mirror of
https://github.com/shaka-project/shaka-player.git
synced 2026-06-16 16:16:40 +03:00
Joey Parrish
84 lines
2.9 KiB
HTML
84 lines
2.9 KiB
HTML
<!--
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Copyright 2015 Google Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<h3 class="tutorial-heading">
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Live Streaming Issues
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</h3>
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<p>
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Shaka Player supports live streaming since v1.3.0. Live streams are handled by
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{@link shaka.player.DashVideoSource}, and there is no difference in the API for
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live vs static content.
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</p>
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<p>
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Live content can, however, contain large timestamps. This can make the built-in
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controls on the video tag (or any other naive UI) confusing. The currentTime on
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the video may report as something like 397002:54:56. This is not a very helpful
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or meaningful number to the user. Plus, if the video "started" over 300k+ hours
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ago, seeking to 0 is not realistic. The server is surely not keeping that much
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content sitting around.
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</p>
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<p>
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In reality, live content limits the range in which the user may seek. One live
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stream may allow the user to seek backward 5 minutes, while another may allow 4
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hours. If a user tries to seek to a point outside of this range, the player can
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clamp this value to one within the seek range. Better still is to show the user
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a meaningful range of content in the seek UI.
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</p>
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<h3 class="tutorial-heading">
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Seek Range Events
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</h3>
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<p>
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{@link shaka.player.DashVideoSource.event:SeekRangeChanged} events give the app
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the information it needs to present a better live stream UI. An app which does
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not support live streams may safely ignore them. An app which does not support
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seeking in a live stream may also ignore them.
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</p>
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<p>
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A SeekRangeChanged event contains "start" and "end" timestamps which define the
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range of time which is currently seekable. Over time, this window of available
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content will move to the right in the video timeline.
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</p>
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<p>
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The "end" time corresponds to the most recent available live content. Therefore
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to jump forward to the "live edge", the application would set video.currentTime
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to the range's "end" time.
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</p>
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<p>
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Rather than display actual timestamps from the video stream, which may be quite
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large, we recommend displaying an offset from the live edge. For example, when
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the user is watching content 1 minute and 30 seconds behind the live edge, show
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"-1:30".
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</p>
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<p>
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During live playback, the user's offset from the live edge is roughly constant,
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so any time code displayed would only be changed by buffering or seeking.
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</p>
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<p>
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For an example of a UI which uses the SeekRangeChanged event, see controls.js.
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</p>
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