scale_filter

Make the decoder independant of the SDL event mechanism.

app/meson.build

@@ -15,7 +15,6 @@ src = [
     'src/opengl.c',
     'src/receiver.c',
     'src/recorder.c',
-    'src/resizer.c',
     'src/scrcpy.c',
     'src/screen.c',
     'src/server.c',
@@ -115,6 +114,16 @@ conf.set('PORTABLE', get_option('portable'))
 conf.set('DEFAULT_LOCAL_PORT_RANGE_FIRST', '27183')
 conf.set('DEFAULT_LOCAL_PORT_RANGE_LAST', '27199')
 
+# the default max video size for both dimensions, in pixels
+# overridden by option --max-size
+conf.set('DEFAULT_MAX_SIZE', '0')  # 0: unlimited
+
+# the default video orientation
+# natural device orientation is 0 and each increment adds 90 degrees
+# counterclockwise
+# overridden by option --lock-video-orientation
+conf.set('DEFAULT_LOCK_VIDEO_ORIENTATION', '-1')  # -1: unlocked
+
 # the default video bitrate, in bits/second
 # overridden by option --bit-rate
 conf.set('DEFAULT_BIT_RATE', '8000000')  # 8Mbps

app/src/cli.c

@@ -10,9 +10,6 @@
 #include "util/log.h"
 #include "util/str_util.h"
 
-#define STR_IMPL_(x) #x
-#define STR(x) STR_IMPL_(x)
-
 void
 scrcpy_print_usage(const char *arg0) {
     fprintf(stderr,
@@ -26,7 +23,7 @@ scrcpy_print_usage(const char *arg0) {
         "    -b, --bit-rate value\n"
         "        Encode the video at the given bit-rate, expressed in bits/s.\n"
         "        Unit suffixes are supported: 'K' (x1000) and 'M' (x1000000).\n"
-        "        Default is " STR(DEFAULT_BIT_RATE) ".\n"
+        "        Default is %d.\n"
         "\n"
         "    --codec-options key[:type]=value[,...]\n"
         "        Set a list of comma-separated key:type=value options for the\n"
@@ -84,7 +81,7 @@ scrcpy_print_usage(const char *arg0) {
         "        Possible values are -1 (unlocked), 0, 1, 2 and 3.\n"
         "        Natural device orientation is 0, and each increment adds a\n"
         "        90 degrees rotation counterclockwise.\n"
-        "        Default is -1 (unlocked).\n"
+        "        Default is %d%s.\n"
         "\n"
         "    --max-fps value\n"
         "        Limit the frame rate of screen capture (officially supported\n"
@@ -94,7 +91,7 @@ scrcpy_print_usage(const char *arg0) {
         "        Limit both the width and height of the video to value. The\n"
         "        other dimension is computed so that the device aspect-ratio\n"
         "        is preserved.\n"
-        "        Default is 0 (unlimited).\n"
+        "        Default is %d%s.\n"
         "\n"
         "    -n, --no-control\n"
         "        Disable device control (mirror the device in read-only).\n"
@@ -108,8 +105,7 @@ scrcpy_print_usage(const char *arg0) {
         "\n"
         "    -p, --port port[:port]\n"
         "        Set the TCP port (range) used by the client to listen.\n"
-        "        Default is " STR(DEFAULT_LOCAL_PORT_RANGE_FIRST) ":"
-                              STR(DEFAULT_LOCAL_PORT_RANGE_LAST) ".\n"
+        "        Default is %d:%d.\n"
         "\n"
         "    --prefer-text\n"
         "        Inject alpha characters and space as text events instead of\n"
@@ -301,7 +297,12 @@ scrcpy_print_usage(const char *arg0) {
         "\n"
         "    Drag & drop APK file\n"
         "        Install APK from computer\n"
-        "\n", arg0);
+        "\n",
+        arg0,
+        DEFAULT_BIT_RATE,
+        DEFAULT_LOCK_VIDEO_ORIENTATION, DEFAULT_LOCK_VIDEO_ORIENTATION >= 0 ? "" : " (unlocked)",
+        DEFAULT_MAX_SIZE, DEFAULT_MAX_SIZE ? "" : " (unlimited)",
+        DEFAULT_LOCAL_PORT_RANGE_FIRST, DEFAULT_LOCAL_PORT_RANGE_LAST);
 }
 
 static bool

app/src/decoder.c

@@ -2,7 +2,6 @@
 
 #include <libavformat/avformat.h>
 #include <libavutil/time.h>
-#include <SDL2/SDL_events.h>
 #include <unistd.h>
 
 #include "events.h"
@@ -11,9 +10,29 @@
 #include "util/buffer_util.h"
 #include "util/log.h"
 
