VLC Streaming

The “poor man’s” streaming solution is vlc. When you first look into what is needed to stream a file, directory or media collection locally, you will find a lot of tutorials suggesting to use a stream generator like ices2 or darkice and connect it to a streaming server like icecast2. While this can be set up in maybe 15 minutes and can be very robust, it seems to have too much complexity. The solution here is to simply use vlc. One command on the server and one command on the client.

Scenario:

• Desktop aka the server
• Laptop A
• Laptop B

Server

Browse to a directory that contains audio or video files, or use a file. Run of the following commands in the directory or file.

# 1
vlc -vvv `pwd` --sout '#rtp{mux=ts,dst=239.255.12.42,sdp=sap,name="Stream"}'
# 2
vlc -vvv --sout '#rtp{mux=ts,dst=239.255.12.42,sdp=sap,name="Stream"}' .
# 3
export RTP="#rtp{mux=ts,dst=239.255.12.42,sdp=sap,name='Stream'}"
find -name "*.mp4" -print0|xargs -0 vlc --sout $RTP

It is also possible to stream a stream. This has the advantage that the download bandwidth is used only once and that all clients play the stream via the local network. This works in principle with m3u8 and mp3 URL types.

# 1
export URL=https://example.org/stream.m3u8
# 2
export URL=https://example.org/stream.mp3
vlc --sout '#rtp{mux=ts,dst=239.255.12.42,sdp=sap,name="Stream"}' $URL

The GUI can be used to steer the stream.

While it is possible to add a dublicate rule to vlc that would display the video or play the sound on the local machine, the disadvantage of such a solution is a delay in playback. If you use, say, the desktop in room A and the laptop in room B, you would hear an unpleasant delay. To not hear a delay, just run a vlc client on a second terminal.

vlc rtp://239.255.12.42

This also has the advantage of being a test to see if it works.

Client

For each client (Laptop A, Laptop B), run a vlc that connects to this multicast address.

vlc rtp://239.255.12.42

Resources

• https://wiki.videolan.org/Documentation:Streaming_HowTo/Command_Line_Examples/
• https://wiki.videolan.org/Documentation:Streaming_HowTo_New/
• https://wiki.videolan.org/Documentation:Streaming_HowTo/Receive_and_Save_a_Stream/
• https://wiki.videolan.org/Documentation:Streaming_HowTo/Advanced_Streaming_Using_the_Command_Line/
• https://wiki.videolan.org/Documentation:Streaming_HowTo/Streaming,_Muxers_and_Codecs/
• https://wiki.videolan.org/VLC_HowTo/Transcode_multiple_videos/

Icecast examples:

• https://blog.michael.franzl.name/2013/11/25/audio-streaming/
• https://www.linuxuprising.com/2019/09/how-to-create-your-own-internet-radio.html

Ffmpeg

Stream the Local Audio Device

Sometimes a process plays something on the local audio device. For example, a 5 hour podcast or a live stream of a rocket launch that takes a long time. If you do not want to interrupt this playback, but want to change the room, it is possible to ad hoc stream the local audio device to another computer.

Start a Local Ffmpg Server

ffmpeg -f pulse -i alsa_output.pci-0000_00_1b.0.analog-stereo.monitor \
-acodec libopus -b:a 128k -vn -f rtp rtp://239.255.12.42:5004 \
-sdp_file audio_stream.sdp

If your audio device is different use:

ffmpeg -f pulse -i $(pactl list short sources | grep 'monitor' | \
awk '{print $2}' | head -n1) -acodec libopus -b:a 128k -vn \
-f rtp rtp://239.255.12.42:5004 -sdp_file audio_stream.sdp

In another shell, copy the audio_stream.sdp’ file to the remote client.

scp audio_stream.sdp remote.machine:

Start a Client on a Different Machine

For this to work, you need the audio_stream.sdp file from the server.

ffplay -protocol_whitelist file,rtp,udp -i audio_stream.sdp

History

Version	Date	Notes
0.1.2	2023-04-18	Ad hoc ffmpeg audio streams
0.1.1	2023-03-23	Streaming of streams
0.1.0	2023-03-09	Initial release with vlc

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• Last modified (via git): April 18, 2023
• Ad hoc ffmpeg audio streams (2c42a382)
• 515 words