+if $watch; then
+ # watch the stream and end the stream when we stop watching.
+ sleep 2
+ ffp -d "${ffp_args[@]}" ||:
+ kill %%
+ rm -f $HOME/.iank-stream-on
+fi
+
+### begin background/development docs ###
+
+# zmq vs stdin commands:
+#
+# * zmq allows targeting a specific filter when there are duplicates.
+#
+# * if you type stdin command too slow, ffmpeg will die because it stops
+# doing normal work while it is waiting.
+#
+# * zmq returns a result to the calling process, rather than printing to
+# stdout.
+#
+# * the only simple zmq tool I found, zmqsend, requires compiling. I
+# used the latest ffmpeg 7.0.1. Build like so:
+#
+# p build-dep ffmpeg/aramo
+# ./configure --enable-libzmq # i already had libzmq3-dev installed
+# make alltools
+# cp tools/zmqsend /a/opt/bin
+#
+# * ffmpeg debug output was useful in testing zmq commands.
+#
+# * Important documentation for stdin commands is only found by typing
+# "c" into the stdin of ffmpeg and reading the output.
+#
+#
+#
+# stdin command docs, before I abandoned it for zmq:
+# mkfifo -m 0600 /tmp/iank-ffmpeg
+# # ffmpeg sits and waits until we do this. dunno why.
+# echo >/tmp/iank-ffmpeg &
+# ffmpeg ... </tmp/iank-ffmpeg |& while read -r line; do : check results; done
+# # example of working commands:
+# echo "cdrawbox -1 t 0" >/tmp/iank-ffmpeg
+# echo "cdrawbox -1 t fill" >/tmp/iank-ffmpeg
+# echo "cdrawtext -1 reinit text=''" >/tmp/iank-ffmpeg
+# echo "cvolume -1 volume=1" >/tmp/iank-ffmpeg
+
+
+# For testing: to show the number of audio channels in a resulting file
+# https://stackoverflow.com/questions/47905083/how-to-check-number-of-channels-in-my-audio-wav-file-using-ffmpeg-command
+#
+# ffprobe -i /tmp/out.wav -show_entries stream=channels -select_streams a:0 -of compact=p=0:nk=1 -v 0
+
+# for a right/left speaker test:
+# https://askubuntu.com/questions/148363/which-linux-command-can-i-use-to-test-my-speakers-for-current-talk-radio-output
+# p install alsa-utils
+# speaker-test -t wav -c 2 -l 1
+
+# There are 2 other options for audio, so I wanted to do a little
+# performance measurement of this method.
+# 1 is to combine the 2 audio sources in pulse,
+# https://unix.stackexchange.com/questions/351764/create-combined-source-in-pulseaudio .
+# 1 is to record mumble and combine in post processing.
+
+### benchmark / perf tests: these are pretty inaccurate.
+# 29 seconds cpu use. video bitrate 1500k, 8 fps, 2x keyframe interval.
+# * 64k vorbis: 69.7%
+# * 128k vorbis: 70.1% (used in subsequent tests)
+# * 1 audio input: 64.3%
+# * 0 audio inputs: 59.2%
+
+# how I did perf testing: add -to 00:00:30 to ffmpeg opts to
+# conveniently exit after measurement. Then run:
+#
+# ffmpeg "${opts[@]}" &
+# pid=$!
+# sleep 29
+# ps -p $pid -o %cpu
+# kill %%
+
+# filter for only 1 audio input:
+#-filter_complex "[0]azmq,volume=precision=fixed;[1]zmq='b=tcp\://127.0.0.1\:5557',drawbox=color=0x262626,drawtext=fontsize=90: fontcolor=beige: x=40: y=40: text=''"
+# filter with 0 audio input:
+# -filter_complex "[0]zmq='b=tcp\://127.0.0.1\:5557',drawbox=color=0x262626,drawtext=fontsize=90: fontcolor=beige: x=40: y=40: text=''"
+
+
+# When things weren't working, I did some checking on newer ffmpeg to
+# see if that helped. It never did. I compiled the latest ffmpeg release
+# tarball, 7.0.1, and tried the version in debian bullseye by schrooting
+# before running ffmpeg. Building was just configure; make, but then I
+# found some flags that were needed. gpl flags r just because I noticed them.
+# ./configure --enable-libzmq --enable-libpulse --enable-libvorbis --enable-gpl --enable-version3
+#
+
+### end background/development docs ###