Create a .m4s file with ffmpeg

Question

I'm rying to create .m4s files and I'm using this command with ffmpeg: ffmpeg -i input.mov -c:v copy output.m4s

The file can't be created.

Output: Unable to find a suitable output format for tempM4S.m4s tempM4S.m4s: Invalid argument

I'm guessing the file format .m4s is not supported by ffmpeg which is strange because ffmpeg can create .m4s files when trying to create segments for MPEG-DASH. Is there a workaround this problem? WIll I have to use other tools or check ffmpeg's source code for hints?

score 0 · Answer 1 · answered Feb 22 '18 at 18:12

0

m4s files do not work by themselves as they do not contain a moov box required for playback. They require an initialization fragment as well.

answered Feb 22 '18 at 18:12

szatmary

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I have an initialization fragment, I just want to create a separate m4s file so I can replace the a segment's content by another one. – Pedro Romano Barbosa Feb 23 '18 at 08:17
Do you know any sources that I can get that specify this format(m4s)? – Pedro Romano Barbosa Feb 23 '18 at 08:29

score 0 · Answer 2 · answered Feb 02 '19 at 19:16

I am guessing you want to create m4s to include it as part of m4s series. As @szatmary mentioned, these files are not independent. So you can try this:

Merge the m4s files to one mov file.
Merge your mov file with the step 1 output file.
Split again the output file of step 2 to m4s files.

Charney Kaye · Answer 3 · 2021-10-15T09:26:34.000

Here's how I achieved this. My use case is an audio-only stream. The backend service ships MPEG-DASH files to static hosting. I upload the initializing .mp4 segment once, subsequently only uploading each new .m4s segment.

Also, the playlist .mpd is updated every segment, in order to tell a newly arriving listener where to begin playback. The listener will pick up an initializing .mp4 file for the desired bitrate, followed by the current and following .m4s segments.

My source material is a series of 10-second media segments in uncompressed .wav format.
I'll run ffmpeg once per each new media segment
I've specified a segment size of 11 seconds, to ensure that ffmpeg generates exactly 1 output .m4s segment for each source media segment.

ffmpeg \
  -i pelicans-1234.wav \
  -f hls \
  -ac 2 \
  -c:a aac \
  -b:a 128k \
  -minrate 128k \
  -maxrate 128k \
  -start_number 1234 \
  -hls_fmp4_init_filename pelicans-128k-IS.mp4 \
  -hls_segment_filename pelicans-128k-%d.m4s \
  -hls_segment_type fmp4 \
  -hls_time 11 \
  temp.m3u8

Update: So far, attempts to ship an MPEG-DASH stream using this method have failed with errors (in VLC) like `mp4: Fragment sequence discontinuity detected 1 != 2` which makes me think that I need to tell ffmpeg what the starting segment number is — Charney Kaye, Oct 15 '21 at 07:47
My quest continues in https://stackoverflow.com/questions/69625970/java-mp4parser-to-create-a-single-m4s-fragment — Charney Kaye, Oct 21 '21 at 19:42

Create a .m4s file with ffmpeg

3 Answers3