To packetize the H.264 raw stream, av_parser_parse2() (called by
av_read_frame()) knows that it has received a full frame only after it
has received some data for the next frame. As a consequence, the client
always waited until the next frame before sending the current frame to
the decoder!
On the device side, we know packets boundaries. To reduce latency,
make the device always transmit the "frame meta" to packetize the stream
manually (it was already implemented to send PTS, but only enabled on
recording).
On the client side, replace av_read_frame() by manual packetizing and
parsing.
<https://stackoverflow.com/questions/50682518/replacing-av-read-frame-to-reduce-delay>
<https://trac.ffmpeg.org/ticket/3354>
In portable builds, scrcpy-server.jar was supposed to be present in the
current directory, so in practice it worked only if scrcpy was launched
from its own directory.
Instead, find the absolute path of the executable and build a suitable
path to use scrcpy-server.jar from the same directory.
To create a portable build (with scrcpy-server.jar accessible from the
scrcpy directory), replace OVERRIDE_SERVER_PATH by a simple compilation
flag: PORTABLE.
This paves the way to use more complex rules to determine the path of
scrcpy-server.jar in portable builds.
The socket used the device-to-computer direction to stream the video and
the computer-to-device direction to send control events.
Some features, like copy-paste from device to computer, require to send
non-video data from the device to the computer.
To make them possible, use two sockets:
- one for streaming the video from the device to the client;
- one for control/events in both directions.
Limit source code to 80 chars, and declare functions return type and
modifiers on a separate line.
This allows to avoid very long lines, and all function names are
aligned.
(We do this on VLC, and I like it.)
To clean up the device, the client executed "adb shell rm" once the
server was guaranteed to be started (after the connection succeeded).
This implied to track whether the installation state, and failed if an
additional tunnel was used in "forward" mode:
<https://github.com/Genymobile/scrcpy/issues/386#issuecomment-453936034>
Instead, make the server unlink itself on start.
The client passes parameters to the server via "adb shell" arguments.
Use "-" instead of "" when no crop is specified to avoid empty
arguments, which are not handled the same way on all devices.
Fixed <https://github.com/Genymobile/scrcpy/issues/337>.
Request SDL not to replace the SIGINT and SIGTERM handlers, so that the
process is immediately terminated on Ctrl+C.
This avoids process hanging on Ctrl+C during network calls on
initialization.
Some of them accepted a timeout, but it was not used since
commit 9b056f5091 anymore.
"adb reverse" currently does not work over tcpip (i.e. on a device
connected by "adb connect"):
<https://issuetracker.google.com/issues/37066218>
To work around the problem, if the call to "adb reverse" fails, then
fallback to "adb forward", and reverse the client/server roles.
Keep the "adb reverse" mode as the default because it does not involve
connection retries: when using "adb forward", the client must try to
connect successively until the server listens.
Due to the tunnel, every connect() will succeed, so the client must
attempt to read() to detect a connection failure. For this purpose, when
using the "adb forward" mode, the server initially writes a dummy byte,
read by the client.
Fixes <https://github.com/Genymobile/scrcpy/issues/5>.
The serial is needed for many server actions, but this is an
implementation detail, so the caller should not have to provide it on
every call.
Instead, store the serial in the server instance on server_start().
This paves the way to implement the "adb forward" fallback properly.
On user request to quit, two kinds of blocking calls must be interrupted
on the server:
1. the reads from and writes to the socket;
2. the call to MediaCodec.dequeueOutputBuffer().
The former case was handled by calling shutdown() on the socket from the
client, but the latter was not managed.
There is no easy way to wake this call properly, so just terminate the
process from the client (i.e. send SIGTERM on Linux) instead.
The server is copied to /data/local/tmp/scrcpy-server.jar and executed
on the device.
As soon as we are connected, we can unlink (rm) it from /data/local/tmp,
to keep the device clean.
The server is currently a JAR, but it may ba an APK or a DEX, so the
variable name should not contain the type.
Rename the environment variable, the Meson options and the C
definitions.
SDL_net is not very suitable for scrcpy.
For example, SDLNet_TCP_Accept() is non-blocking, so we have to wrap it
by calling many SDL_Net-specific functions to make it blocking.
But above all, SDLNet_TCP_Open() is a server socket only when no IP is
provided; otherwise, it's a client socket. Therefore, it is not possible
to create a server socket bound to localhost, so it accepts connections
from anywhere.
This is a problem for scrcpy, because on start, the application listens
for nearly 1 second until it accepts the first connection, supposedly
from the device. If someone on the local network manages to connect to
the server socket first, then they can stream arbitrary H.264 video.
This may be troublesome, for example during a public presentation ;-)
Provide our own simplified API (net.h) instead, implemented for the
different platforms.
The client was built with Meson, the server with Gradle, and were run by
a Makefile.
Add a Meson script for the server (which delegates to Gradle), and a
parent script to build and install both the client and the server to the
system, typically with:
meson --buildtype release build
cd build
ninja
sudo ninja install
In addition, use a separate Makefile to build a "portable" version of
the application (where the client expects the server to be in the
current directory). Typically:
make release-portable
cd dist/scrcpy
./scrcpy
This is especially useful for Windows builds, which are not "installed".
SDLNet_TCP_Close() not only closes, but also release the resources.
Therefore, we must not close the socket if another thread attempts to
read it.
For that purpose, move socket closing from server_stop() to
server_destroy().
Do not wait 100ms anymore to let the server print any exception: we
justly want to ignore them.
Moreover, there is no nanosleep() on Windows, so this solve another
problem.
The server is built as an APK to simplify the build, but in fact this is
a simple jar (it is not even signed).
In order to avoid confusion, rename it to .jar, so that users do not try
to "adb install" it.
Also rename it from "scrcpy" to "scrcpy-server" to distinguish from the
client-side.
The server path may be customized using SCRCPY_APK. If its basename is
different from "scrcpy.apk", it will be pushed with a different name,
so the execution would fail.
Therefore, force the push target filename.
Accept a parameter to limit the video size.
For instance, with "-m 960", the great side of the video will be scaled
down to 960 (if necessary), while the other side will be scaled down so
that the aspect ratio is preserved. Both dimensions must be a multiple
of 8, so black bands might be added, and the mouse positions must be
computed accordingly.
