Media playback apparatus and method including delay prevention system
A media playback apparatus and a method including a system for preventing a playback delay are provided. The media playback apparatus may include a delay detecting module to detect a playback delay. The playback delay detection may determine a delay caused by a network, decoding and rendering through a single measurement. When the playback delay occurs, it may be possible to eliminate the playback delay by requesting that a server provide media data having a changed profile. Since the playback delay can be determined through a single measurement of a plurality of playback delay factors, it may be possible to simply and stably perform media playback in a manner suitable for a non-plug-in environment.
1. A media playback apparatus for playing back media on a web browser, comprising at least one processor to implement:
a receiving unit configured to receive, through a first frame and a second frame, media data generated in a media service apparatus using a communication protocol which supports web services, the second frame being received subsequent to the first frame;
a first media restoring unit configured to decode the media data that is received through the first frame and the second frame, by a decoder written in a script, the script being configured to be parsed by the web browser;
a renderer configured to perform rendering to display the media data decoded by the decoder;
a delay detecting unit configured to detect a playback delay of the media data by comparing a difference Td1 between a time at which the first frame arrives at the first media restoring unit and a time stamp of the first frame with a difference Tdx between a time at which the second frame arrives at the first media restoring unit and a time stamp of the second frame, and by determining whether a difference value between the difference Tdx and the difference Td1 exceeds a predetermined time; and
a profile changing unit configured to request the media service apparatus to transmit the media data having a changed profile in response to the delay detecting unit detecting the playback delay.
2. The media playback apparatus of claim 1 , wherein the playback delay includes any one or any combination of a network delay occurring during transmission of the media data from the media service apparatus to the media playback apparatus, a decoding delay occurring in a decoding process of the first media restoring unit, and a rendering delay occurring in a rendering process of the renderer.
3. The media playback apparatus of claim 1 , wherein the delay detecting unit is further configured to detect the playback delay based on a difference value between the difference Td1 and the difference Tdx.
4. The media playback apparatus of claim 1 , wherein the receiving unit is further configured to receive a third frame according to the changed profile, in subsequent to the second frame, in response to the playback delay being detected.
5. The media playback apparatus of claim 1 , wherein the profile changing unit is further configured to transmit the changed profile in which a resolution of the media data is changed, in response to the difference value between the difference Tdx and the difference Td1 exceeding the predetermined time.
6. The media playback apparatus of claim 1 , wherein the profile changing unit is further configured to transmit the changed profile in which a bit rate of the media data is changed, in response to the difference value between the difference Tdx and the difference Td1 exceeding the predetermined time.
7. The media playback apparatus of claim 1 , wherein the profile changing unit is further configured to transmit the changed profile in which a frame rate of the media data is changed, in response to the difference value between the difference Tdx and the difference Td1 exceeding the predetermined time.
8. The media playback apparatus of claim 1 , further comprising a second media restoring unit configured to decode the received media data by another decoder embedded in the web browser.
9. The media playback apparatus of claim 8 , wherein the decoder written in the script is written in JavaScript, and the decoder embedded in the web browser is a video tag module supported by HTML5.
10. The media playback apparatus of claim 1 , wherein a receiving process in the receiving unit, a decoding process in the first media restoring unit and a rendering process in the renderer are processed in parallel by a plurality of multi-threaded web workers.
11. The media playback apparatus of claim 1 , wherein the changed profile has a lower level than a level of a current profile among a plurality of levels of profiles.
12. The media playback apparatus of claim 11 , wherein in response to the delay detecting unit detecting the playback delay of the media data after the changed profile is requested,
the profile changing unit requests the media service apparatus to transmit the media data having a profile that has a lower level than a level of the changed profile.
13. The media playback apparatus of claim 1 , wherein in response to the playback delay of the media data, which is detected after the changed profile is requested, being less than or equal to a predetermined reference value and lasting for a predetermined reference time or longer,
the profile changing unit requests the media service apparatus to transmit the media data with a profile that has a higher level than a level of the changed profile.