What is the difference between mono and stereo audio? Mono audio has one channel; stereo has two, usually left and right. Mono plays one signal from every speaker, while stereo spreads sound across both sides. A single voice recording usually needs only one channel.
Transcribe a recording
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Files up to 2 GB · export to TXT, MD, DOCX, PDF, SRT and VTT · speaker labels and timestamps · about 30 languages
Key facts
- A stereo file holds twice the samples of a mono file at the same sample rate, so it takes about twice the space before compression.
- Mixing stereo down to mono merges left and right into one track; if the two sides carry opposite phase, parts of the sound can cancel out.
- Some interview and phone recordings put each speaker on a separate channel, which is useful for editing but does not change what a mono mix contains.
- Many phone and meeting recordings are mono already, so converting them to stereo adds size and nothing else.
- If one channel is silent or holds only hiss, a mono copy of the good channel is the better source.
What it looks like
// how many channels does the file have?
ffprobe -hide_banner meeting.wav
// Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo
// make a mono copy
ffmpeg -i meeting.wav -ac 1 meeting_mono.wav
// keep only the left channel when the right one is empty
ffmpeg -i meeting.wav -af "pan=mono|c0=c0" meeting_left.wav
More
See the full list of languages, the tools and the glossary.
Frequently asked questions
Is stereo better than mono for transcription?
Not for a single voice. Stereo spreads sound across two channels, which helps music, but speech recognition reads one clean signal and works well from mono.
Will converting to mono shrink my file?
Yes, by about half before compression, since one channel is stored instead of two. It is a simple way to bring a large recording under the size limit.
What if the voice is only on one channel?
Use that channel for the mono copy instead of mixing both. Mixing in an empty or noisy channel can lower the level of the voice.
Do I need to convert before sending to the Potok bot?
No. Send the recording as it is, up to 2 GB. Conversion is only a convenience when a file is too large or has one dead channel.
How do I see how many channels a file has?
Open the file properties in a media player or run ffprobe. The audio stream line says mono or stereo, along with the sample rate.
Sources
Each source was opened by hand on the date shown. Pages change, so open the source if a detail matters to you.
- Monaural (Wikipedia), Wikipedia · checked
- Audio codec (Wikipedia), Wikipedia · checked
Try it on your own recording
Send your voice message, audio or video to @potok_now_bot on Telegram and the text comes back in the chat.
Open @potok_now_bot in Telegram