+// set the decoded frame as ready for rendering, and notify
+static void
+push_frame(struct decoder *decoder) {
+    bool previous_frame_skipped;
+    video_buffer_offer_decoded_frame(decoder->video_buffer,
+                                     &previous_frame_skipped);
+    if (previous_frame_skipped) {
+        // the previous callback will consume this frame
+        return;
+    }
+
+    decoder->cbs->on_new_frame(decoder, decoder->cbs_userdata);
+}
+
 void
-decoder_init(struct decoder *decoder, struct video_buffer *vb) {
+decoder_init(struct decoder *decoder, struct video_buffer *vb,
+             const struct decoder_callbacks *cbs, void *cbs_userdata) {
     decoder->video_buffer = vb;
+
+    assert(cbs);
+    assert(cbs->on_new_frame);
+    decoder->cbs = cbs;
+    decoder->cbs_userdata = cbs_userdata;
 }
 
 bool
@@ -30,20 +49,11 @@ decoder_open(struct decoder *decoder, const AVCodec *codec) {
         return false;
     }
 
-    decoder->frame = av_frame_alloc();
-    if (!decoder->frame) {
-        LOGE("Could not create decoder frame");
-        avcodec_close(decoder->codec_ctx);
-        avcodec_free_context(&decoder->codec_ctx);
-        return false;
-    }
-
     return true;
 }
 
 void
 decoder_close(struct decoder *decoder) {
-    av_frame_free(&decoder->frame);
     avcodec_close(decoder->codec_ctx);
     avcodec_free_context(&decoder->codec_ctx);
 }
@@ -58,11 +68,11 @@ decoder_push(struct decoder *decoder, const AVPacket *packet) {
         LOGE("Could not send video packet: %d", ret);
         return false;
     }
-    ret = avcodec_receive_frame(decoder->codec_ctx, decoder->frame);
+    ret = avcodec_receive_frame(decoder->codec_ctx,
+                                decoder->video_buffer->decoding_frame);
     if (!ret) {
         // a frame was received
-        video_buffer_producer_offer_frame(decoder->video_buffer,
-                                          &decoder->frame);
+        push_frame(decoder);
     } else if (ret != AVERROR(EAGAIN)) {
         LOGE("Could not receive video frame: %d", ret);
         return false;
@@ -70,7 +80,7 @@ decoder_push(struct decoder *decoder, const AVPacket *packet) {
 #else
     int got_picture;
     int len = avcodec_decode_video2(decoder->codec_ctx,
-                                    decoder->frame,
+                                    decoder->video_buffer->decoding_frame,
                                     &got_picture,
                                     packet);
     if (len < 0) {

app/src/decoder.h

@@ -10,13 +10,21 @@ struct video_buffer;
 
 struct decoder {
     struct video_buffer *video_buffer;
-
     AVCodecContext *codec_ctx;
-    AVFrame *frame;
+
+    const struct decoder_callbacks *cbs;
+    void *cbs_userdata;
+};
+
+struct decoder_callbacks {
+     // Called when a new frame can be consumed by
+     // video_buffer_take_rendering_frame(decoder->video_buffer).
+    void (*on_new_frame)(struct decoder *decoder, void *userdata);
 };
 
 void
-decoder_init(struct decoder *decoder, struct video_buffer *vb);
+decoder_init(struct decoder *decoder, struct video_buffer *vb,
+             const struct decoder_callbacks *cbs, void *cbs_userdata);
 
 bool
 decoder_open(struct decoder *decoder, const AVCodec *codec);

app/src/input_manager.c

@@ -480,7 +480,9 @@ input_manager_process_key(struct input_manager *im,
                 return;
             case SDLK_i:
                 if (!shift && !repeat && down) {
-                    switch_fps_counter_state(im->fps_counter);
+                    struct fps_counter *fps_counter =
+                        im->video_buffer->fps_counter;
+                    switch_fps_counter_state(fps_counter);
                 }
                 return;
             case SDLK_n:

app/src/input_manager.h

@@ -16,7 +16,6 @@
 struct input_manager {
     struct controller *controller;
     struct video_buffer *video_buffer;
-    struct fps_counter *fps_counter;
     struct screen *screen;
 
