Concatenate m4s vimeo files

Question

when downloading a vimeo video my downloaded always stopped at 99%. I was left with two collections of m4s files; one for video and one for audio stream.

I tried all possible solutions an none worked for me. Renaming the extension to mp4 did not work, concatination with ffmpeg also did not work. I realised that video stream is created by an init.mp4 file followed by other segments one by one. The video player gets the information about the stream quality in a separate file, usually in text format. It then use the init.m4s file with video headers as a started and glues the segments to it in a proper order one by one. The same procedure applies to audio stream as well.

I found this solution using developer tools of the browser, hexeditor and ffmpeg:

• open the page with a video and open developer tools (CTRL-SHIFT-C in firefox)
• press play in video player and monitor network traffic in developer tools.
• a found a json file with information and save it to disk

The file had all the information about streams. There were descriptions for five video streams and three audio streams. Stream for a video 1280x720 looked like this:

    {
      "id": "b522db58",
      "base_url": "video/",
      "format": "dash",
      "mime_type": "video/mp4",
      "codecs": "avc1.640020",
      "bitrate": 2895000,
      "avg_bitrate": 1068000,
      "duration": 6787.88,
      "framerate": 25,
      "width": 1280,
      "height": 720,
      "max_segment_duration": 7,
      "init_segment": "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",
      "index_segment": "b522db58.mp4?r=dXMtd2VzdDE%3D&range=831-14434",
      "segments": [
        {
          "start": 0,
          "end": 6.08,
          "url": "b522db58.mp4?r=dXMtd2VzdDE%3D&range=14435-328375",
          "size": 313940
        },
        {

• create a file video_start.mp4 with a value of init_segmet and decode64 it with https://www.base64decode.org/ . This is our init.m4s starter.
• use hex editor and concatenade video_start.mp4 with all other .m4s files in the right order. (Tools -> File tools -> concatenate). Save as video.mp4

You can identify the right segments by looking a their size

• repeat the same procedure for audio stream:

"audio": [
    {
      "id": "d27f1f72",
      "base_url": "audio/",
      "format": "dash",
      "mime_type": "audio/mp4",
      "codecs": "mp4a.40.2",
      "bitrate": 191000,
      "avg_bitrate": 191000,
      "duration": 6787.84,
      "channels": 2,
      "sample_rate": 48000,
      "max_segment_duration": 8,
      "init_segment": "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",
      "index_segment": "d27f1f72.mp4?r=dXM%3D&range=710-14325",
      "segments": [
        {
          "start": 0,
          "end": 5.994666666666666,
          "url": "d27f1f72.mp4?r=dXM%3D&range=14326-157787",
          "size": 143461
        },

• create a file audio_start.mp4 with a value of init_segmet and decode64 it with https://www.base64decode.org/ .

• Concatenade audio_start.mp4 with all other .m4s files in the right order. (Tools -> File tools -> concatenate). Save as audio.mp4

• use ffmpeg and join both streams

ffmpeg -i video.mp4 -i audio.mp4 -c copy output.mp4

• done