How to Compress a Podcast Episode for Upload

A finished podcast episode is often far larger than the upload form expects. The master may be a WAV of several hundred megabytes, while the platform will re-encode whatever you send into its own delivery format. Compressing for upload is therefore not about squeezing out the last kilobyte; it is about producing a clean, compatible listening copy without throwing away the master.

Audio Compressor takes a file and re-encodes it to MP3, AAC, Opus, or FLAC at a bitrate you choose. Work on a copy and keep the original, because every lossy encode is one-way.

Start with a master you can return to

Edit before you encode

Most of the size and most of the listening fatigue come from the edit, not the encoder. Cut long pauses, repeated takes, and filler words. Remove sections where nothing is said. If two speakers are on separate tracks, balance their levels before mixing; an uneven mix makes the quiet speaker hard to hear and encourages listeners to turn up the volume.

Reduce background noise carefully. Heavy noise reduction can leave a watery, metallic texture that survives compression and sounds worse than the original hiss. Apply it to a short sample first. For a single voice recorded on one microphone, mono is usually enough and halves the data compared with a stereo file that contains the same signal twice.

Choose a format and a bitrate range

MP3 remains the safest delivery format because almost every podcast app and older device plays it. AAC is efficient and well supported by phones and browsers, but a few niche players are happier with MP3. Opus is excellent for speech at low bitrates, though compatibility is less universal. FLAC is useful for an archive, not usually for the upload itself.

For spoken-word stereo, 96 to 128 kbps is a common working range; a mono speech file can sound clean lower than that. Music and rich sound design need more headroom than a two-person conversation. Do not assume that a higher bitrate is always better: the platform may re-encode your file anyway, and a well-edited mono file at a moderate rate can sound better than a noisy stereo file at a high one. Test on the devices your listeners actually use.

Sample rate, channels, and the upload check

44.1 kHz is a sensible delivery rate for audio; 48 kHz is common when the episode is also going to video. Do not upsample a 44.1 kHz recording to 48 kHz hoping to improve it; the extra samples contain no new information. Downsampling a higher-rate master is fine if the destination does not need the extra bandwidth.

Before uploading, listen to the exported file on a phone speaker and on headphones. Check the loudness against the platform’s guidance, confirm the duration and file size, and make sure the file plays from the beginning without a gap. If the platform publishes a preferred format, follow it rather than guessing.

The compressor processes the file on a server: the audio is sent away, converted, and deleted afterwards. The page states what is sent, so avoid confidential interviews or recordings you have not been given permission to upload. For the format comparison behind these choices, read MP3, WAV, or AAC: Which Audio Format Should You Use?

Keep the master, edit until the episode is tight, and encode one listening copy at a moderate speech bitrate. Then open Audio Compressor, encode a short sample, and compare it before you convert the full episode.