iPhone Video Audio Editor
Fix the audio inside your videos without touching the video. Boost dialogue, equalize music, compress uneven levels — the video track passes through bit-for-bit identical.
Free download · Enhance audio & video files · No signup required
Every iPhone user has videos with great visuals and terrible audio. A family birthday dinner where the camera captured gorgeous 4K footage but the person speaking is drowned out by restaurant clatter. A university lecture recording with crisp slides visible on screen but the professor's voice barely audible from the back of the hall. An interview clip where one person is close to the microphone and the other sounds like they are in a distant tunnel. The video is fine — it is the audio that needs work.
Most video editing apps on iPhone treat this problem poorly. iMovie lets you adjust volume and apply basic audio filters, but it re-encodes the entire video when you export — degrading visual quality even if you only changed the audio. Professional apps like LumaFusion offer more granular audio control but are complex, expensive, and still re-encode the video track on every export. Simple volume booster apps only amplify — no EQ, no compression, no limiter to prevent distortion.
Hearably takes a fundamentally different approach: video passthrough with audio-only processing. When you load a video file, Hearably uses AVAssetReader to demux the container, cleanly separating the video track from the audio track. The audio is decoded to 32-bit float PCM and routed through the full enhancement chain — 10-band parametric EQ, 3-band multiband compressor, look-ahead limiter, and volume boost up to 800%. The video track is never decoded, never touched, never re-encoded.
On export, AVAssetWriter remuxes the original video track with the newly enhanced audio track into a fresh MP4 container. The video bitstream is bit-for-bit identical to the original — same codec, same bitrate, same resolution, same color space, same HDR metadata. There is zero generation loss. The file size may differ by a few kilobytes because the audio track changed, but the video quality is mathematically identical to your source file.
This matters enormously for iPhone video. Modern iPhones shoot in HEVC (H.265) at bitrates up to 150 Mbps for 4K60 and in ProRes at even higher rates. Re-encoding this footage through any third-party app's export pipeline introduces generational loss — each encode-decode cycle degrades quality through quantization artifacts and detail smearing. For a video you might edit multiple times across different tools, avoiding unnecessary re-encodes preserves quality across your entire editing workflow. Hearably's passthrough architecture guarantees that enhancing the audio never costs you a single pixel of video quality, whether you are processing a 15-second clip or a 90-minute family event recording.
How Video Passthrough Works — AVAssetReader and AVAssetWriter
Hearably's video audio editing uses Apple's AVAssetReader and AVAssetWriter APIs to perform a remux operation rather than a full transcode. The distinction is critical: a transcode decodes and re-encodes both tracks, while a remux re-packages them into a new container without touching the compressed bitstreams.
When you load a video, AVAssetReader opens the file and exposes each track independently. The video track's compressed samples — HEVC or H.264 NAL units — are read as CMSampleBuffer objects with their original encoding fully intact. Hearably never instantiates a VTDecompressionSession on the video data; the compressed packets are passed straight through. The audio track is read with a kAudioFormatLinearPCM output setting, which instructs AVAssetReader to decode the compressed audio (typically AAC) to raw 32-bit float PCM samples for processing.
These decoded PCM samples flow through Hearably's DSP chain: high-pass filter at 20 Hz, 10-band parametric EQ with biquad filters, 3-band Linkwitz-Riley crossover splitting at 250 Hz and 4 kHz, per-band compressors with independent ratio and threshold controls, per-band gain staging, and finally the look-ahead limiter with its 5 ms circular buffer. The enhanced PCM output is fed to AVAssetWriter, which encodes it to AAC (or the user's chosen export codec) and interleaves it with the passthrough video sample buffers in a new MP4 container.
The performance advantage is dramatic. Re-encoding a 1-minute 4K HEVC video on an iPhone 15 Pro takes 20-40 seconds of heavy GPU and Neural Engine work. Hearably's passthrough approach processes the same file in 3-5 seconds because it only decodes and re-encodes the audio track — roughly 128 kbps of AAC data versus 50+ Mbps of video data. Battery impact is minimal, thermal throttling is avoided, and the export completes almost instantly for typical clip lengths.
How to get the best audio on iPhone Video Audio Editor
Fix dialogue in family videos
Load the video, enable the Vocal preset to boost speech frequencies at 1-4 kHz, and add 150-200% volume boost. The multiband compressor evens out the difference between the person speaking and background party noise. Export the result and replace the original in your Camera Roll.
Enhance lecture recordings with visible slides
Lecture videos often have the professor's voice competing with room echo and HVAC hum. Use the EQ to cut 200-400 Hz (room boominess) and boost 2-4 kHz (speech clarity). The compressor keeps the level consistent when the professor moves toward and away from the microphone throughout the recording.
Clean up interview audio with uneven levels
Interviews with two participants at different distances from the microphone create wildly uneven levels. The multiband compressor is the primary tool — it reduces the loud speaker and lifts the quiet one, creating a balanced conversation. Apply a 3:1 compression ratio on the mid band for natural-sounding dynamics.