     // SDL reports repeated events as a boolean, but Android expects the actual

app/src/resizer.c

@@ -1,132 +0,0 @@
-#include "resizer.h"
-
-#include <assert.h>
-
-#include "util/log.h"
-
-bool
-sc_resizer_init(struct sc_resizer *resizer, struct video_buffer *vb_in,
-                struct video_buffer *vb_out, struct size size) {
-    bool ok = sc_mutex_init(&resizer->mutex);
-    if (!ok) {
-        return false;
-    }
-
-    ok = sc_cond_init(&resizer->req_cond);
-    if (!ok) {
-        sc_mutex_destroy(&resizer->mutex);
-        return false;
-    }
-
-    resizer->resized_frame = av_frame_alloc();
-    if (!resizer->resized_frame) {
-        sc_cond_destroy(&resizer->req_cond);
-        sc_mutex_destroy(&resizer->mutex);
-        return false;
-    }
-
-    resizer->vb_in = vb_in;
-    resizer->vb_out = vb_out;
-    resizer->size = size;
-
-    resizer->input_frame = NULL;
-    resizer->has_request = false;
-    resizer->has_new_frame = false;
-    resizer->interrupted = false;
-
-    return true;
-}
-
-void
-sc_resizer_destroy(struct sc_resizer *resizer) {
-    av_frame_free(&resizer->resized_frame);
-    sc_cond_destroy(&resizer->req_cond);
-    sc_mutex_destroy(&resizer->mutex);
-}
-
-static bool
-sc_resizer_swscale(struct sc_resizer *resizer) {
-    assert(!resizer->resized_frame->buf[0]); // The frame must be "empty"
-
-    return false;
-}
-
-static int
-run_resizer(void *data) {
-    struct sc_resizer *resizer = data;
-
-    sc_mutex_lock(&resizer->mutex);
-    while (!resizer->interrupted) {
-        while (!resizer->interrupted && !resizer->has_request) {
-            sc_cond_wait(&resizer->req_cond, &resizer->mutex);
-        }
-
-        if (resizer->has_new_frame) {
-            resizer->input_frame =
-                video_buffer_consumer_take_frame(resizer->vb_in);
-
-            resizer->has_new_frame = false;
-        }
-
-        resizer->has_request = false;
-        sc_mutex_unlock(&resizer->mutex);
-
-        // Do the actual work without mutex
-        sc_resizer_swscale(resizer);
-
-        video_buffer_producer_offer_frame(resizer->vb_out,
-                                          &resizer->resized_frame);
-
-        sc_mutex_lock(&resizer->mutex);
-    }
-    sc_mutex_unlock(&resizer->mutex);
-
-    return 0;
-}
-
-bool
-sc_resizer_start(struct sc_resizer *resizer) {
-    LOGD("Starting resizer thread");
-
-    bool ok = sc_thread_create(&resizer->thread, run_resizer, "resizer",
-                               resizer);
-    if (!ok) {
-        LOGE("Could not start resizer thread");
-        return false;
-    }
-
-    return true;
-}
-
-void
-sc_resizer_stop(struct sc_resizer *resizer) {
-    sc_mutex_lock(&resizer->mutex);
-    resizer->interrupted = true;
-    sc_cond_signal(&resizer->req_cond);
-    sc_mutex_unlock(&resizer->mutex);
-
-    video_buffer_interrupt(resizer->vb_out);
-}
-
-void
-sc_resizer_join(struct sc_resizer *resizer) {
-    sc_thread_join(&resizer->thread, NULL);
-}
-
-void
-sc_resizer_process_new_frame(struct sc_resizer *resizer) {
-    sc_mutex_lock(&resizer->mutex);
-    resizer->has_request = true;
-    resizer->has_new_frame = true;
-    sc_cond_signal(&resizer->req_cond);
-    sc_mutex_unlock(&resizer->mutex);
-}
-
-void
-sc_resizer_process_new_size(struct sc_resizer *resizer, struct size size) {
-    sc_mutex_lock(&resizer->mutex);
-    resizer->size = size;
-    resizer->has_request = true;
-    sc_cond_signal(&resizer->req_cond);
-    sc_mutex_unlock(&resizer->mutex);
-}

app/src/resizer.h

@@ -1,53 +0,0 @@
-#ifndef SC_RESIZER
-#define SC_RESIZER
-
-#include "common.h"
-
-#include <stdbool.h>
-#include <libavformat/avformat.h>
-
-#include "coords.h"
-#include "util/thread.h"
-#include "video_buffer.h"
-
-struct sc_resizer {
-    struct video_buffer *vb_in;
-    struct video_buffer *vb_out;
-    struct size size;
-
-    // valid until the next call to video_buffer_consumer_take_frame(vb_in)
-    const AVFrame *input_frame;
-    AVFrame *resized_frame;
-
-    sc_thread thread;
-    sc_mutex mutex;
-    sc_cond req_cond;
-
-    bool has_request;
-    bool has_new_frame;
-    bool interrupted;
-};
-
-bool
-sc_resizer_init(struct sc_resizer *resizer, struct video_buffer *vb_in,
-                struct video_buffer *vb_out, struct size initial_size);
-
-void
-sc_resizer_destroy(struct sc_resizer *resizer);
-
-bool
-sc_resizer_start(struct sc_resizer *resizer);
-
-void
-sc_resizer_stop(struct sc_resizer *resizer);
-
-void
-sc_resizer_join(struct sc_resizer *resizer);
-
-void
-sc_resizer_process_new_frame(struct sc_resizer *resizer);
-
-void
-sc_resizer_process_new_size(struct sc_resizer *resizer, struct size size);
-
-#endif

app/src/scrcpy.c

@@ -42,7 +42,6 @@ static struct file_handler file_handler;
 static struct input_manager input_manager = {
     .controller = &controller,
     .video_buffer = &video_buffer,
-    .fps_counter = &fps_counter,
     .screen = &screen,
     .repeat = 0,
 
