Lowest possible delivery timings?/ Separate incoming stream recording
We have TRMP uplink from vidiu in 540p then transcode to 360p and 340p and pack it to HLS ABR SMIL(540,360,240)
Please help to solve some questions:
1) I know about option "Low-latency stream (ideal for chat applications)" - But is there any options to make latency even lower?
2) Can we assume that delivery time from vidiu to wowza transcoder is constant and permanent in time? 3) Have option to automatically record separate incoming stream have been implemented?
4) I have set 6s HLS chunk -- that have decreased latency by 20%, but What is the duration of the live playlist? I.e. how many segments by 6 seconds are in the playlist?
There will always be some latency between the encoder and the live video. This is the nature of streaming media. A few things can help.
A) The protocol you choose for playback can add a fair amount of latency. RTSP playback and RTMP playback have lower latency than segmented HTTP delivered content like Apple HLS, MPEG-DASH, Adobe HDS, and Microsoft Smooth Streaming. The reason for this is that the player will not play a segment until the three entire segments are finished downloading to the client to help smooth out networking issues. Content is segmented into chunks based upon the keyframe distance and time specified in Wowza Streaming Engine. Apple strongly recommends ten second segments, however that increases latency dramatically.
https://developer.apple.com/library/ios/technotes/tn2224/_index.html#//apple_ref/doc/uid/DTS40009745-CH1-MEDIASTREAMSEGMENTATION-USE_10_SECOND_TARGET_DURATIONS
B) Make sure that your keyframe distance, also known as a "Group of Pictures" or GOP, is two seconds and is consistent. Your encoder should be using the H.264 video codec and have an option to make sure that keyframes are created at that exact distance every time. If you can, please force the keyframe distance using whichever option your encoder documentation specifies.
C) We have a guide that may help provide insight in lowering your latency for RTMP playback for desktop players.
https://www.wowza.com/docs/how-to-set-up-low-latency-applications-in-wowza-streaming-engine-for-rtmp-streaming
More on low latency can be found at the following link.
https://www.wowza.com/blog/what-is-low-latency-and-who-needs-it
D) If you are delivering content using Apple HLS, Adobe HDS, Microsoft Smooth Streaming, or MPEG-DASH you will want to modify your ChunkDurationTarget as shown in the following articles:
Apple HLS:
https://www.wowza.com/docs/how-to-configure-apple-hls-packetization-cupertinostreaming
Adobe HDS:
https://www.wowza.com/docs/how-to-configure-adobe-hds-packetization-sanjosestreaming
Microsoft Smooth Streaming:
https://www.wowza.com/docs/how-to-configure-microsoft-smooth-streaming-packetization-smoothstreaming
MPEG-DASH:
https://www.wowza.com/docs/how-to-configure-mpeg-dash-packetization-mpegdashstreaming
I hope that this helps to address your latency concerns.
