49f20074f0
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).
119 lines
2.7 KiB
Bash
Executable File
119 lines
2.7 KiB
Bash
Executable File
#!/bin/sh
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# default values for arguments
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ssh_host="root@10.11.99.1" # remarkable connected through USB
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landscape=true # rotate 90 degrees to the right
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output_path=- # display output through ffplay
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format=- # automatic output format
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# loop through arguments and process them
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while [ $# -gt 0 ]; do
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case "$1" in
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-p|--portrait)
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landscape=false
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shift
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;;
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-s|--source)
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ssh_host="$2"
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shift
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shift
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;;
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-o|--output)
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output_path="$2"
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shift
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shift
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;;
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-f|--format)
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format="$2"
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shift
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shift
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;;
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*)
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echo "Usage: $0 [-p] [-s <source>] [-o <output>] [-f <format>]"
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exit 1
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esac
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done
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# technical parameters
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width=1408
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height=1872
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bytes_per_pixel=2
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loop_wait="true"
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loglevel="info"
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ssh_cmd="ssh -o ConnectTimeout=1 "$ssh_host""
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# check if we are able to reach the remarkable
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if ! $ssh_cmd true; then
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echo "$ssh_host unreachable"
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exit 1
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fi
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fallback_to_gzip() {
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echo "Falling back to gzip, your experience may not be optimal."
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echo "Go to https://github.com/rien/reStream/#sub-second-latency for a better experience."
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compress="gzip"
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decompress="gzip -d"
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sleep 2
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}
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# check if lz4 is present on remarkable
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if $ssh_cmd "[ -f /opt/bin/lz4 ]"; then
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compress="/opt/bin/lz4"
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elif $ssh_cmd "[ -f ~/lz4 ]"; then
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compress="~/lz4"
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fi
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# gracefully degrade to gzip if is not present on remarkable or host
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if [ -z "$compress" ]; then
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echo "Your remarkable does not have lz4."
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fallback_to_gzip
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elif ! which lz4; then
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echo "Your host does not have lz4."
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fallback_to_gzip
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else
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decompress="lz4 -d"
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fi
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output_args=()
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# calculate how much bytes the window is
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window_bytes="$(($width*$height*$bytes_per_pixel))"
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# rotate 90 degrees if landscape=true
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$landscape && output_args+=('-vf' 'transpose=1')
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# read the first $window_bytes of the framebuffer
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head_fb0="dd if=/dev/fb0 count=1 bs=$window_bytes 2>/dev/null"
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# loop that keeps on reading and compressing, to be executed remotely
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read_loop="while $head_fb0; do $loop_wait; done | $compress"
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if [ "$output_path" = - ]; then
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output_command=ffplay
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else
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output_command=ffmpeg
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if [ "$format" != - ]; then
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output_args+=('-f' "$format")
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fi
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output_args+=("$output_path")
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fi
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set -e # stop if an error occurs
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$ssh_cmd "$read_loop" \
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| $decompress \
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| "$output_command" \
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-vcodec rawvideo \
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-loglevel "$loglevel" \
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-f rawvideo \
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-pixel_format gray16le \
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-video_size "$width,$height" \
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-i - \
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"${output_args[@]}"
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