Low Latency
This tutorial shows how to setup Ultra low latency streaming in AMP Web SDK.
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Presentation formats
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HLS setup
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MPEG-Dash setup
1. Live streaming presentations
Player is compatible with the following low latency presentation protocols:
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LL-HLS (Low Latency HTTP Live Streaming)
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MPEG-DASH (Dynamic Adaptive Streaming over HTTP) with Chunked Transfer Encoding
2. HLS setup
AMP provides support for low-latency HLS playback techniques, utilizing partial-based segment playback and preload hints. Additionally, AMP leverages hls library for low-latency live streams utilizing LL-HLS for MSE-based user agents.
const config = {
autoplay: true,
autoplayPolicy: "muted",
media: {
src: "https://low-latency-demo.akamaized.net/live/media0/demonab/hls/demonab.m3u8"
},
hls: {
data: {
lowLatencyMode: true
}
}
}Moreover, if desired latency can be adjusted by providing the following HLS settings:
-
liveMaxLatencyDuration: The maximum permissible delay from the live edge, expressed in seconds. -
liveSyncDuration: Defines how far back in time the playback can be relative to the live edge of the stream. This number is expressed in seconds.
hls: {
data: {
lowLatencyMode: true,
liveMaxLatencyDuration: 3,
liveSyncDuration: 2
}
}3. MPEG-DASH setup
The player enables low-latency playback through progressive fragment playback with HTTP chunked-based transfer. Additionally, AMP utilizes dash.js for low-latency live streams using MPEG-DASH.
const config = {
autoplay: true,
autoplayPolicy: "muted",
media: {
src: "https://akamaibroadcasteruseast.akamaized.net/cmaf/live/657078/akasource/out.mpd"
},
dash: {
settings: {
streaming: {
lowLatencyEnabled: true
}
}
}
}Both liveDelay and playbackRate values are adjustable to optimize performance and results.
-
liveDelay: The maximum permissible delay from the live edge, expressed in seconds. -
playbackRate: Playback speed percentage to catch up the live edge if the viewer falls behind.
dash: {
settings: {
streaming: {
lowLatencyEnabled: true,
delay: {
liveDelay: 2
},
liveCatchup: {
playbackRate: 0.5
}
}
}
}