comprising:
receiving an input video stream at a video input port of a video input device;
configuring the video input device with a bandwidth limit, an image resolution limit, a frame rate limit, and a compression factor limit related to the input video stream, wherein a different bandwidth limit is allocated for each of a plurality of video streams; and
responsive to determining, by a bandwidth limiting module of the video input device, that a bandwidth of the input video stream exceeds the bandwidth limit;
scaling, using a video scaling module of the video input device, an image resolution of the input video stream by an image scale factor less than one to create a reduced image resolution;
producing, by the bandwidth limiting module, a first-stage bandwidth of a scaled video stream with the reduced image resolution, an input frame rate and an input compression factor of the input video stream;
responsive to determining, by the bandwidth limiting module, that (i) the first-stage bandwidth is still greater than the bandwidth limit, (ii) the input frame rate is greater than the frame rate limit, and (iii) the input compression factor is less than the compression factor limit, transforming the input frame rate by a frame rate transformation factor less than one to create a second-stage bandwidth of an adjusted video stream with the reduced image resolution, the transformed frame rate and the input compression factor;
responsive to determining, by the bandwidth limiting module, that the second-stage bandwidth is still greater than the bandwidth limit and the input compression factor is less than the compression factor limit, applying a compression factor to the adjusted video stream by multiplying the input compression factor by the compression factor, wherein the compression factor is less than the compression factor limit to create a modified video stream; and
responsive to the modified video stream being compatible with the bandwidth limit, outputting, by an output port, the modified video stream.
2. The method of claim 1 , wherein receiving the input video stream includes receiving a compressed video stream with the input compression factor greater than unity and decompressing the compressed video stream to form the input video stream with the input compression factor being unity.
3. The method of claim 1 , wherein the image resolution limit includes an image width limit and an image height limit, wherein the image resolution includes an image width and an image height, and wherein determining the reduced image resolution includes determining the image scale factor by calculating a minimum value of a ratio of the image width limit to the image width and a ratio of the image height limit to the image height.
4. The method of claim 1 , wherein the image resolution limit includes a pixel number limit and the image resolution includes a pixel number, and wherein the determining the reduced image resolution includes determining the image scale factor by calculating a square root of a ratio of the pixel number limit to the pixel number.
5. The method of claim 1 , wherein the input frame rate includes determining the frame rate transformation factor by calculating a ratio of the bandwidth limit to the bandwidth.
6. The method of claim 1 , wherein the input video stream has a bits-per-pixel, wherein the image resolution includes a pixel number.
7. The method of claim 6 , wherein the input frame rate includes determining the frame rate transformation factor by calculating a ratio of the bandwidth limit to a product of the pixel number, the input frame rate, and the bits-per-pixel.
8. A method performed by a video transport system, the method comprising:
receiving an input video stream at a video input port of a video input device;
configuring the video input device with a bandwidth limit, an image resolution limit, a frame rate limit, and a compression factor limit related to the input video stream, wherein a different bandwidth limit is allocated for each of a plurality of video streams; and
responsive to determining, by a bandwidth limiting module of the video input device, that a bandwidth of the input video stream exceeds the bandwidth limit;
scaling, using a video scaling module of the video input device, an image resolution of the input video stream by an image scale factor less than one to create a reduced image resolution;
producing, by the bandwidth limiting module, a first-stage bandwidth of a scaled video stream with the reduced image resolution, an input frame rate and an input compression factor of the input video stream;
responsive to determining, by the bandwidth limiting module, that (i) the first-stage bandwidth is still greater than the bandwidth limit, (ii) the input frame rate is greater than the frame rate limit, and (iii) the input compression factor is less than the compression factor limit, transforming the input frame rate by the input frame rate to create a second-stage bandwidth of an adjusted video stream with the reduced image resolution, and the input compression factor; and
responsive to determining, by the bandwidth limiting module, that the second-stage bandwidth is still greater than the bandwidth limit and the input compression factor is less than the compression factor limit, applying the input compression factor to the adjusted video stream by multiplying the input video stream by the input compression factor to create a modified video stream; and
responsive to the modified video stream being compatible with the bandwidth limit, outputting, by an output port, the modified video stream.
9. The method of claim 8 , wherein the input video stream is an uncompressed video stream with the input compression factor being unity.
10. The method of claim 8 , wherein receiving the input video stream includes receiving a compressed video stream with the input compression factor greater than unity and decompressing the compressed video stream to form the input video stream with the input compression factor being unity.
11. The method of claim 8 , wherein the image resolution limit includes an image width limit and an image height limit, wherein the image resolution includes an image width and an image height, and wherein determining the reduced image resolution includes determining the image scale factor by calculating a minimum value of a ratio of the image width limit to the image width and a ratio of the image height limit to the image height.
12. The method of claim 8 , wherein the image resolution limit includes a pixel number limit and the image resolution includes a pixel number, and wherein determining the reduced image resolution includes determining the image scale factor by calculating a square root of a ratio of the pixel number limit to the pixel number.
13. The method of claim 8 , wherein the input frame rate includes determining a frame rate transformation factor by calculating a ratio of the bandwidth limit to the bandwidth.
14. The method of claim 8 , wherein the input video stream has a bits-per-pixel, wherein the image resolution includes a pixel number.
15. The method of claim 14 , wherein the input frame rate includes determining a frame rate transformation factor by calculating a ratio of the bandwidth limit to a product of the pixel number, the input frame rate, and the bits-per-pixel.
16. The method of claim 8 , further comprising:
scaling the input video stream according to the image scale factor to form the scaled video stream.
17. The method of claim 16 , wherein the scaling of the input video stream further includes transforming the scaled video stream to the input frame rate to form a transformed video stream with the image resolution.
18. The method of claim 17 , wherein the scaling the input video stream further includes compressing the transformed video stream to the input compression factor to form the transformed video stream with the image resolution, the input frame rate, and the input compression factor.
19. The method of claim 8 , wherein a video output port is configured to output the input video stream to the bandwidth limit.
20. The method of claim 8 , wherein a configuration module is configured to receive the image resolution limit, the frame rate limit, and the compression factor limit for the input video stream.