@@ -267,6 +266,14 @@ av_log_callback(void *avcl, int level, const char *fmt, va_list vl) {
     free(local_fmt);
 }
 
+static void
+decoder_on_new_frame(struct decoder *decoder, void *userdata) {
+    (void) decoder;
+    (void) userdata;
+
+    screen_on_new_frame(&screen);
+}
+
 bool
 scrcpy(const struct scrcpy_options *options) {
     if (!server_init(&server)) {
@@ -333,7 +340,8 @@ scrcpy(const struct scrcpy_options *options) {
         }
         fps_counter_initialized = true;
 
-        if (!video_buffer_init(&video_buffer, options->render_expired_frames)) {
+        if (!video_buffer_init(&video_buffer, &fps_counter,
+                               options->render_expired_frames)) {
             goto end;
         }
         video_buffer_initialized = true;
@@ -346,7 +354,11 @@ scrcpy(const struct scrcpy_options *options) {
             file_handler_initialized = true;
         }
 
-        decoder_init(&decoder, &video_buffer);
+        static const struct decoder_callbacks decoder_cbs = {
+            .on_new_frame = decoder_on_new_frame,
+        };
+
+        decoder_init(&decoder, &video_buffer, &decoder_cbs, NULL);
         dec = &decoder;
     }
 
@@ -366,6 +378,13 @@ scrcpy(const struct scrcpy_options *options) {
 
     stream_init(&stream, server.video_socket, dec, rec);
 
+    // now we consumed the header values, the socket receives the video stream
+    // start the stream
+    if (!stream_start(&stream)) {
+        goto end;
+    }
+    stream_started = true;
+
     if (options->display) {
         if (options->control) {
             if (!controller_init(&controller, server.control_socket)) {
@@ -382,21 +401,14 @@ scrcpy(const struct scrcpy_options *options) {
         const char *window_title =
             options->window_title ? options->window_title : device_name;
 
-        struct screen_params screen_params = {
-            .window_title = window_title,
-            .frame_size = frame_size,
-            .always_on_top = options->always_on_top,
-            .window_x = options->window_x,
-            .window_y = options->window_y,
-            .window_width = options->window_width,
-            .window_height = options->window_height,
-            .window_borderless = options->window_borderless,
-            .rotation = options->rotation,
-            .scale_filter = options->scale_filter,
-        };
+        screen_init(&screen, &video_buffer);
 
-        if (!screen_init(&screen, &video_buffer, &fps_counter,
-                         &screen_params)) {
+        if (!screen_init_rendering(&screen, window_title, frame_size,
+                                   options->always_on_top, options->window_x,
+                                   options->window_y, options->window_width,
+                                   options->window_height,
+                                   options->window_borderless,
+                                   options->rotation, options->scale_filter)) {
             goto end;
         }
 
@@ -415,13 +427,6 @@ scrcpy(const struct scrcpy_options *options) {
         }
     }
 
-    // now we consumed the header values, the socket receives the video stream
-    // start the stream
-    if (!stream_start(&stream)) {
-        goto end;
-    }
-    stream_started = true;
-
     input_manager_init(&input_manager, options);
 
     ret = event_loop(options);

app/src/scrcpy.h

@@ -109,10 +109,10 @@ struct scrcpy_options {
         .count = 2, \
     }, \
     .scale_filter = SC_SCALE_FILTER_TRILINEAR, \
-    .max_size = 0, \
+    .max_size = DEFAULT_MAX_SIZE, \
     .bit_rate = DEFAULT_BIT_RATE, \
     .max_fps = 0, \
-    .lock_video_orientation = -1, \
+    .lock_video_orientation = DEFAULT_LOCK_VIDEO_ORIENTATION, \
     .rotation = 0, \
     .window_x = SC_WINDOW_POSITION_UNDEFINED, \
     .window_y = SC_WINDOW_POSITION_UNDEFINED, \

app/src/screen.c

@@ -190,25 +190,10 @@ screen_update_content_rect(struct screen *screen) {
     }
 }
 
-static void
-on_frame_available(struct video_buffer *vb, void *userdata) {
-    (void) vb;
-    (void) userdata;
-
-    static SDL_Event new_frame_event = {
-        .type = EVENT_NEW_FRAME,
-    };
-
-    // Post the event on the UI thread
-    SDL_PushEvent(&new_frame_event);
-}
-
-static void
-on_frame_skipped(struct video_buffer *vb, void *userdata) {
-    (void) vb;
-
-    struct screen *screen = userdata;
-    fps_counter_add_skipped_frame(screen->fps_counter);
+void
+screen_init(struct screen *screen, struct video_buffer *vb) {
+    *screen = (struct screen) SCREEN_INITIALIZER;
+    screen->vb = vb;
 }
 
 static inline SDL_Texture *
@@ -239,40 +224,26 @@ create_texture(struct screen *screen) {
 }
 
