Your choice of codec and bitrate determines how your radio sounds to listeners and how much bandwidth it uses. This article covers the main options and how they apply to CloudRadio.
Codecs overview
A codec compresses raw audio into a smaller format for streaming. The three codecs used in internet radio are MP3, AAC, and Opus.
MP3
MP3 is the most widely supported audio codec. Nearly every device, player, and radio directory accepts MP3 streams.
- Universal compatibility with hardware and software players
- Supported by Shoutcast, Icecast, and HLS
- At equivalent bitrates, MP3 sounds slightly worse than AAC or Opus
- Best choice when maximum device compatibility matters
- CloudRadio One includes a legacy ICY endpoint at 128 kbps MP3 alongside HLS, specifically for compatibility with older hardware and directories
AAC
AAC (Advanced Audio Coding) delivers better audio quality than MP3 at the same bitrate. At 128 kbps, AAC sounds comparable to MP3 at 160-192 kbps.
- Better quality-per-bitrate than MP3
- Native support on iOS, macOS, Android, and modern browsers
- Used by CloudRadio One for all HLS renditions
- Some older hardware players and internet radio directories do not support AAC
Opus
Opus is a newer codec designed for both speech and music. It offers the best quality-per-bitrate of the three, especially at lower bitrates.
- Excellent at low bitrates (32-64 kbps)
- Good for talk-heavy stations where bandwidth matters
- Supported by Icecast and most modern browsers
- Limited support in hardware players and radio directories
Bitrate comparison
Bitrate measures how much data is used per second of audio. Higher bitrates generally mean better sound quality but use more bandwidth.
| Bitrate | MP3 quality | AAC quality | Best for |
|---|---|---|---|
| 32 kbps | Poor | Acceptable (speech) | Ultra-low bandwidth, speech only |
| 64 kbps | Acceptable (speech) | Good (speech), acceptable (music) | Talk radio, mobile listeners |
| 96 kbps | Acceptable (music) | Good (music) | Mixed content on limited bandwidth |
| 128 kbps | Good (music) | Very good (music) | Standard quality for most stations |
| 192 kbps | Very good | Near-transparent | Music-focused stations |
| 256 kbps | Near-transparent | Transparent | High-fidelity music stations |
| 320 kbps | Transparent | Transparent | Studio reference, archival |
“Transparent” means most listeners cannot distinguish the compressed audio from the uncompressed source.
Recommended settings by content type
| Content | Recommended codec | Recommended bitrate | Channels |
|---|---|---|---|
| Talk radio | AAC or MP3 | 64 kbps | Mono |
| Mixed (talk + music) | AAC or MP3 | 128 kbps | Stereo |
| Music station | AAC | 128-192 kbps | Stereo |
| High-fidelity music | AAC | 256 kbps | Stereo |
For talk-only content, mono at a lower bitrate sounds better than stereo at the same bitrate. Mono sends one channel instead of two, so the codec can use all available bits on a single, cleaner signal.
How CloudRadio handles bitrates
Media library
When you upload tracks to your media library, CloudRadio stores them at the highest practical quality. Lossless formats (WAV, FLAC, AIFF) are transcoded to MP3 at a bitrate matched to the source quality, up to 320 kbps. MP3 and OGG files are stored without re-encoding to avoid generation loss. M4A files with AAC audio are kept in their original codec.
When transcoding lossless formats, CloudRadio selects a bitrate based on the source file’s characteristics. It uses standard CBR tiers (96, 128, 160, 192, 256, or 320 kbps) and never upscales beyond what the source quality justifies. Re-encoding a 128 kbps file at 192 kbps doesn’t recover lost detail. It just inflates the file size while adding a second generation of compression artifacts.
HLS streaming (CloudRadio One)
CloudRadio One streams HLS in AAC at three quality levels:
| Rendition | Bitrate | Codec |
|---|---|---|
| HLS Hi-Fi | 256 kbps | AAC |
| HLS Standard | 128 kbps | AAC |
| HLS Mobile | 64 kbps | AAC |
Custom plans extend this to five renditions by adding 32 kbps and 16 kbps tiers.
The listener’s player selects the best rendition automatically based on network conditions. See What Is HLS Streaming? for details.
Shoutcast/Icecast outputs
For hosted radios and custom outputs, you choose the codec (MP3 or AAC) and bitrate when configuring each mount point or stream output. Valid bitrates range from 32 to 320 kbps.
Listener bandwidth usage
Higher bitrates use more of your listener’s data:
| Bitrate | Data per hour |
|---|---|
| 64 kbps | ~29 MB |
| 128 kbps | ~58 MB |
| 192 kbps | ~86 MB |
| 256 kbps | ~115 MB |
| 320 kbps | ~144 MB |
CloudRadio One includes unlimited listener bandwidth on HLS. You don’t pay extra for high-bitrate renditions or large audiences. For hosted radios, bandwidth is included in your plan based on your listener slot count.
Related
- What Is HLS Streaming? for adaptive bitrate details
- Audio Processing for how CloudRadio normalizes your tracks
- Stream Settings for configuring your encoder output