Add configurable client-side video filter support

app/deps/ffmpeg.sh

@@ -51,15 +51,14 @@ else
         --extra-cflags="-O2 -fPIC"
         --disable-programs
         --disable-doc
-        --disable-swscale
         --disable-postproc
-        --disable-avfilter
         --disable-network
         --disable-everything
         --disable-vulkan
         --disable-vaapi
         --disable-vdpau
         --enable-swresample
+        --enable-swscale
         --enable-libdav1d
         --enable-decoder=h264
         --enable-decoder=hevc
@@ -79,6 +78,12 @@ else
         --enable-muxer=opus
         --enable-muxer=flac
         --enable-muxer=wav
+        --enable-filter=buffer
+        --enable-filter=buffersink
+        --enable-filter=format
+        --enable-filter=scale
+        --enable-filter=lenscorrection
+        --enable-filter=v360
     )
 
     if [[ "$HOST" == linux ]]

app/meson.build

@@ -32,6 +32,7 @@ src = [
     'src/recorder.c',
     'src/scrcpy.c',
     'src/screen.c',
+    'src/video_filter.c',
     'src/server.c',
     'src/version.c',
     'src/hid/hid_gamepad.c',
@@ -116,6 +117,8 @@ dependencies = [
     dependency('libavformat', version: '>= 57.33', static: static),
     dependency('libavcodec', version: '>= 57.37', static: static),
     dependency('libavutil', static: static),
+    dependency('libavfilter', static: static),
+    dependency('libswscale', static: static),
     dependency('libswresample', static: static),
     dependency('sdl2', version: '>= 2.0.5', static: static),
 ]

app/scrcpy.1

@@ -614,6 +614,12 @@ The list of possible codec options is available in the Android documentation:
 
 <https://d.android.com/reference/android/media/MediaFormat>
 
+.TP
+.BI "\-\-video\-filter " filter
+Apply an FFmpeg filter graph to the decoded video before it is displayed or forwarded to V4L2.
+
+Example: --video-filter="lenscorrection=cx=0.5:cy=0.5:k1=-0.2:k2=0"
+
 .TP
 .BI "\-\-video\-encoder " name
 Use a specific MediaCodec video encoder (depending on the codec provided by \fB\-\-video\-codec\fR).

app/src/cli.c

@@ -41,6 +41,7 @@ enum {
     OPT_NO_MIPMAPS,
     OPT_CODEC_OPTIONS,
     OPT_VIDEO_CODEC_OPTIONS,
+    OPT_VIDEO_FILTER,
     OPT_FORCE_ADB_FORWARD,
     OPT_DISABLE_SCREENSAVER,
     OPT_SHORTCUT_MOD,
@@ -1006,6 +1007,15 @@ static const struct sc_option options[] = {
                 "Android documentation: "
                 "<https://d.android.com/reference/android/media/MediaFormat>",
     },
+    {
+        .longopt_id = OPT_VIDEO_FILTER,
+        .longopt = "video-filter",
+        .argdesc = "filter",
+        .text = "Apply an FFmpeg filter graph on the decoded video before it "
+                "is rendered or forwarded to V4L2.\n"
+                "Example: --video-filter=\"lenscorrection=cx=0.5:cy=0.5:"
+                "k1=-0.2:k2=0\"",
+    },
     {
         .longopt_id = OPT_VIDEO_ENCODER,
         .longopt = "video-encoder",
@@ -2656,6 +2666,9 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
             case OPT_VIDEO_CODEC_OPTIONS:
                 opts->video_codec_options = optarg;
                 break;
+            case OPT_VIDEO_FILTER:
+                opts->video_filter = optarg;
+                break;
             case OPT_AUDIO_CODEC_OPTIONS:
                 opts->audio_codec_options = optarg;
                 break;

app/src/options.c

@@ -10,6 +10,7 @@ const struct scrcpy_options scrcpy_options_default = {
     .push_target = NULL,
     .render_driver = NULL,
     .video_codec_options = NULL,
+    .video_filter = NULL,
     .audio_codec_options = NULL,
     .video_encoder = NULL,
     .audio_encoder = NULL,