 bool
-screen_init(struct screen *screen, struct video_buffer *vb,
-            struct fps_counter *fps_counter,
-            const struct screen_params *params) {
-    screen->vb = vb;
-    screen->fps_counter = fps_counter;
-
-    screen->resize_pending = false;
-    screen->has_frame = false;
-    screen->fullscreen = false;
-    screen->maximized = false;
-
-    static const struct video_buffer_callbacks cbs = {
-        .on_frame_available = on_frame_available,
-        .on_frame_skipped = on_frame_skipped,
-    };
-    video_buffer_set_consumer_callbacks(vb, &cbs, screen);
-
-    screen->frame_size = params->frame_size;
-    screen->rotation = params->rotation;
-    if (screen->rotation) {
-        LOGI("Initial display rotation set to %u", screen->rotation);
+screen_init_rendering(struct screen *screen, const char *window_title,
+                      struct size frame_size, bool always_on_top,
+                      int16_t window_x, int16_t window_y, uint16_t window_width,
+                      uint16_t window_height, bool window_borderless,
+                      uint8_t rotation, enum sc_scale_filter scale_filter) {
+    screen->frame_size = frame_size;
+    screen->rotation = rotation;
+    if (rotation) {
+        LOGI("Initial display rotation set to %u", rotation);
     }
-    struct size content_size =
-        get_rotated_size(screen->frame_size, screen->rotation);
+    struct size content_size = get_rotated_size(frame_size, screen->rotation);
     screen->content_size = content_size;
 
-    struct size window_size = get_initial_optimal_size(content_size,
-                                                       params->window_width,
-                                                       params->window_height);
+    struct size window_size =
+        get_initial_optimal_size(content_size, window_width, window_height);
     uint32_t window_flags = SDL_WINDOW_HIDDEN | SDL_WINDOW_RESIZABLE;
 #ifdef HIDPI_SUPPORT
     window_flags |= SDL_WINDOW_ALLOW_HIGHDPI;
 #endif
-    if (params->always_on_top) {
+    if (always_on_top) {
 #ifdef SCRCPY_SDL_HAS_WINDOW_ALWAYS_ON_TOP
         window_flags |= SDL_WINDOW_ALWAYS_ON_TOP;
 #else
@@ -280,15 +251,15 @@ screen_init(struct screen *screen, struct video_buffer *vb,
              "(compile with SDL >= 2.0.5 to enable it)");
 #endif
     }
-    if (params->window_borderless) {
+    if (window_borderless) {
         window_flags |= SDL_WINDOW_BORDERLESS;
     }
 
-    int x = params->window_x != SC_WINDOW_POSITION_UNDEFINED
-          ? params->window_x : (int) SDL_WINDOWPOS_UNDEFINED;
-    int y = params->window_y != SC_WINDOW_POSITION_UNDEFINED
-          ? params->window_y : (int) SDL_WINDOWPOS_UNDEFINED;
-    screen->window = SDL_CreateWindow(params->window_title, x, y,
+    int x = window_x != SC_WINDOW_POSITION_UNDEFINED
+          ? window_x : (int) SDL_WINDOWPOS_UNDEFINED;
+    int y = window_y != SC_WINDOW_POSITION_UNDEFINED
+          ? window_y : (int) SDL_WINDOWPOS_UNDEFINED;
+    screen->window = SDL_CreateWindow(window_title, x, y,
                                       window_size.width, window_size.height,
                                       window_flags);
     if (!screen->window) {
@@ -309,11 +280,9 @@ screen_init(struct screen *screen, struct video_buffer *vb,
     const char *renderer_name = r ? NULL : renderer_info.name;
     LOGI("Renderer: %s", renderer_name ? renderer_name : "(unknown)");
 
-    screen->mipmaps = false;
-
     // starts with "opengl"
     bool use_opengl = renderer_name && !strncmp(renderer_name, "opengl", 6);
-    bool mipmaps = params->scale_filter == SC_SCALE_FILTER_TRILINEAR;
+    bool mipmaps = scale_filter == SC_SCALE_FILTER_TRILINEAR;
     if (use_opengl) {
         struct sc_opengl *gl = &screen->gl;
         sc_opengl_init(gl);
@@ -346,22 +315,14 @@ screen_init(struct screen *screen, struct video_buffer *vb,
         LOGW("Could not load icon");
     }
 
-    LOGI("Initial texture: %" PRIu16 "x%" PRIu16, params->frame_size.width,
-                                                  params->frame_size.height);
+    LOGI("Initial texture: %" PRIu16 "x%" PRIu16, frame_size.width,
+                                                  frame_size.height);
     screen->texture = create_texture(screen);
     if (!screen->texture) {
         LOGC("Could not create texture: %s", SDL_GetError());
         SDL_DestroyRenderer(screen->renderer);
         SDL_DestroyWindow(screen->window);
-        return false;
-    }
-
-    screen->frame = av_frame_alloc();
-    if (!screen->frame) {
-        LOGC("Could not create screen frame");
-        SDL_DestroyTexture(screen->texture);
-        SDL_DestroyRenderer(screen->renderer);
-        SDL_DestroyWindow(screen->window);
+        screen_destroy(screen);
         return false;
     }
 
