What is MP3?
MP3 (MPEG Audio Layer III) is the universal audio format for podcast distribution. It uses perceptual coding to compress audio by removing frequencies that human ears don't easily perceive, achieving significant file size reduction while maintaining acceptable quality.
Why MP3 Dominates Podcasting
| Factor | MP3 Advantage |
|---|---|
| Compatibility | Works on 100% of podcast apps and devices |
| File size | ~1MB per minute at 128kbps |
| Metadata | Supports embedded ID3 tags |
| Streaming | Efficient for progressive download |
| Industry standard | Universal enclosure support |
MP3 Encoding Settings
Bitrate Options
| Bitrate | Best For | File Size (1 hour) |
|---|---|---|
| 64 kbps | Mono speech, minimal music | ~29 MB |
| 96 kbps | Mono speech with some music | ~43 MB |
| 128 kbps | Stereo speech, standard quality | ~58 MB |
| 192 kbps | Music-heavy podcasts | ~86 MB |
| 256 kbps | High-quality music podcasts | ~115 MB |
Encoding Modes
- CBR (Constant Bitrate): Same bitrate throughout—predictable file sizes
- VBR (Variable Bitrate): Bitrate varies with content complexity—smaller files, same quality
- ABR (Average Bitrate): Targets average bitrate—balance of both
Technical Specifications
Format: MPEG Audio Layer III
Common sample rates: 44.1 kHz, 48 kHz
Channel modes: Mono, Stereo, Joint Stereo
Typical podcast bitrate: 96-128 kbps
MIME type: audio/mpeg
File extension: .mp3
MP3 vs Other Formats
| Format | Pros | Cons for Podcasting |
|---|---|---|
| MP3 | Universal support | Slightly less efficient than newer codecs |
| AAC/M4A | Better quality per bit | Limited app support |
| Opus | Excellent compression | Very limited podcast app support |
| FLAC | Lossless quality | Files too large, poor support |
Why It Matters
MP3's universal compatibility makes it the only safe choice for podcast distribution. While newer formats offer technical advantages, they risk excluding listeners on certain apps or devices.
Why MP3 compatibility is non-negotiable:
-
Every app works: From Apple Podcasts to obscure Android apps, MP3 support is universal.
-
No playback failures: Zero risk of "unsupported format" errors for any listener.
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Consistent experience: Audio sounds the same across all platforms and devices.
-
Metadata support: ID3 tags provide embedded episode information.
Quality vs. file size tradeoffs:
| Podcast Type | Recommended | Rationale |
|---|---|---|
| Solo speech | 64-96 kbps mono | Voice doesn't need high bitrate |
| Interview | 96-128 kbps mono | Multiple voices benefit from clarity |
| Music-heavy | 192 kbps stereo | Music suffers at lower bitrates |
| Audio drama | 128-192 kbps stereo | Immersive audio needs quality |
Bandwidth considerations: Higher bitrates mean larger files, which consume more listener bandwidth and cost more to deliver. For most speech podcasts, 96-128 kbps strikes the right balance—listeners can't tell the difference from higher bitrates, but files are significantly smaller.
How to Use This in Dispatch
Upload your audio in any common format and we'll convert it to an optimized MP3:
Supported upload formats:
- WAV, AIFF (lossless)
- MP3, M4A, AAC (lossy)
- FLAC, ALAC (lossless compressed)
Automatic optimization:
- Encoded to MP3 at optimal bitrate for your content type
- ID3 tags embedded with episode metadata and artwork
- LUFS loudness normalization applied
- Original file preserved if you need to re-process
Encoding settings: Configure your preferred bitrate and mono/stereo settings in Show Settings → Audio. Higher bitrates are available for music-focused podcasts.