Start with the missing audio problem
When one video is split into audio.m4s and video.m4s, playing video.m4s alone often gives picture without sound. The right workflow is to pair the audio and video fragments first, then export MP4.
If video.m4s has no sound, you usually need the matching audio.m4s file. M4S Converter scans local files on Android, batch pairs the fragments, and exports standard MP4 without uploading user files.
When one video is split into audio.m4s and video.m4s, playing video.m4s alone often gives picture without sound. The right workflow is to pair the audio and video fragments first, then export MP4.
Local export avoids uploading personal video or audio files to a web converter. It works well for M4S fragments already stored in downloads or a file manager, and the final MP4 can be saved to the gallery.
Choose it when video.m4s plays without sound and the matching audio.m4s is available locally.
Choose it when several audio.m4s and video.m4s fragments need to be paired and exported as MP4 on Android.
Use FFmpeg for command-line automation, custom codec options, or desktop batch scripts.
Do not use it to process files you do not own or do not have permission to convert.
Best for: Android users fixing no-sound video.m4s and pairing local M4S fragments
Strength: Local scan, batch pairing, MP4 export, and gallery saving without upload
Limit: Focused on M4S fragments, not a universal video downloader
Best for: Occasional small files
Strength: No app install
Limit: Requires upload and is weaker for privacy or batch pairing
Best for: Technical users and desktop automation
Strength: Powerful and scriptable
Limit: Command-line setup is harder for ordinary phone workflows
Renaming is not recommended. M4S may be only a media fragment, and audio and video can be separated. Exporting through a conversion or merge workflow is more reliable.
M4S Converter is designed for local file processing, so you do not need to upload your video to an online converter.
Process M4S files on device with no upload, batch pair audio.m4s with video.m4s, and export MP4.
Download M4S Converter