@@ -382,8 +343,9 @@ screen_show_window(struct screen *screen) {
 
 void
 screen_destroy(struct screen *screen) {
-    av_frame_free(&screen->frame);
-    SDL_DestroyTexture(screen->texture);
+    if (screen->texture) {
+        SDL_DestroyTexture(screen->texture);
+    }
     SDL_DestroyRenderer(screen->renderer);
     SDL_DestroyWindow(screen->window);
 }
@@ -490,11 +452,7 @@ update_texture(struct screen *screen, const AVFrame *frame) {
 
 static bool
 screen_update_frame(struct screen *screen) {
-    video_buffer_consumer_take_frame(screen->vb, &screen->frame);
-    AVFrame *frame = screen->frame;
-
-    fps_counter_add_rendered_frame(screen->fps_counter);
-
+    const AVFrame *frame = video_buffer_take_rendering_frame(screen->vb);
     struct size new_frame_size = {frame->width, frame->height};
     if (!prepare_for_frame(screen, new_frame_size)) {
         return false;
@@ -689,3 +647,15 @@ screen_hidpi_scale_coords(struct screen *screen, int32_t *x, int32_t *y) {
     *x = (int64_t) *x * dw / ww;
     *y = (int64_t) *y * dh / wh;
 }
+
+void
+screen_on_new_frame(struct screen *screen) {
+    (void) screen;
+
+    static SDL_Event new_frame_event = {
+        .type = EVENT_NEW_FRAME,
+    };
+
+    // Post the event on the UI thread
+    SDL_PushEvent(&new_frame_event);
+}

app/src/screen.h

@@ -15,8 +15,6 @@ struct video_buffer;
 
 struct screen {
     struct video_buffer *vb;
-    struct fps_counter *fps_counter;
-
     SDL_Window *window;
     SDL_Renderer *renderer;
     SDL_Texture *texture;
@@ -36,32 +34,55 @@ struct screen {
     bool has_frame;
     bool fullscreen;
     bool maximized;
+    bool no_window;
     bool mipmaps;
-
-    AVFrame *frame;
 };
 
-struct screen_params {
-    const char *window_title;
-    struct size frame_size;
-    bool always_on_top;
+#define SCREEN_INITIALIZER { \
+    .vb = NULL, \
+    .window = NULL, \
+    .renderer = NULL, \
+    .texture = NULL, \
+    .gl = {0}, \
+    .frame_size = { \
+        .width = 0, \
+        .height = 0, \
+    }, \
+    .content_size = { \
+        .width = 0, \
+        .height = 0, \
+    }, \
+    .resize_pending = false, \
+    .windowed_content_size = { \
+        .width = 0, \
+        .height = 0, \
+    }, \
+    .rotation = 0, \
+    .rect = { \
+        .x = 0, \
+        .y = 0, \
+        .w = 0, \
+        .h = 0, \
+    }, \
+    .has_frame = false, \
+    .fullscreen = false, \
+    .maximized = false, \
+    .no_window = false, \
+    .mipmaps = false, \
+}
 
-    int16_t window_x;
-    int16_t window_y;
-    uint16_t window_width;  // accepts SC_WINDOW_POSITION_UNDEFINED
-    uint16_t window_height; // accepts SC_WINDOW_POSITION_UNDEFINED
-
-    bool window_borderless;
-
-    uint8_t rotation;
-    enum sc_scale_filter scale_filter;
-};
+// initialize default values
+void
+screen_init(struct screen *screen, struct video_buffer *vb);
 
 // initialize screen, create window, renderer and texture (window is hidden)
+// window_x and window_y accept SC_WINDOW_POSITION_UNDEFINED
 bool
-screen_init(struct screen *screen, struct video_buffer *vb,
-            struct fps_counter *fps_counter,
-            const struct screen_params *params);
+screen_init_rendering(struct screen *screen, const char *window_title,
+                      struct size frame_size, bool always_on_top,
+                      int16_t window_x, int16_t window_y, uint16_t window_width,
+                      uint16_t window_height, bool window_borderless,
+                      uint8_t rotation, enum sc_scale_filter scale_filter);
 
 // show the window
 void
@@ -117,4 +138,9 @@ screen_convert_drawable_to_frame_coords(struct screen *screen,
 void
 screen_hidpi_scale_coords(struct screen *screen, int32_t *x, int32_t *y);
 
