105 lines
4.0 KiB
Markdown
105 lines
4.0 KiB
Markdown
---
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title: Time Jitter
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sidebar_label: Time Jitter
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hide_title: false
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hide_table_of_contents: false
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---
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# TimeJitter
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This article describes the timestamp correct of SRS.
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## RTMP Monotonically Increase Timestamp
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RTMP requires the timestamp is mono-inc(monotonically increase). The mono-inc is the
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timestamp of packet is always larger.
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RTMP requires the stream is mono-inc. The audio is mono-inc,
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video is mono-inc, and stream mixed audio with video is mono-inc.
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What happens when not mono-inc? Some server will disconnect connection, flash maybe
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failed to play stream.
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## Timestamp Jitter
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SRS will ensure the stream timestamp is mono-inc. When delta of packets too large, set to 40ms(fps 25).
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Some components use the timestamp jitter:
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* RTMP delivery: The timestamp jitter algorithm can set by vhost `time_jitter`.
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* DVR: The timestamp jitter algorithm can set by dvr `time_jitter`.
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* HLS: Always ensure the timestamp is mono-inc, use `full` timestamp jitter algorithm.
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* Forward: Always ensure the timestamp is mono-inc, use `full` timestamp jitter algorithm.
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* HTTP Audio Stream Fast Cache: Equals to RTMP time jitter, the vhost config. @see `fast_cache`.
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You can disable the timestamp jitter algorithm when your encoder can not ensure the
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video+autio mono-inc, some encoder can ensure video mono-inc and audio mono-inc.
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## Config
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Config the timestamp jitter in vhost for RTMP delivery:
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```bash
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vhost jitter.srs.com {
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# for play client, both RTMP and other stream clients,
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# for instance, the HTTP FLV stream clients.
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play {
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# about the stream monotonically increasing:
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# 1. video timestamp is monotonically increasing,
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# 2. audio timestamp is monotonically increasing,
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# 3. video and audio timestamp is interleaved/mixed monotonically increasing.
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# it's specified by RTMP specification, @see 3. Byte Order, Alignment, and Time Format
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# however, some encoder cannot provides this feature, please set this to off to ignore time jitter.
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# the time jitter algorithm:
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# 1. full, to ensure stream start at zero, and ensure stream monotonically increasing.
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# 2. zero, only ensure sttream start at zero, ignore timestamp jitter.
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# 3. off, disable the time jitter algorithm, like atc.
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# default: full
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time_jitter full;
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# whether use the interleaved/mixed algorithm to correct the timestamp.
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# if on, always ensure the timestamp of audio+video is interleaved/mixed monotonically increase.
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# if off, use time_jitter to correct the timestamp if required.
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# default: off
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mix_correct off;
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}
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}
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```
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While the `mix_correct` of vhost can correct the audio+video stream to mixed monotonically increase.
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Config timestamp jitter for dvr:
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```
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vhost dvr.srs.com {
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# dvr RTMP stream to file,
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# start to record to file when encoder publish,
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# reap flv according by specified dvr_plan.
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# http callbacks:
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# @see http callback on_dvr_hss_reap_flv on http_hooks section.
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dvr {
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# about the stream monotonically increasing:
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# 1. video timestamp is monotonically increasing,
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# 2. audio timestamp is monotonically increasing,
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# 3. video and audio timestamp is interleaved monotonically increasing.
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# it's specified by RTMP specification, @see 3. Byte Order, Alignment, and Time Format
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# however, some encoder cannot provides this feature, please set this to off to ignore time jitter.
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# the time jitter algorithm:
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# 1. full, to ensure stream start at zero, and ensure stream monotonically increasing.
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# 2. zero, only ensure sttream start at zero, ignore timestamp jitter.
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# 3. off, disable the time jitter algorithm, like atc.
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# default: full
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time_jitter full;
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}
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}
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```
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## ATC
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When [RTMP ATC](./rtmp-atc.md) is on,
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RTMP always disable the time_jitter.
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Winlin 2015.4
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