Instead of simply playing back the frames through `ffplay`, I thought it
might be interesting to be able to record the sequence to a video file
or to use it as part of a stream.
I have in mind the use case of making educational videos/live streams
where the tablet can be used as a kind of remote blackboard by teachers,
which is especially relevant currently. But there are certainly other
use cases!
Changes
=======
This commit adds two new options to that effect:
* `-o --output`: Path of the output as understood by `ffmpeg` (usually a
file name). If this is `-` (as it is by default), the existing behavior
of playing the stream through `ffplay` is restored.
* `-f --format`: When recording to an output, this option can be used to
force the encoding format. If this is `-` (again, the default),
`ffmpeg`’s auto format detection is used (based on the file extension).
Because of the possible confusion between the newly added `--output`
option and the existing `--destination` option for specifying the source
address, I suggest renaming the `--destination` option to `--source`
(this is implemented in this commit).
Examples
========
Record to a file
----------------
```sh
./reStream.sh -o remarkable.mp4
```
Caveat: The recorded file plays back too fast.
I am not sure how to fix this.
Create an UDP MPEG-TS stream
----------------------------
```sh
./reStream.sh -o "udp://127.0.0.1:1234" -f "mpegts"
```
This sends frames over UDP to the specified port using the MPEG-TS
format (see <https://trac.ffmpeg.org/wiki/StreamingGuide>). This stream
can then be connected, for example, to OBS for live streaming (see
<https://connect.ed-diamond.com/Linux-Pratique/LP-096/Enrichir-sa-diffusion-de-contenus-multimedias-avec-OBS>
in French).
Previously, arguments were examined by a for loop, but this loop is not
affected by the `shift` commands executed inside of it.
Because the loop always advances one argument further on each iteration,
this bug goes unnoticed with the `--portrait` option (`shift` is called
once, which matches the behavior of the loop). However, handling of the
`--destination` argument is broken because of that (`shift` is called
twice but the loop only advances one argument).
This commit replaces the `for` loop by a `while` loop which always
examines the next argument and properly takes `shift`s into account.
This is based on the following SO answer:
<https://stackoverflow.com/a/7069755/3452708>
Changed the README to reflect the command line options added with
bcf62e3. Also incorporates the SSH timeout of 1 second added by the
initial PR (#10).
Co-authored-by: Aaron David Schneider <aaron.david.schneider@gmail.com>