+// Notify the screen that a new frame is available in the video_buffer.
+// Called from a separate thread.
+void
+screen_on_new_frame(struct screen *screen);
+
 #endif

app/src/video_buffer.c

@@ -7,118 +7,129 @@
 #include "util/log.h"
 
 bool
-video_buffer_init(struct video_buffer *vb, bool wait_consumer) {
+video_buffer_init(struct video_buffer *vb, struct fps_counter *fps_counter,
+                  bool render_expired_frames) {
+    vb->fps_counter = fps_counter;
+
+    vb->decoding_frame = av_frame_alloc();
+    if (!vb->decoding_frame) {
+        goto error_0;
+    }
+
     vb->pending_frame = av_frame_alloc();
     if (!vb->pending_frame) {
-        goto error_0;
+        goto error_1;
+    }
+
+    vb->rendering_frame = av_frame_alloc();
+    if (!vb->rendering_frame) {
+        goto error_2;
     }
 
     bool ok = sc_mutex_init(&vb->mutex);
     if (!ok) {
-        goto error_1;
+        goto error_3;
     }
 
-    vb->wait_consumer = wait_consumer;
-    if (wait_consumer) {
+    vb->render_expired_frames = render_expired_frames;
+    if (render_expired_frames) {
         ok = sc_cond_init(&vb->pending_frame_consumed_cond);
         if (!ok) {
             sc_mutex_destroy(&vb->mutex);
-            goto error_1;
+            goto error_2;
         }
-        // interrupted is not used if wait_consumer is disabled since offering
-        // a frame will never block
+        // interrupted is not used if expired frames are not rendered
+        // since offering a frame will never block
         vb->interrupted = false;
     }
 
-    // there is initially no frame, so consider it has already been consumed
+    // there is initially no rendering frame, so consider it has already been
+    // consumed
     vb->pending_frame_consumed = true;
 
-    // The callbacks must be set by the consumer via
-    // video_buffer_set_consumer_callbacks()
-    vb->cbs = NULL;
-
     return true;
 
-error_1:
+error_3:
+    av_frame_free(&vb->rendering_frame);
+error_2:
     av_frame_free(&vb->pending_frame);
+error_1:
+    av_frame_free(&vb->decoding_frame);
 error_0:
     return false;
 }
 
 void
 video_buffer_destroy(struct video_buffer *vb) {
-    if (vb->wait_consumer) {
+    if (vb->render_expired_frames) {
         sc_cond_destroy(&vb->pending_frame_consumed_cond);
     }
     sc_mutex_destroy(&vb->mutex);
+    av_frame_free(&vb->rendering_frame);
     av_frame_free(&vb->pending_frame);
+    av_frame_free(&vb->decoding_frame);
 }
 
-static inline void
-swap_frames(AVFrame **lhs, AVFrame **rhs) {
-    AVFrame *tmp = *lhs;
-    *lhs = *rhs;
-    *rhs = tmp;
+static void
+video_buffer_swap_decoding_frame(struct video_buffer *vb) {
+    sc_mutex_assert(&vb->mutex);
+    AVFrame *tmp = vb->decoding_frame;
+    vb->decoding_frame = vb->pending_frame;
+    vb->pending_frame = tmp;
+}
+
+static void
+video_buffer_swap_rendering_frame(struct video_buffer *vb) {
+    sc_mutex_assert(&vb->mutex);
+    AVFrame *tmp = vb->rendering_frame;
+    vb->rendering_frame = vb->pending_frame;
+    vb->pending_frame = tmp;
 }
 
 void
-video_buffer_set_consumer_callbacks(struct video_buffer *vb,
-                                    const struct video_buffer_callbacks *cbs,
-                                    void *cbs_userdata) {
-    assert(!vb->cbs); // must be set only once
-    assert(cbs);
-    assert(cbs->on_frame_available);
-    vb->cbs = cbs;
-    vb->cbs_userdata = cbs_userdata;
-}
-
-void
-video_buffer_producer_offer_frame(struct video_buffer *vb, AVFrame **pframe) {
-    assert(vb->cbs);
-
+video_buffer_offer_decoded_frame(struct video_buffer *vb,
+                                 bool *previous_frame_skipped) {
     sc_mutex_lock(&vb->mutex);
-    if (vb->wait_consumer) {
+    if (vb->render_expired_frames) {
         // wait for the current (expired) frame to be consumed
         while (!vb->pending_frame_consumed && !vb->interrupted) {
             sc_cond_wait(&vb->pending_frame_consumed_cond, &vb->mutex);
         }
+    } else if (!vb->pending_frame_consumed) {
+        fps_counter_add_skipped_frame(vb->fps_counter);
     }
 
-    av_frame_unref(vb->pending_frame);
-    swap_frames(pframe, &vb->pending_frame);
+    video_buffer_swap_decoding_frame(vb);
 
-    bool skipped = !vb->pending_frame_consumed;
+    *previous_frame_skipped = !vb->pending_frame_consumed;
     vb->pending_frame_consumed = false;
 
     sc_mutex_unlock(&vb->mutex);
-
-    if (skipped) {
-        if (vb->cbs->on_frame_skipped)
-            vb->cbs->on_frame_skipped(vb, vb->cbs_userdata);
-    } else {
-        vb->cbs->on_frame_available(vb, vb->cbs_userdata);
-    }
 }
 
