From 14a49c354ee525d7e4ac0d1aa3ea22d3f02f90f7 Mon Sep 17 00:00:00 2001 From: "Steinar H. Gunderson" Date: Sun, 9 Jul 2017 01:36:07 +0200 Subject: [PATCH] Write a section on Kaeru. --- streaming.rst | 48 +++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 45 insertions(+), 3 deletions(-) diff --git a/streaming.rst b/streaming.rst index d6c4456..e8c09ef 100644 --- a/streaming.rst +++ b/streaming.rst @@ -45,7 +45,7 @@ most browsers in the \ tag:: while :; do vlc -I dummy -v --network-caching 3000 \ - http://http://yourserver.example.org:9095/stream.nut vlc://quit \ + http://yourserver.example.org:9095/stream.nut vlc://quit \ --sout '#transcode{vcodec=h264,vb=1500,acodec=mp4a,aenc=fdkaac,ab=128}:std{mux=ffmpeg{mux=mp4},access=http{mime=video/mp4},dst=:1994}' \ --sout-avformat-options '{movflags=empty_moov+frag_keyframe+default_base_moof}' \ --sout-x264-vbv-maxrate 1500 --sout-x264-vbv-bufsize 1500 \ @@ -72,6 +72,10 @@ created by VLC into a stream that will be accepted by most smartphones:: -hls_time 2 -hls_wrap 100 -bsf:v h264_mp4toannexb \ -hls_segment_filename $NAME-hls-%03d.ts stream.m3u8 +See also the section on :ref:`Kaeru `, below. + + +.. _direct-encoding: Direct encoding --------------- @@ -132,12 +136,50 @@ around with the default timebase Nageru is using. If so, please add the “--http-coarse-timebase” flag. +.. _kaeru: + +Transcoding with Kaeru +---------------------- + +There is a third option that combines elements from the two previous +approaches: Since version 1.6.1, Nageru includes **Kaeru**, named after the +Japanese verb *kaeru* (換える), meaning roughly to replace or exchange. +Kaeru is a command-line tool that is designed to transcode Nageru's streams. +In that aspect, it is similar to using VLC as described in the section on +:ref:`transcoded streaming `. However, since it reuses +Nageru's decoding and encoding code, it can do almost everything you can do +with :ref:`direct encoding `, including x264 speed control +and Metacube output (see the section on :ref:`Cubemap integration ` below). + +Using Kaeru is similar to launching Nageru, e.g. to rescale a stream to 848x480:: + + ./kaeru -w 848 -h 480 --http-mux mp4 --http-audio-codec libfdk_aac --http-audio-bitrate 128 \ + http://yourserver.example.org:9095/stream.nut + +Unlike the VLC option, Kaeru will automatically reconnect if the source goes +away, so you do not need a while loop. Note that if you want to keep the audio +unchanged (usually audio is more important than video, so it's not uncommon to +want to transcode video but not audio), you can do so with the flag +*--no-transcode-audio* flag. + +There are some things you should keep in mind about Kaeru: + + - Kaeru is currently quite experimental, and much less tested than Nageru itself. + - Kaeru does not use the GPU; it uses FFmpeg's code for scaling and colorspace + conversion. This yields somewhat lower scaling quality and uses more CPU power, + but means you can run it on a headless server. + - There is no support for encoding using Quick Sync Video, since this depends on the GPU. + - 10-bit output is currently not supported. + + +.. _cubemap: + Cubemap integration ------------------- Even with built-in x264 support, Nageru is not particularly efficient for delivering streams to end users. For this, a natural choice is -`Cubemap `_; Cubemap scales without problems +`Cubemap `__; Cubemap scales without problems to multiple 10 Gbit/sec NICs on a quite normal machine, and you can easily add multiple Cubemap servers if so needed. Nageru has native support for Cubemap's *Metacube2* transport encoding; simply add “.metacube” to @@ -148,7 +190,7 @@ to the end of the URL, e.g. with a cubemap.config fragment like this:: Note that you will want a pacing rate of about 2:1 to your real average bitrate, in order to provide some for temporary spikes (the default allows spikes of 2x the nominal bitrate, but only on a one-second basis) and -TCP retransmits. See the cubemap documentation for more information about +TCP retransmits. See the Cubemap documentation for more information about how to set up pacing. For transcoded Cubemap output from VLC you can take exactly the same line as -- 2.39.2