buffering_thread

app/src/screen.c

@@ -308,15 +308,21 @@ screen_init(struct screen *screen, const struct screen_params *params) {
         .on_new_frame = sc_video_buffer_on_new_frame,
     };
 
-    bool ok = sc_video_buffer_init(&screen->vb, &cbs, screen);
+    bool ok = sc_video_buffer_init(&screen->vb, 0, &cbs, screen);
     if (!ok) {
         LOGE("Could not initialize video buffer");
         return false;
     }
 
+    ok = sc_video_buffer_start(&screen->vb);
+    if (!ok) {
+        LOGE("Could not start video_buffer");
+        goto error_destroy_video_buffer;
+    }
+
     if (!fps_counter_init(&screen->fps_counter)) {
         LOGE("Could not initialize FPS counter");
-        goto error_destroy_video_buffer;
+        goto error_stop_and_join_video_buffer;
     }
 
     screen->frame_size = params->frame_size;
@@ -457,6 +463,9 @@ error_destroy_window:
     SDL_DestroyWindow(screen->window);
 error_destroy_fps_counter:
     fps_counter_destroy(&screen->fps_counter);
+error_stop_and_join_video_buffer:
+    sc_video_buffer_stop(&screen->vb);
+    sc_video_buffer_join(&screen->vb);
 error_destroy_video_buffer:
     sc_video_buffer_destroy(&screen->vb);
 
@@ -475,11 +484,13 @@ screen_hide_window(struct screen *screen) {
 
 void
 screen_interrupt(struct screen *screen) {
+    sc_video_buffer_stop(&screen->vb);
     fps_counter_interrupt(&screen->fps_counter);
 }
 
 void
 screen_join(struct screen *screen) {
+    sc_video_buffer_join(&screen->vb);
     fps_counter_join(&screen->fps_counter);
 }
 

app/src/v4l2_sink.c

@@ -159,16 +159,22 @@ sc_v4l2_sink_open(struct sc_v4l2_sink *vs) {
         .on_new_frame = sc_video_buffer_on_new_frame,
     };
 
-    bool ok = sc_video_buffer_init(&vs->vb, &cbs, vs);
+    bool ok = sc_video_buffer_init(&vs->vb, 0, &cbs, vs);
     if (!ok) {
         LOGE("Could not initialize video buffer");
         return false;
     }
 
+    ok = sc_video_buffer_start(&vs->vb);
+    if (!ok) {
+        LOGE("Could not start video buffer");
+        goto error_video_buffer_destroy;
+    }
+
     ok = sc_mutex_init(&vs->mutex);
     if (!ok) {
         LOGC("Could not create mutex");
-        goto error_video_buffer_destroy;
+        goto error_video_buffer_stop_and_join;
     }
 
     ok = sc_cond_init(&vs->cond);
@@ -293,6 +299,9 @@ error_cond_destroy:
     sc_cond_destroy(&vs->cond);
 error_mutex_destroy:
     sc_mutex_destroy(&vs->mutex);
+error_video_buffer_stop_and_join:
+    sc_video_buffer_stop(&vs->vb);
+    sc_video_buffer_join(&vs->vb);
 error_video_buffer_destroy:
     sc_video_buffer_destroy(&vs->vb);
 
@@ -306,7 +315,10 @@ sc_v4l2_sink_close(struct sc_v4l2_sink *vs) {
     sc_cond_signal(&vs->cond);
     sc_mutex_unlock(&vs->mutex);
 
+    sc_video_buffer_stop(&vs->vb);
+
     sc_thread_join(&vs->thread, NULL);
+    sc_video_buffer_join(&vs->vb);
 
     av_packet_free(&vs->packet);
     av_frame_free(&vs->frame);

app/src/video_buffer.c

@@ -6,30 +6,37 @@
 
 #include "util/log.h"
 