-void
-video_buffer_consumer_take_frame(struct video_buffer *vb, AVFrame **pframe) {
+const AVFrame *
+video_buffer_take_rendering_frame(struct video_buffer *vb) {
     sc_mutex_lock(&vb->mutex);
     assert(!vb->pending_frame_consumed);
     vb->pending_frame_consumed = true;
 
-    swap_frames(pframe, &vb->pending_frame);
-    av_frame_unref(vb->pending_frame);
+    fps_counter_add_rendered_frame(vb->fps_counter);
 
-    if (vb->wait_consumer) {
+    video_buffer_swap_rendering_frame(vb);
+
+    if (vb->render_expired_frames) {
         // unblock video_buffer_offer_decoded_frame()
         sc_cond_signal(&vb->pending_frame_consumed_cond);
     }
     sc_mutex_unlock(&vb->mutex);
+
+    // rendering_frame is only written from this thread, no need to lock
+    return vb->rendering_frame;
 }
 
 void
 video_buffer_interrupt(struct video_buffer *vb) {
-    if (vb->wait_consumer) {
+    if (vb->render_expired_frames) {
         sc_mutex_lock(&vb->mutex);
         vb->interrupted = true;
         sc_mutex_unlock(&vb->mutex);

app/src/video_buffer.h

@@ -13,66 +13,53 @@ typedef struct AVFrame AVFrame;
 
 /**
  * There are 3 frames in memory:
- *  - one frame is held by the producer (producer_frame)
- *  - one frame is held by the consumer (consumer_frame)
- *  - one frame is shared between the producer and the consumer (pending_frame)
+ *  - one frame is held by the decoder (decoding_frame)
+ *  - one frame is held by the renderer (rendering_frame)
+ *  - one frame is shared between the decoder and the renderer (pending_frame)
  *
- * The producer generates a frame into the producer_frame (it may takes time).
+ * The decoder decodes a packet into the decoding_frame (it may takes time).
  *
- * Once the frame is produced, it calls video_buffer_producer_offer_frame(),
- * which swaps the producer and pending frames.
+ * Once the frame is decoded, it calls video_buffer_offer_decoded_frame(),
+ * which swaps the decoding and pending frames.
  *
- * When the consumer is notified that a new frame is available, it calls
- * video_buffer_consumer_take_frame() to retrieve it, which swaps the pending
- * and consumer frames. The frame is valid until the next call, without
- * blocking the producer.
+ * When the renderer is notified that a new frame is available, it calls
+ * video_buffer_take_rendering_frame() to retrieve it, which swaps the pending
+ * and rendering frames. The frame is valid until the next call, without
+ * blocking the decoder.
  */
 
 struct video_buffer {
+    AVFrame *decoding_frame;
     AVFrame *pending_frame;
+    AVFrame *rendering_frame;
 
     sc_mutex mutex;
-    bool wait_consumer; // never overwrite a pending frame if it is not consumed
+    bool render_expired_frames;
     bool interrupted;
 
     sc_cond pending_frame_consumed_cond;
     bool pending_frame_consumed;
 
-    const struct video_buffer_callbacks *cbs;
-    void *cbs_userdata;
-};
-
-struct video_buffer_callbacks {
-    // Called when a new frame can be consumed by
-    // video_buffer_consumer_take_frame(vb)
-    // This callback is mandatory (it must not be NULL).
-    void (*on_frame_available)(struct video_buffer *vb, void *userdata);
-
-    // Called when a pending frame has been overwritten by the producer
-    // This callback is optional (it may be NULL).
-    void (*on_frame_skipped)(struct video_buffer *vb, void *userdata);
+    struct fps_counter *fps_counter;
 };
 
 bool
-video_buffer_init(struct video_buffer *vb, bool wait_consumer);
+video_buffer_init(struct video_buffer *vb, struct fps_counter *fps_counter,
+                  bool render_expired_frames);
 
 void
 video_buffer_destroy(struct video_buffer *vb);
 
+// set the decoded frame as ready for rendering
+// the output flag is set to report whether the previous frame has been skipped
 void
-video_buffer_set_consumer_callbacks(struct video_buffer *vb,
-                                    const struct video_buffer_callbacks *cbs,
-                                    void *cbs_userdata);
+video_buffer_offer_decoded_frame(struct video_buffer *vb,
+                                 bool *previous_frame_skipped);
 
-// set the producer frame as ready for consuming
-// the produced frame is exchanged with an unused allocated frame
-void
-video_buffer_producer_offer_frame(struct video_buffer *vb, AVFrame **pframe);
-
-// mark the consumer frame as consumed and exchange it with an unused allocated
-// frame
-void
-video_buffer_consumer_take_frame(struct video_buffer *vb, AVFrame **pframe);
+// mark the rendering frame as consumed and return it
+// the frame is valid until the next call to this function
+const AVFrame *
+video_buffer_take_rendering_frame(struct video_buffer *vb);
 
 // wake up and avoid any blocking call
 void