Use lz4 instead of zstd, add prebuilt static library

README.md

@@ -29,19 +29,15 @@ On your **reMarkable** nothing is needed, unless you want...
 
 ### Sub-second latency
 
-To achieve sub-second latency, you'll need [zstd](https://zstd.net) on your
-host and on your reMarkable. 
+To achieve sub-second latency, you'll need [lz4](https://github.com/lz4/lz4) 
+on your host and on your reMarkable.
 
-You can install `zstd` on your host with your usual package manager. On Ubuntu,
-`apt install zstd` will work.
+You can install `lz4` on your host with your usual package manager. On Ubuntu,
+`apt install liblz4-tool` will do the trick.
 
-On your **reMarkable** you can do `opkg install zstd` if you have [entware](https://github.com/evidlo/remarkable_entware) installed. If you don't you can use the binary provided in this repository. In general you shouldn't trust binaries strangers on the internet provide to you, but I provide the option if you don't want the hassle of installing entware.
-
-You can install `zstd` on your reMarkable with the following steps:
-- Copy zstd: `scp zstd.arm root@10.11.99.1:~/zstd`
-- SSH to your reMarkable `ssh root@10.11.99.1`
-- Create the opt lib directory `mkdir -p /opt/lib`
-- Symlink a needed library `ln -s /lib/ld-linux-armhf.so.3 /opt/lib/ld-linux.so.3`
-
-This is currently a bit cumbersome. I'm trying to make this a bit easier.
+On your **reMarkable** you'll need a binary of `lz4` build for the arm platform,
+you can do this yourself by [installing the reMarkable toolchain](https://remarkablewiki.com/devel/qt_creator#toolchain)
+and compiling `lz4` from source with the toolchain enabled, or you can use the
+statically linked binary I have already built and put in this repo.
 
+Copy the `lz4` program to your reMarkable with `scp lz4.arm.static root@10.11.99.1:~/lz4` and you're ready to go.

reStream.sh

@@ -11,7 +11,7 @@ bytes_per_pixel=2
 loop_wait="true"
 loglevel="info"
 
-# check if we are able to reach the remarkabl
+# check if we are able to reach the remarkable
 if ! ssh "$ssh_host" true; then
     echo "$ssh_host unreachable"
     exit 1
@@ -25,22 +25,23 @@ fallback_to_gzip() {
     sleep 2
 }
 
-# check if zstd is present on remarkable
-if ssh "$ssh_host" "[ -f /opt/bin/zstd ]"; then
-    compress="/opt/bin/zstd"
-elif ssh "$ssh_host" "[ -f ~/zstd ]"; then
-    compress="~/zstd"
+
+# check if lz4 is present on remarkable
+if ssh "$ssh_host" "[ -f /opt/bin/lz4 ]"; then
+    compress="/opt/bin/lz4"
+elif ssh "$ssh_host" "[ -f ~/lz4 ]"; then
+    compress="~/lz4"
 fi
 
-# gracefully degrade to gzip if zstd is not present on remarkable or host
+# gracefully degrade to gzip if is not present on remarkable or host
 if [ -z "$compress" ]; then
-    echo "Your remarkable does not have zstd."
+    echo "Your remarkable does not have lz4."
     fallback_to_gzip
 elif ! which zstd; then
-    echo "Your host does not have zstd."
+    echo "Your host does not have lz4."
     fallback_to_gzip
 else
-    decompress="zstd -d"
+    decompress="lz4 -d"
 fi