Advice on the FFmpeg AAC encoder.

[nageru-docs] / streaming.rst

diff --git a/streaming.rst b/streaming.rst
index 3f6e754903bdd88b4719b42dbfc493b2664f1776..054c6595a6c7b7068f201fb357c8da04e607205d 100644 (file)
--- a/streaming.rst
+++ b/streaming.rst
@@ -18,7 +18,7 @@ Transcoded streaming
 Transcoded streaming was the only option supported before 1.3.0,
 and in many ways the conceptually simplest from Nageru's point of
 view. In this mode, Nageru outputs its “digital intermediate”
-H.264 stream (see `:ref:digital-intermediate`), and you are
+H.264 stream (see :ref:`digital-intermediate`), and you are
 responsible for transcoding it into a format that is suitable
 for streaming to clients. Thus, you can run Nageru on a regular
 laptop and then use e.g. a short-term virtual machine in the cloud
@@ -46,9 +46,9 @@ most browsers in the \<video\> tag::
       http://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 --sout-mux-caching 3000 \
-      --sout-x264-keyint 50 --sout-mux-caching 3000 \
-      --sout-x264-tune film --sout-x264-preset slow
+      --sout-x264-vbv-maxrate 1500 --sout-x264-vbv-bufsize 1500 \
+      --sout-x264-keyint 50 --sout-x264-tune film --sout-x264-preset slow \
+      --sout-mux-caching 3000
     sleep 1
   done
 
@@ -104,11 +104,14 @@ flag; e.g.::
     --http-mux mp4 --http-audio-codec libfdk_aac --http-audio-bitrate 128
 
 Note the use here of the MP4 mux and AAC audio. “libfdk_aac” signals
-te use of Franhofer's `FDK-AAC <https://github.com/mstorsjo/fdk-aac>`_ encoder
+the use of Franhofer's `FDK-AAC <https://github.com/mstorsjo/fdk-aac>`_ encoder
 from Android; it yields significantly better sound quality than e.g. FAAC,
 and it is open source, but under a somewhat cumbersome license. For this
 reason, most distributions do not compile FFmpeg with the FDK-AAC codec,
 so you will need to compile FFmpeg yourself, or use a worse codec.
+FFmpeg `recommends <https://trac.ffmpeg.org/wiki/Encode/HighQualityAudio>`_
+their own native AAC encoder (simply called “aac”) in the absence of any
+external libraries.
 
 For speed control, you can use::
 
@@ -117,7 +120,9 @@ For speed control, you can use::
 
 There are many more parameters, in particular “--x264-bitrate” to control
 the nominal bitrate (4500 kbit/sec per default, plus audio). Most of them
-are usually fine at the default, though.
+are usually fine at the default, though. Note that you can change the
+x264 bitrate on-the-fly from the video menu; this is primarily useful
+if your network conditions change abruptly.
 
 A particular note about the MP4 mux: If you plan to stream for long periods
 continuously (more than about 12–24 hours), the 32-bit timestamps may wrap