Dash client and receiver with buffer water-level decision-making
A client/receiver downloads data over a network path between a source and the receiver coupled by the network path and stores the media data in a presentation buffer of the receiver and from there it is consumed by a presentation element. The receiver monitors a presentation buffer fill level that represents what portion of the presentation buffer contains media data not yet consumed by a presentation element. The receiver makes requests for additional data to download. If the fill level is above a high fill threshold, the receiver does not make further requests and eventually the fill level goes down. If the fill level is below a low fill threshold, the receiver restarts the downloading and updates the fill level as media data is consumed by the presentation element. The fill level might be measured in units of memory storage capacity and/or units of presentation time.
1. A method of controlling data downloading over a network path between a source and a receiver coupled by the network path, the method comprising:
downloading media data from the source, wherein downloading occurs over a number of TCP connections determined as a function of a bandwidth-delay product, the bandwidth-delay product including a product of an estimated round-trip time (ERTT) and a receive rate, the ERTT including a difference in time between transmission of a request for the media data and receipt of a response to the request, the receive rate including an average receive rate estimated over a last integer multiple of ERTT time;
storing the media data in a presentation buffer of the receiver;
monitoring a fill level of the presentation buffer, wherein the fill level represents a portion of the presentation buffer that contains media data not yet consumed by a presentation element;
if the fill level is above a high fill threshold, stopping the downloading;
if the fill level is below a low fill threshold, restarting the downloading, wherein restarting the downloading includes resetting the ERTT and the number of TCP connections to use when the media data download is restarted, wherein resetting the number of TCP connections to use comprises adjusting the number of TCP connections to use based on the bandwidth-delay product; and
updating the fill level as media data is consumed by the presentation element.
2. The method of claim 1 , wherein the fill level is measured in units of memory storage capacity.
3. The method of claim 1 , wherein the fill level is measured in units of presentation time.
4. The method of claim 1 , wherein the high fill and low fill thresholds vary over time.
5. A receiver that downloads data over a network path between a source and the receiver, comprising:
a presentation buffer configured to store downloaded media data downloaded from the source, wherein downloading of the media data occurs over a number of TCP connections determined as a function of a bandwidth-delay product, the bandwidth-delay product including a product of an estimated round-trip time (ERTT) and a receive rate, the ERTT including a difference in time between transmission of a request for the media data and receipt of a response to the request, the receive rate including an average receive rate estimated over a last integer multiple of ERTT time;
a presentation buffer monitor configured to monitor a fill level of the presentation buffer, wherein the fill level represents a portion of the presentation buffer that contains media data not yet consumed by a presentation element; and
an interface configured to send download requests, wherein if the fill level is above a high fill threshold, stopping a downloading of media data, and if the fill level is below a low fill threshold, restarting the downloading of the media data, wherein restarting the downloading includes resetting the ERTT and the number of TCP connections to use when the media data download is restarted, wherein resetting the number of TCP connections to use comprises adjusting the number of TCP connections to use based on the bandwidth-delay product, and wherein the fill level is updated as media data is consumed by the presentation element.
6. The receiver of claim 5 , wherein the fill level is measured in units of memory storage capacity.
7. The receiver of claim 5 , wherein the fill level is measured in units of presentation time.
8. The receiver of claim 5 , wherein the high fill and low fill thresholds vary over time.
9. A non-transitory computer readable medium for execution by a processor of a receiver for controlling data downloading over a network path between a source and a receiver coupled by the network path, having thereon program code comprising:
program code for downloading media data from the source, wherein downloading occurs over a number of TCP connections determined as a function of a bandwidth-delay product, the bandwidth-delay product including a product of an estimated round-trip time (ERTT) and a receive rate, the ERTT including a difference in time between transmission of a request for the media data and receipt of a response to the request, the receive rate including an average receive rate estimated over a last integer multiple of ERTT time;
program code for storing the media data in a presentation buffer of the receiver;
program code for monitoring a fill level of the presentation buffer, wherein the fill level represents a portion of the presentation buffer that contains media data not yet consumed by a presentation element;
program code for stopping the downloading if the fill level is above a high fill threshold;
program code for restarting the downloading if the fill level is below a low fill threshold, wherein restarting the downloading includes resetting the ERTT and the number of TCP connections to use when the media data download is restarted, wherein resetting the number of TCP connections to use comprises adjusting the number of TCP connections to use based on the bandwidth-delay product; and
program code for updating the fill level as media data is consumed by the presentation element.
10. The non-transitory computer readable media of claim 9 , wherein the fill level is measured in units of memory storage capacity and/or units of presentation time.
11. The non-transitory computer readable media of claim 9 , wherein the high fill and low fill thresholds vary over time.