If you have a collection of m4s files and an init.mp4 , you can always reconstruct a full MP4 by simple concatenation. If the init is missing, you'll need to extract codec parameters from one of the fragments or the MPD manifest.
1. What is an m4s file? An m4s file (Media Segment for MPEG-DASH) is a chunk of video or audio data used in MPEG-DASH (Dynamic Adaptive Streaming over HTTP) streaming. The "m4" stands for MP4 -based container, and "s" stands for segment . m4s files
# Option 1: Find init (often "init.mp4" or "video_init.m4s") # Option 2: Use FFmpeg to generate a dummy init from first segment (imperfect but works) ffmpeg -i seg0.m4s -c copy -f mp4 dummy_init.mp4 cat dummy_init.mp4 seg*.m4s > output.mp4 Better: Use or Bento4 to reassemble correctly: If you have a collection of m4s files and an init