app/src/options.h

@@ -235,6 +235,7 @@ struct scrcpy_options {
     const char *push_target;
     const char *render_driver;
     const char *video_codec_options;
+    const char *video_filter;
     const char *audio_codec_options;
     const char *video_encoder;
     const char *audio_encoder;

app/src/scrcpy.c

@@ -26,6 +26,7 @@
 #include "recorder.h"
 #include "screen.h"
 #include "server.h"
+#include "video_filter.h"
 #include "uhid/gamepad_uhid.h"
 #include "uhid/keyboard_uhid.h"
 #include "uhid/mouse_uhid.h"
@@ -55,6 +56,7 @@ struct scrcpy {
     struct sc_decoder audio_decoder;
     struct sc_recorder recorder;
     struct sc_delay_buffer video_buffer;
+    struct sc_video_filter video_filter;
 #ifdef HAVE_V4L2
     struct sc_v4l2_sink v4l2_sink;
     struct sc_delay_buffer v4l2_buffer;
@@ -392,6 +394,7 @@ scrcpy(struct scrcpy_options *options) {
 #ifdef HAVE_V4L2
     bool v4l2_sink_initialized = false;
 #endif
+    bool video_filter_initialized = false;
     bool video_demuxer_started = false;
     bool audio_demuxer_started = false;
 #ifdef HAVE_USB
@@ -582,10 +585,12 @@ scrcpy(struct scrcpy_options *options) {
 #ifdef HAVE_V4L2
     needs_video_decoder |= !!options->v4l2_device;
 #endif
+    bool video_decoder_initialized = false;
     if (needs_video_decoder) {
         sc_decoder_init(&s->video_decoder, "video");
         sc_packet_source_add_sink(&s->video_demuxer.packet_source,
                                   &s->video_decoder.packet_sink);
+        video_decoder_initialized = true;
     }
     if (needs_audio_decoder) {
         sc_decoder_init(&s->audio_decoder, "audio");
@@ -786,6 +791,21 @@ scrcpy(struct scrcpy_options *options) {
     // There is a controller if and only if control is enabled
     assert(options->control == !!controller);
 
+    if (options->video_filter && !video_decoder_initialized) {
+        LOGW("Ignoring --video-filter: video playback is disabled");
+    }
+
+    struct sc_frame_source *video_source = &s->video_decoder.frame_source;
+    if (video_decoder_initialized && options->video_filter) {
+        if (!sc_video_filter_init(&s->video_filter, options->video_filter)) {
+            goto end;
+        }
+
+        video_filter_initialized = true;
+        sc_frame_source_add_sink(video_source, &s->video_filter.frame_sink);
+        video_source = &s->video_filter.frame_source;
+    }
+
     if (options->window) {
         const char *window_title =
             options->window_title ? options->window_title : info->device_name;
@@ -825,7 +845,7 @@ scrcpy(struct scrcpy_options *options) {
         screen_initialized = true;
 
         if (options->video_playback) {
-            struct sc_frame_source *src = &s->video_decoder.frame_source;
+            struct sc_frame_source *src = video_source;
             if (options->video_buffer) {
                 sc_delay_buffer_init(&s->video_buffer,
                                      options->video_buffer, true);
@@ -850,7 +870,7 @@ scrcpy(struct scrcpy_options *options) {
             goto end;
         }
 
-        struct sc_frame_source *src = &s->video_decoder.frame_source;
+        struct sc_frame_source *src = video_source;
         if (options->v4l2_buffer) {
             sc_delay_buffer_init(&s->v4l2_buffer, options->v4l2_buffer, true);
             sc_frame_source_add_sink(src, &s->v4l2_buffer.frame_sink);
@@ -1051,6 +1071,10 @@ scrcpy(struct scrcpy_options *options) {
         sc_file_pusher_destroy(&s->file_pusher);
     }
 
+    if (video_filter_initialized) {
+        sc_video_filter_destroy(&s->video_filter);
+    }
+
     if (server_started) {
         sc_server_join(&s->server);
     }