Boost quiet outdoor video recordings
Wind noise and distant sound sources make outdoor videos frustratingly quiet. The high-pass filter removes wind rumble below 80 Hz, the parametric EQ can further cut 100-250 Hz to reduce remaining wind energy, and the volume boost brings the actual content up to a comfortable listening level.
Prepare video audio before posting to social media
Social platforms re-encode your video on upload, but they encode the audio at the level you provide. A louder, spectrally balanced audio track in your source video survives the platform's lossy compression far better than a quiet original. Always enhance audio before uploading.
Import from Camera Roll, Files, or Share Sheet
Load videos from your Photos library (Camera Roll access), from the Files app (iCloud Drive, local storage, third-party cloud providers like Dropbox), or use the Share Sheet to send a video directly from another app to Hearably.
Verify video quality is preserved after export
Because Hearably never re-encodes the video track, the exported file should be nearly the same size as the original — any difference comes only from the changed audio. If you compare frames from the original and enhanced files, they will be pixel-identical because the video bitstream was never altered.
Built for this exact use case
Video Passthrough
The video track is never decoded or re-encoded. AVAssetReader/Writer remuxes the original compressed video bitstream with the enhanced audio — zero generation loss, zero visual quality degradation, bit-identical video output.
Full Audio Enhancement Chain
10-band parametric EQ, 3-band multiband compressor, look-ahead limiter, and up to 800% volume boost. The same studio-grade DSP chain as standalone audio files — applied to the audio track inside your video.
Lightning-Fast Processing
Only the audio track is decoded and re-encoded — the video passes through as-is. A 1-minute 4K HEVC video processes in 3-5 seconds instead of the 20-40 seconds a full transcode would require.
Camera Roll Integration
Load videos directly from Photos, the Files app, or any app via the Share Sheet. Enhanced videos save back to your Camera Roll or export to any destination through the standard iOS Share Sheet.
Choose your method
Different situations call for different tools. Hearably gives you both.
Chrome Extension
Enhance audio live while you stream. The extension intercepts your tab's audio and processes it in real-time — volume boost, EQ, presets — without downloading anything.
- Streaming on iPhone Video Audio Editor, Netflix, Spotify
- Video calls on Zoom, Meet, Teams
- Any website with audio
- When you want instant, always-on enhancement
Free Online Studio
Upload an audio or video file, apply volume boost + 10-band EQ, preview in real-time, then download the enhanced WAV. Your file never leaves your browser.
- Downloaded videos or music files
- Podcast episodes you want to boost before sharing
- Voice recordings, lectures, interviews
- When you need a permanently enhanced file
Pro tip: Use a YouTube-to-MP3 tool to download the audio, then enhance it in Hearably Studio with EQ + volume boost. Perfect for offline listening, DJ sets, or sharing on social media.
Three clicks to better audio
Install
Add Hearably from the Chrome Web Store. Under 300KB, installs in seconds.
Enhance
Click the Hearably icon and tap "Enhance." Boost kicks in instantly.
Enjoy
Adjust volume, EQ, and presets. Works on any website with audio.
Frequently asked questions
Does Hearably re-encode my video when I edit the audio?
No. Hearably uses AVAssetReader to separate the video and audio tracks within the container. Only the audio is decoded, enhanced, and re-encoded. The video track passes through as a bit-identical copy of the original compressed bitstream. There is no re-encoding, no quality loss, and no resolution change.
What video formats are supported?
Hearably supports any video format that iOS can natively read — MP4, MOV, and M4V containers with H.264 or HEVC (H.265) video tracks. This covers all iPhone-recorded videos, screen recordings, and most videos from external sources. Audio tracks encoded in AAC, MP3, or linear PCM are all supported.
Can I enhance audio in a 4K ProRes video?
Yes. Since the video track is never decoded or re-encoded, the video codec and resolution have no impact on processing time or quality. ProRes, HEVC, and H.264 videos all process at the same speed because only the lightweight audio track is being worked on.
How is this different from editing audio in iMovie?
iMovie re-encodes the entire video on export — even if you only touched the audio. This introduces generation loss in the video through re-compression. Hearably's passthrough approach only processes the audio, leaving the video bit-identical. Hearably also provides a 10-band parametric EQ, multiband compressor, and look-ahead limiter — significantly more audio control than iMovie's basic volume and filter options.
Will the enhanced video keep its metadata?
Yes. Hearably preserves container metadata including creation date, GPS location data, and orientation flags. The remuxed file retains the same metadata as your original, so it sorts and displays correctly in your Camera Roll and Photos library.
Can I process multiple videos at once?
Pro users can batch-process multiple videos with identical audio enhancement settings. This is ideal for processing a series of clips from the same event — apply consistent EQ, compression, and volume boost across all of them in a single operation.
Does the video stay perfectly in sync with the enhanced audio?
Yes. AVAssetWriter maintains precise presentation timestamp alignment between the video and audio tracks during the remuxing process. There is zero sync drift — lip movements match the enhanced audio exactly as in the original file.
What happens to slow-motion or time-lapse videos?
Slow-motion and time-lapse videos process identically to standard videos. The video track — including its timing metadata for variable frame rates — passes through completely untouched. The audio track is enhanced and remuxed at its original sample rate and duration.