Method explained
Extract audio from a corrupt MP4 (podcast & voice recovery)
Your PC crashed mid-podcast, the MP4 is corrupt — and honestly, you don't care about the video. You need the conversation. Good news: the audio track survives corruption just as well as the video does, and recovering only-the-audio is a two-step job.
Quick answer: you can't pull audio out of a container no tool can read — so repair the container first (reference-file method), then extract the track losslessly with ffmpeg -i repaired.mp4 -vn -acodec copy audio.m4a.
Why you can't extract from the broken file directly
The audio isn't a separate file inside the MP4 — it's interleaved with video in chunks, and the missing index is the only map of which chunks are which. Audio-extractor apps fail on a corrupt MP4 for the same reason players do: nothing can locate the audio samples without the index. Rebuild the index once, and both tracks come back together.
Step 1: repair the container
- Work on a copy of the broken file.
- Try
ffmpeg -i broken.mp4 -c copy fixed.mp4— occasionally enough. - Otherwise use the reference-file method: record ~10 seconds with the same app and settings (easy for podcast/screen setups — you control the recorder) and rebuild the broken file from it.
Tip for the mixed-result case: if another tool already gave you playable video with broken audio, rerun the repair from the original broken file with a proper reference clip — rebuilt timing from a template usually fixes what one-click restores (Bandicam's included) garble.
Step 2: extract the audio losslessly
Once the repaired file plays:
ffmpeg -i repaired.mp4 -vn -acodec copy audio.m4a
-vndrops the video;-acodec copycopies the AAC track bit-for-bit — no re-encode, no quality loss.- Need WAV for editing?
ffmpeg -i repaired.mp4 -vn audio.wav(decodes to PCM). - Multiple mics recorded as separate tracks? List them with
ffprobe repaired.mp4and pick with-map 0:a:1etc.
Get the conversation back
StreamSalvage repairs the crashed recording locally — free preview so you can hear that the audio survived before paying $29. Then one FFmpeg command gives you the clean track.
Download StreamSalvage for WindowsFrequently asked questions
Can I get just the audio out of a corrupted MP4?
Yes — but not directly. A corrupt MP4's audio track is trapped behind the same missing index as the video. Repair the container first (reference-file method), then extract the audio losslessly. The audio track usually survives corruption at least as well as the video.
How do I extract the audio once the MP4 is repaired?
One FFmpeg command, no quality loss: ffmpeg -i repaired.mp4 -vn -acodec copy audio.m4a. The -acodec copy flag copies the AAC track bit-for-bit instead of re-encoding it — your podcast audio stays exactly as recorded.
My repair tool recovered video but the audio is glitched — is the voice gone?
Not necessarily. Some tools rebuild the video sample table but mis-time the audio. A reference-file repair with a clip from the same recorder rebuilds both tracks' timing from the template, which often fixes audio that another tool garbled.
Do I need to upload my podcast recording to recover the audio?
No. The whole chain — container repair and audio extraction — runs locally. StreamSalvage repairs the file on your PC with a free preview, and the FFmpeg extraction step is a single offline command.