-bool
-sc_video_buffer_init(struct sc_video_buffer *vb,
-                     const struct sc_video_buffer_callbacks *cbs,
-                     void *cbs_userdata) {
-    bool ok = sc_frame_buffer_init(&vb->fb);
-    if (!ok) {
-        return false;
+static struct sc_video_buffer_frame *
+sc_video_buffer_frame_new(const AVFrame *frame) {
+    struct sc_video_buffer_frame *vb_frame = malloc(sizeof(*vb_frame));
+    if (!vb_frame) {
+        return NULL;
     }
 
-    assert(cbs);
-    assert(cbs->on_new_frame);
+    vb_frame->frame = av_frame_alloc();
+    if (!vb_frame->frame) {
+        free(vb_frame);
+        return NULL;
+    }
 
-    vb->cbs = cbs;
-    vb->cbs_userdata = cbs_userdata;
-    return true;
+    if (av_frame_ref(vb_frame->frame, frame)) {
+        av_frame_free(&vb_frame->frame);
+        free(vb_frame);
+        return NULL;
+    }
+
+    return vb_frame;
 }
 
-void
-sc_video_buffer_destroy(struct sc_video_buffer *vb) {
-    sc_frame_buffer_destroy(&vb->fb);
+static void
+sc_video_buffer_frame_delete(struct sc_video_buffer_frame *vb_frame) {
+    av_frame_unref(vb_frame->frame);
+    av_frame_free(&vb_frame->frame);
+    free(vb_frame);
 }
 
-bool
-sc_video_buffer_push(struct sc_video_buffer *vb, const AVFrame *frame) {
+static bool
+sc_video_buffer_offer(struct sc_video_buffer *vb, const AVFrame *frame) {
     bool previous_skipped;
     bool ok = sc_frame_buffer_push(&vb->fb, frame, &previous_skipped);
     if (!ok) {
@@ -40,6 +47,143 @@ sc_video_buffer_push(struct sc_video_buffer *vb, const AVFrame *frame) {
     return true;
 }
 
