Media transrating over a bandwidth-limited network

• US 20060026294A1
• Filed: 07/29/2004
• Published: 02/02/2006
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Virdi, Gurpratap, Davis, Jeffrey A.
• Granted Patent: US 7,571,246 B2
• Time in Patent Office: Days
• US Class Current: 709/232
• CPC Class Codes: H04N 21/234381 by altering the temporal resolution, e.g. decreasing the frame rate by frame skipping
• CPC Class Codes: H04N 21/23611 Insertion of stuffing data into a multiplex stream, e.g. to obtain a constant bitrate synchronisation arrangements in time-division multiplex systems using bit stuffing for systems with different or fluctuating information rates H04J3/073
• CPC Class Codes: H04N 21/2402 Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
• CPC Class Codes: H04N 21/4392 involving audio buffer management
• CPC Class Codes: H04N 21/44209 Monitoring of downstream path of the transmission network originating from a server, e.g. bandwidth variations of a wireless network arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896
• CPC Class Codes: H04N 21/4424 Monitoring of the internal components or processes of the client device, e.g. CPU or memory load, processing speed, timer, counter or percentage of the hard disk space used error monitoring in general G06F11/30; arrangements for monitoring conditions of receiving stations in broadcast systems H04H60/32; diagnosis, testing or measuring for television receivers H04N17/04
• CPC Class Codes: H04N 21/658 Transmission by the client directed to the server
• CPC Class Codes: H04N 21/6582 Data stored in the client, e.g. viewing habits, hardware capabilities, credit card number arrangements where receivers interact with the broadcast H04H20/38

Abstract

A transrate manager on a host computer determines if there is a limitation in network bandwidth and controls the bit-rate of streaming media content accordingly. The bit-rate is controlled by excluding types of video frames from the streaming media content and then reintroducing excluded types of video frames back into the streaming video content once the network has recovered.

Claims

1. A method comprising:

transmitting a media stream over a network;

receiving feedback data that indicates network bandwidth availability; and

excluding video frames from the media stream during the transmitting in response to the feedback data.

2. A method as recited in claim 1, wherein the excluding video frames comprises:

estimating the network bandwidth availability based on the feedback data; and

selectively excluding particular types of video frames from the media stream based on estimated network bandwidth availability.

3. A method as recited in claim 2, wherein the feedback data comprises buffer fullness reports from a playback device, and the estimating the network bandwidth availability comprises:

determining that the network bandwidth availability is low if the buffer fullness reports indicate an audio buffer on the playback device is being depleted; and

determining that the network bandwidth availability is high if the buffer fullness reports indicate the audio buffer on the playback device is not being depleted.

4. A method as recited in claim 2, wherein the selectively excluding particular types of video frames comprises excluding delta video frames.

5. A method as recited in claim 4, wherein the selectively excluding particular types of video frames further comprises excluding key video frames.

6. A method as recited in claim 4, wherein the media stream is an mpeg media stream and the excluding delta video frames comprises excluding B (bi-directional) video frames.

7. A method as recited in claim 4, wherein the media stream is an mpeg media stream and the excluding delta video frames comprises excluding P (predictive) video frames.

8. A method as recited in claim 5, wherein the media stream is an mpeg media stream and the excluding key video frames comprises excluding every nth I (intra) video frame.

9. A method as recited in claim 1, wherein the receiving feedback data comprises receiving a buffer fullness report from a playback device.

10. A method as recited in claim 1, wherein the receiving feedback data comprises receiving buffer fullness reports at a periodic rate from a playback device.

11. A method as recited in claim 1, wherein the receiving feedback data comprises receiving buffer fullness reports at a varying rate from a playback device, the varying rate depending on the network bandwidth availability.

12. A method as recited in claim 11, wherein the receiving buffer fullness reports at a varying rate comprises:

receiving buffer fullness reports at an increased rate if the network bandwidth availability is low; and

receiving buffer fullness reports at a decreased rate if the network bandwidth availability is high.

13. A method as recited in claim 1, wherein the network bandwidth availability is limited, the method further comprising:

testing the network bandwidth availability after the excluding video frames; and

reintroducing excluded types of video frames back into the media stream if the testing reveals that the network bandwidth availability is no longer limited.

14. A method as recited in claim 13, wherein the transmitting occurs at an initial bit-rate and the excluding video frames reduces the initial bit-rate to a reduced bit-rate, and wherein the testing comprises:

introducing an increasing number of padding data packets into the media stream to increase the reduced bit-rate;

monitoring the feedback data to determine if an audio buffer on a playback device is being depleted; and

reintroducing excluded types of video frames back into the media stream if the increasing number of padding data packets increases the reduced bit-rate up to the initial bit-rate without the audio buffer being depleted.

