Information on this page is subject to change!
[!WARNING]
This article is out of date, and has not been rewritten yet.
Information is not guaranteed to be accurate.
Installing
Audio requires two native libraries, libsodium and opus.
Both of these libraries must be placed in the runtime directory of your
bot. (When developing on .NET Framework, this would be bin/debug,
when developing on .NET Core, this is where you execute dotnet run
from; typically the same directory as your csproj).
For Windows Users, precompiled binaries are available for your
convienence here.
For Linux Users, you will need to compile Sodium and Opus from
source, or install them from your package manager.
Joining a Channel
Joining a channel is the first step to sending audio, and will return
an IAudioClient to send data with.
To join a channel, simply await ConnectAsync on any instance of an
@Discord.IAudioChannel.
[!code-csharpJoining a Channel]
[!WARNING]
Commands which mutate voice states, such as those where you join/leave
an audio channel, or send audio, should use RunMode.Async. RunMode.Async
is necessary to prevent a feedback loop which will deadlock clients
in their default configuration. If you know that you're running your
commands in a different task than the gateway task, RunMode.Async is
not required.
The client will sustain a connection to this channel until it is
kicked, disconnected from Discord, or told to disconnect.
It should be noted that voice connections are created on a per-guild
basis; only one audio connection may be open by the bot in a single
guild. To switch channels within a guild, invoke ConnectAsync on
another voice channel in the guild.
Transmitting Audio
With FFmpeg
FFmpeg is an open source, highly versatile AV-muxing tool. This is
the recommended method of transmitting audio.
Before you begin, you will need to have a version of FFmpeg downloaded
and placed somewhere in your PATH (or alongside the bot, in the same
location as libsodium and opus). Windows binaries are available on
FFmpeg's download page.
First, you will need to create a Process that starts FFmpeg. An
example of how to do this is included below, though it is important
that you return PCM at 48000hz.
[!NOTE]
As of the time of this writing, Discord.Audio struggles significantly
with processing audio that is already opus-encoded; you will need to
use the PCM write streams.
[!code-csharpCreating FFmpeg]
Next, to transmit audio from FFmpeg to Discord, you will need to
pull an AudioOutStream from your IAudioClient. Since we're using
PCM audio, use IAudioClient.CreatePCMStream.
The sample rate argument doesn't particularly matter, so long as it is
a valid rate (120, 240, 480, 960, 1920, or 2880). For the sake of
simplicity, I recommend using 1920.
Channels should be left at 2, unless you specified a different value
for -ac 2 when creating FFmpeg.
Finally, audio will need to be piped from FFmpeg's stdout into your
AudioOutStream. This step can be as complex as you'd like it to be, but
for the majority of cases, you can just use Stream.CopyToAsync, as
shown below.
If you are implementing a queue for sending songs, it's likely that
you will want to wait for audio to stop playing before continuing on
to the next song. You can await AudioOutStream.FlushAsync to wait for
the audio client's internal buffer to clear out.
[!code-csharpSending Audio]