+static int
+run_buffering(void *data) {
+    struct sc_video_buffer *vb = data;
+
+    assert(vb->buffering_ms);
+
+    for (;;) {
+        sc_mutex_lock(&vb->b.mutex);
+
+        while (!vb->b.stopped && sc_queue_is_empty(&vb->b.queue)) {
+            sc_cond_wait(&vb->b.queue_cond, &vb->b.mutex);
+        }
+
+        if (vb->b.stopped) {
+            // Flush queue
+            while (!sc_queue_is_empty(&vb->b.queue)) {
+                struct sc_video_buffer_frame *vb_frame;
+                sc_queue_take(&vb->b.queue, next, &vb_frame);
+                sc_video_buffer_frame_delete(vb_frame);
+            }
+            break;
+        }
+
+        struct sc_video_buffer_frame *vb_frame;
+        sc_queue_take(&vb->b.queue, next, &vb_frame);
+
+        sc_mutex_unlock(&vb->b.mutex);
+
+        usleep(vb->buffering_ms * 1000);
+
+        sc_video_buffer_offer(vb, vb_frame->frame);
+
+        sc_video_buffer_frame_delete(vb_frame);
+    }
+
+    LOGD("Buffering thread ended");
+
+    return 0;
+}
+
+bool
+sc_video_buffer_init(struct sc_video_buffer *vb, unsigned buffering_ms,
+                     const struct sc_video_buffer_callbacks *cbs,
+                     void *cbs_userdata) {
+    bool ok = sc_frame_buffer_init(&vb->fb);
+    if (!ok) {
+        return false;
+    }
+
+    if (buffering_ms) {
+        ok = sc_mutex_init(&vb->b.mutex);
+        if (!ok) {
+            LOGC("Could not create mutex");
+            sc_frame_buffer_destroy(&vb->fb);
+            return false;
+        }
+
+        ok = sc_cond_init(&vb->b.queue_cond);
+        if (!ok) {
+            LOGC("Could not create cond");
+            sc_mutex_destroy(&vb->b.mutex);
+            sc_frame_buffer_destroy(&vb->fb);
+            return false;
+        }
+
+        sc_queue_init(&vb->b.queue);
+    }
+
+    assert(cbs);
+    assert(cbs->on_new_frame);
+
+    vb->buffering_ms = buffering_ms;
+    vb->cbs = cbs;
+    vb->cbs_userdata = cbs_userdata;
+    return true;
+}
+
+bool
+sc_video_buffer_start(struct sc_video_buffer *vb) {
+    if (vb->buffering_ms) {
+        bool ok =
+            sc_thread_create(&vb->b.thread, run_buffering, "buffering", vb);
+        if (!ok) {
+            LOGE("Could not start buffering thread");
+            return false;
+        }
+    }
+
+    return true;
+}
+
+void
+sc_video_buffer_stop(struct sc_video_buffer *vb) {
+    if (vb->buffering_ms) {
+        sc_mutex_lock(&vb->b.mutex);
+        vb->b.stopped = true;
+        sc_mutex_unlock(&vb->b.mutex);
+    }
+}
+
+void
+sc_video_buffer_join(struct sc_video_buffer *vb) {
+    if (vb->buffering_ms) {
+        sc_thread_join(&vb->b.thread, NULL);
+    }
+}
+
+void
+sc_video_buffer_destroy(struct sc_video_buffer *vb) {
+    sc_frame_buffer_destroy(&vb->fb);
+    if (vb->buffering_ms) {
+        sc_cond_destroy(&vb->b.queue_cond);
+        sc_mutex_destroy(&vb->b.mutex);
+    }
+}
+
+bool
+sc_video_buffer_push(struct sc_video_buffer *vb, const AVFrame *frame) {
+    if (!vb->buffering_ms) {
+        // no buffering
+        return sc_video_buffer_offer(vb, frame);
+    }
+
+    struct sc_video_buffer_frame *vb_frame = sc_video_buffer_frame_new(frame);
+    if (!vb_frame) {
+        LOGE("Could not allocate frame");
+        return false;
+    }
+
+    sc_mutex_lock(&vb->b.mutex);
+    sc_queue_push(&vb->b.queue, next, vb_frame);
+    sc_cond_signal(&vb->b.queue_cond);
+    sc_mutex_unlock(&vb->b.mutex);
+
+    return true;
+}
+
 void
 sc_video_buffer_consume(struct sc_video_buffer *vb, AVFrame *dst) {
     sc_frame_buffer_consume(&vb->fb, dst);

app/src/video_buffer.h

@@ -6,13 +6,33 @@
 #include <stdbool.h>
 
 #include "frame_buffer.h"
+#include "util/queue.h"
+#include "util/thread.h"
 
 // forward declarations
 typedef struct AVFrame AVFrame;
 
+struct sc_video_buffer_frame {
+    AVFrame *frame;
+    struct sc_video_buffer_frame *next;
+};
+
+struct sc_video_buffer_frame_queue SC_QUEUE(struct sc_video_buffer_frame);
+
 struct sc_video_buffer {
     struct sc_frame_buffer fb;
 
+    unsigned buffering_ms;
+
+    // only if buffering_ms > 0
+    struct {
+        sc_thread thread;
+        sc_mutex mutex;
+        sc_cond queue_cond;
+        struct sc_video_buffer_frame_queue queue;
+        bool stopped;
+    } b; // buffering
+
     const struct sc_video_buffer_callbacks *cbs;
     void *cbs_userdata;
 };
@@ -23,10 +43,19 @@ struct sc_video_buffer_callbacks {
 };
 
 bool
-sc_video_buffer_init(struct sc_video_buffer *vb,
+sc_video_buffer_init(struct sc_video_buffer *vb, unsigned buffering_ms,
                      const struct sc_video_buffer_callbacks *cbs,
                      void *cbs_userdata);
 
+bool
+sc_video_buffer_start(struct sc_video_buffer *vb);
+
+void
+sc_video_buffer_stop(struct sc_video_buffer *vb);
+
+void
+sc_video_buffer_join(struct sc_video_buffer *vb);
+
 void
 sc_video_buffer_destroy(struct sc_video_buffer *vb);