For each of your Caster profiles, you will have the option to configure the codec, bitrate and sample rate of the audio stream Caster sends to the Ingest Server. You also have the option to configure a reconnect setting, which dictates the default stream status Caster will use when it is powered on. This article outlines the settings you should go for depending on your broadcasting application.
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Codec setting
For your stream Codec, you have the option of MP3 or OPUS. MP3, in this case, is referring to LAME encoding.
Opus is designed to offer lower latency than LAME while also providing higher quality and more efficient compression. The reason that Opus can achieve this combination of benefits is due to its unique encoding algorithm, which allows for more complex encoding while also reducing latency.
In comparison, LAME may be more forgiving of slow internet speeds, as it is a more traditional codec that is not optimized for low-latency encoding or real-time streaming. However, even with LAME, you may experience issues if your internet connection is too slow or unstable.
Overall, the choice between Opus and LAME for live audio encoding will depend on a number of factors, including the quality of your internet connection, the requirements of your audio stream, and the compatibility of your audio players or devices. It's important to test both codecs under your specific conditions to determine which one provides the best results for your use case.
Bitrate setting
For either codec, you have the option of configuring your stream to send at 64, 128, 256 and 320 kilobytes per second.
Ultimately the bitrate you send out of Caster will be determined based on your internet connection speed.
If you plan on playing music on your stream, we recommend using a bitrate of 128k or higher if you can. For speech-based content, 64 kbps will be sufficient and may be a sensible choice for remote event broadcasting, where internet connections may be sub-optimal (live sports commentary, for example).
Sample rate
The two sample rate options are 44100Hz and 48000Hz. This should be informed by the sample rates used by your soundcard and the setting of the content in your playout system (if applicable). Matching sample rates will reduce the chance of audio artefacts creeping into your stream.
Downstream agents such as DAB transmission sites tend to use 48000Hz as a standard so if you are using the stream for this purpose, this should be a consideration.
Reconnect setting
Reconnect settings determine the startup behaviour of the Caster, as it pertains to auto-connecting the live stream.
Recover Last State
Recover Last State is the most versatile solution recommended for broadcasters. It will simply boot the Caster with the same stream status (ON or OFF) as it was set at the time it was last powered down.
Stream ON
Stream ON means that no matter what the stream state was when the Caster was last powered off, it will automatically be set to start the stream on startup. This reconnect setting is recommended for radio stations that use Caster as their primary encoder.
It is also useful if you have technically inexperienced members of the team using the device to stream, as the profile can be configured by a tech lead, handed to the user and they will connect to the right destination simply by powering on the unit (no interface use required).
Stream OFF
Stream OFF means that no matter what the stream state was when the Caster was last powered off, it will not automatically start the stream on startup.
This setting is recommended for event broadcasters utilising Premium feeds. You may have prerecorded content playing out on your stream as part of your backup live feed. Connection to the stream from an encoder would take precedence, so you would want precise control of when the encoder goes live.
For that application, having your profile configured to "Stream OFF" will ensure the encoder does not connect automatically. This allows you to set up with the piece of mind that your sound checks are not going out on air. When it's time for the event to start, head to the interface and start your stream.