15. A method as recited in claim 14, further comprising ceasing the introducing of the padding data packets concurrently with the reintroducing excluded types of video frames.

16. A method as recited in claim 3, wherein the determining that the network bandwidth availability is low comprises determining from the buffer fullness reports that the audio buffer is being depleted at a minimum threshold rate.

17. A processor-readable medium comprising processor-executable instructions configured for performing the method of claim 1.

18. A method comprising:

receiving streaming media content from a host device at a full frame transmission level;

transmitting a buffer fullness report to the host device; and

receiving the streaming media content from the host device at a reduced frame transmission level after transmitting the buffer fullness report.

19. A method as recited in claim 18, wherein the transmitting further comprises:

monitoring an audio buffer to determine a buffer fullness level; and

generating the buffer fullness report including the buffer fullness level.

20. A method as recited in claim 18, further comprising playing back the streaming media content received at the full frame transmission level.

21. A method as recited in claim 18, further comprising:

duplicating video frames from the streaming media content received at the reduced frame transmission level; and

playing back the duplicated video frames along with the streaming media content received at the reduced frame transmission level.

22. A processor-readable medium comprising processor-executable instructions configured for:

transmitting a media stream to a playback device over a network;

receiving buffer fullness reports from the playback device;

dropping a type of video frame from the media stream if the buffer fullness reports indicate that an audio buffer on the playback device is being depleted.

23. A processor-readable medium as recited in claim 22, wherein the dropping a type of video frame comprises changing the transmitting from a full frame transmission level to a reduced frame transmission level.

24. A processor-readable medium as recited in claim 22, wherein the full frame transmission level includes I (intra), B (bi-directional), and P (predictive) types of video frames, and the reduced frame transmission level is selected from the group comprising:

I and P video frame transmission level;

I video frame transmission level; and

nth I video frame transmission level.

25. A processor-readable medium as recited in claim 24, wherein the dropping a type of video frame from the media stream comprises:

monitoring a fullness value in the buffer fullness reports;

determining that the audio buffer on the playback device is being depleted; and

changing the transmitting from the full frame transmission level to the I and P video frame transmission level.

26. A processor-readable medium as recited in claim 25, wherein the dropping a type of video frame from the media stream further comprises:

continuing the monitoring;

determining that the audio buffer on the playback device is still being depleted; and

changing the transmitting from the I and P video frame transmission level to the I video frame transmission level.

27. A processor-readable medium as recited in claim 26, wherein the dropping a type of video frame from the media stream further comprises:

continuing the monitoring;

determining that the audio buffer on the playback device is still being depleted; and

changing the transmitting from the I video frame transmission level to the nth I video frame transmission level.

28. A processor-readable medium as recited in claim 22, comprising further processor-executable instructions configured for:

after dropping a type of video frame from the media stream, determining from the buffer fullness reports that the audio buffer is no longer being depleted;

testing the network to determine if dropped types of video frames can be reintroduced into the media stream without causing further depletion of the audio buffer; and

reintroducing dropped types of video frames back into the media stream if the reintroducing will not cause further depletion of the audio buffer.

29. A processor-readable medium as recited in claim 28, wherein the transmitting initially occurs at a first bit rate and the dropping a type of video frame causes the transmitting to occur at a reduced second bit rate, the testing comprising:

after determining that the audio buffer is no longer being depleted, transmitting increasing numbers of padding data packets along with the media stream while monitoring buffer fullness reports; and

if the padding data packets and the media stream being transmitted together raise the second bit rate back up to the first bit rate, reintroducing the dropped types of video frames back into the media stream.

30. A processor-readable medium as recited in claim 28, comprising further processor-executable instructions configured for stopping the transmitting of padding data packets simultaneous with the reintroducing the dropped types of video frames back into the media stream.

31. A computer comprising the processor-readable medium of claim 22.

32. A computer comprising:

a media buffer configured to receive streaming media content from a host device;

a player application configured to access the media buffer and playback the streaming media content; and

a buffer monitor configured to monitor a fullness level of an audio buffer and to transmit buffer fullness reports to the host device.

33. The computer as recited in claim 32, selected from the group comprising:

a desktop PC;

a notebook PC;

a handheld PC;

a personal digital assistant (PDA);

a cellular telephone;

a gaming console;

a set-top box;

a workstation; and

an Internet appliance.

34. A computer comprising:

media content;

a transrater configured to stream the media content over a network to a playback device; and

a transrate manager configured to determine if the network has a bandwidth limitation and to control the transrater to stream the media content at different rates depending on the bandwidth limitation.

35. A computer as recited in claim 34, further comprising:

buffer fullness reports received from the playback device;

wherein the transrate manager is further configured to analyze the buffer fullness reports to determine if the network has a bandwidth limitation.