The repaired video plays, but the sound is gone. Before trying another repair, find out whether the result contains an audio track, whether the player is using it, and what the original recording can still tell you.
Start with the result you already have
Keep the damaged original, the healthy reference if you used one, and the repaired file as separate files. Make a copy of the result for the checks below. If the original is still on a camera card, avoid writing new recordings to that card; copy the files to separate storage first.
Play a different, known-good clip on the same device to check the speakers, output device and mute controls. Then try the repaired copy in another player. If sound appears there, investigate the original player or its audio settings before treating the file as silent everywhere.
Also check the player's audio-track selector. A recording can contain more than one audio track while a player plays only one at a time. In VLC, the Audio → Audio Track menu lets you select an available track or re-enable a disabled one. Menu names can vary by player and version.
Ask the file which audio streams it exposes
If you have FFmpeg installed, its companion ffprobe can inspect the repaired copy without changing it. Run:
ffprobe -v error -select_streams a -show_entries stream=index,codec_name,sample_rate,channels,channel_layout,duration -of json "repaired-copy.mp4"Each entry in the streams array is an audio stream that ffprobe could identify in this file. An empty array means it found no readable audio stream in the result. If ffprobe instead reports that the file itself cannot be opened, treat that as an inspection failure, not as proof that no audio was ever recorded.
When an entry is present, note its codec, channels and duration. These describe what the container reports; they do not establish that the track contains the whole conversation, music or microphone recording. Compare the number of entries and their durations with what you expected, then listen to each track.
In one public untrunc issue, a user reported that a two-track recording produced one unusable output track, alternating between the original recordings. That report concerns a different tool and does not establish the cause or how often this happens.
A track exists, but you still hear nothing
First select each available audio track in the player. A separate microphone track may not be the default track, and a track can be present yet silent or damaged. OBS documents how sources can be assigned to different recording tracks; compare those assignments with the tracks you intended to save.
If you are comfortable with the command line, make a separate WAV copy of the first audio stream for listening:
ffmpeg -n -i "repaired-copy.mp4" -map 0:a:0 -vn -c:a pcm_s16le "audio-check-1.wav"This decodes one stream into a new WAV file; it does not modify the input. -n refuses to overwrite an existing output, and 0:a:0 means the first audio stream in the input, not necessarily stream index zero in ffprobe's output. For a second audio stream, use 0:a:1 and a different output name. The FFmpeg stream-selection documentation explains explicit mapping.
WAV audio can take much more disk space than compressed audio, so check available space. If FFmpeg reports decoding errors or cannot create the file, keep the message; a file that is created can still contain silence, gaps or distorted sound. Listen to its beginning, middle and end rather than assuming the conversion repaired it. The commands here were checked on short synthetic files with two audio tracks and with no audio; a damaged recording can behave differently.
No audio stream appears in the repaired file
An empty result tells you about the repaired copy, not the entire history of the original. If the damaged source is readable, inspect a copy of it with the same ffprobe command and compare the reported audio streams. If a track is visible in the source but absent from the result, note that difference alongside both stream listings before deciding whether to try another repair.
If the source fails with moov atom not found, the probe may be unable to describe its tracks. That failure alone cannot establish whether audio data survived inside it. The missing moov atom guide explains why the unreadable index and the remaining media are different questions.
Look for a separate sound recording or a complete copy made before the interruption. A healthy clip from the same setup can help a reference-based repair interpret recording parameters, but it does not contain the missing event's sound. Our guide to choosing a matching reference covers how to compare its video and audio settings.
For OBS, check the recording's saved settings and source routing from that session if they are available. A later OBS profile or a different camera clip may offer a clue, not proof of what the interrupted file recorded. If a microphone was disabled or never captured, rebuilding container information cannot invent its original audio.
Decide what the result is worth keeping
A repaired file with picture but missing expected sound can still contain useful footage. Note which tracks play and where sound stops; that record can help if you try another route. A readable audio stream or a successful WAV export is not proof that the original audio is complete or synchronized.
If you are considering an attempt with MendVid's MP4 and MOV repair workflow, the US$9.99 per-video fee is for an attempt, with applicable taxes shown at checkout. Payment must be confirmed before upload; repair and any preview follow the upload. The fee is not refunded when an attempt is unsuccessful, incomplete or cancelled after it starts; rights that cannot be waived and the payment processor's applicable rules still apply. A required reference stays on the same paid job without another payment. Read the price and repair terms before deciding.
MendVid checks outputs against the track information it can establish and may flag missing expected audio as partial recovery. If the original track layout cannot be established, you still need to compare the result with what you expected. Check the full recording, not only the preview, and keep any separate audio in its original form until you know it is usable.