Method and apparatus for automatic HLS bitrate adaptation
A media player system is provided for receiving and processing a media program that uses a time interval interval t D required to decode N D frames of the media program segment. The media system receives the requested media program segment, processes the segment and determines if the throughput of the media program differs from the desired presentation throughput by a tolerance amount. Both decoding and rendering performance are determined and used to determine presentation throughput, and to determine if heavier or lighter variants of the media program should be requested for subsequent media program segments.
1. A method of selecting a next sequential one of a plurality of available variant segments in an adaptive bitrate presentation, each displaying content at a respective one of a plurality of different playback qualities, selection based on a determined playback performance of at least one previously-received segment in the adaptive bitrate presentation, the method comprising:
using a local clock to determine the interval tD that was required to decode a number N D of frames of each of the at least one previously-received segments;
comparing at least the determined time interval tD with a desired playback frame interval of the media program; and
determining if the presentation throughput of the at least one previously-received media program segment differs from the desired presentation throughput by more than a tolerance amount.
2. The method of claim 1 , wherein the desired playback frame interval is specified in the master playlist.
3. The method of claim 1 , wherein N D ≥2.
4. The method of claim 1 , wherein:
N
D
=
T
S
×
R
F
α
f
wherein T s is a temporal length of the media program segment, R F is a desired frame rate, and α f is a dimensionless lead factor between two and three.
5. The method of claim 1 , including:
measuring a second time interval t R required to render N R frames of the media program segment; and
comparing a sum of the determined first time interval tD and the determined second time interval t R with the desired playback frame interval of the media program.
6. The method of claim 5 , including:
determining a first time when the decoding of the N R frames is initiated according to a local clock;
determining a second time when the decoding of the N R frames is completed according to the local clock; and
determining the time interval t R according to a difference between the second time and the first time.
7. The method of claim 6 , wherein N R ≥2.
8. The method of claim 7 , wherein
N
R
=
T
S
×
R
F
α
f
wherein T s is a temporal length of the media program segment, R F is a desired frame rate, and α f is a dimensionless lead factor between two and three.