[FFmpeg-user] Converting zoom recordings

[Carl Zwanzig]

On 5/26/2020 11:36 PM, Edward Park wrote:
> I might be wrong but it looks like the example you uploaded is from a
> session with at least two files, maybe the other named similarly but
> ending with _02 (or maybe it is incomplete and the next part wasn't
> saved). I think it is sample buffers serialized, knowing what it is a
> recording of (type and number of streams) would help to reverse
> engineer.

Zoom -does- create two files, and the second is _02 (all recordings seem to 
have two output files). I wasn't sure the _02 was needed but will upload it.

After the zoom converter has run-
-rw-r--r-- 1 cpz None   69829 May 21 18:06 audio_only.m4a
-rw-r--r-- 1 cpz None 4495380 May 21 17:34 double_click_to_convert_01.zoom
-rw-r--r-- 1 cpz None    1907 May 21 17:34 double_click_to_convert_02.zoom
-rw-r--r-- 1 cpz None     107 May 21 18:06 playback.m3u
-rw-r--r-- 1 cpz None 1606535 May 21 18:06 zoom_0.mp4
(note timestamps)

I'm not sure how many streams it would contain, my assumption is one video 
and one audio, but I don't actually know. There were three people on the 
call, all sending their camera video into the meeting.



If the recording is paused/restarted, multiple mp4 files will be created by 
the converter even though there are only two input files.

example-
-rw-r--r-- 1 cpz None   19170859 May 16 18:01 audio_only.m4a
-rw-r--r-- 1 cpz None   20034555 May 16 18:31 audio_only_1.m4a
-rw-r--r-- 1 cpz None   41777966 May 16 19:18 audio_only_2.m4a
-rw-r--r-- 1 cpz None 1704674328 May 16 17:29 double_click_to_convert_01.zoom
-rw-r--r-- 1 cpz None     623067 May 16 17:29 double_click_to_convert_02.zoom
-rw-r--r-- 1 cpz None      72966 May 16 17:28 meeting_saved_chat.txt
-rw-r--r-- 1 cpz None        293 May 16 19:18 playback.m3u
-rw-r--r-- 1 cpz None  433705692 May 16 18:01 zoom_0.mp4
-rw-r--r-- 1 cpz None  372477324 May 16 18:31 zoom_1.mp4
-rw-r--r-- 1 cpz None  588887278 May 16 19:18 zoom_2.mp4

FWIW, the result .m3u file contains (long lines manually wrapped for email)-
#EXTM3U

#EXTINF:0,2020-05-16 13.40.43 at the con - \
   discussion 82308298761 - zoom_0.mp4
zoom_0.mp4

#EXTINF:0,2020-05-16 13.40.43 at the con - \
   discussion 82308298761 - zoom_1.mp4
zoom_1.mp4

#EXTINF:0,2020-05-16 13.40.43 at the con - \
   discussion 82308298761 - zoom_2.mp4
zoom_2.mp4
[end]


I can readily create more test files. Oh, and these were created with zoom 
client "5.0.2 (24046.0510)", which is almost current.

Later,

z!