Introduce packet source trait

There was a packet sink trait, implemented by components able to
receive AVPackets, but each packet source had to manually send packets
to sinks.

In order to mutualise sink management, add a packet source trait.

app/meson.build

@@ -30,6 +30,7 @@ src = [
     'src/server.c',
     'src/version.c',
     'src/video_buffer.c',
+    'src/trait/packet_source.c',
     'src/util/acksync.c',
     'src/util/bytebuf.c',
     'src/util/file.c',

app/src/trait/packet_source.c

@@ -0,0 +1,70 @@
+#include "packet_source.h"
+
+void
+sc_packet_source_init(struct sc_packet_source *source) {
+    source->sink_count = 0;
+}
+
+void
+sc_packet_source_add_sink(struct sc_packet_source *source,
+                          struct sc_packet_sink *sink) {
+    assert(source->sink_count < SC_PACKET_SOURCE_MAX_SINKS);
+    assert(sink);
+    assert(sink->ops);
+    source->sinks[source->sink_count++] = sink;
+}
+
+static void
+sc_packet_source_sinks_close_firsts(struct sc_packet_source *source,
+                                    unsigned count) {
+    while (count) {
+        struct sc_packet_sink *sink = source->sinks[--count];
+        sink->ops->close(sink);
+    }
+}
+
+bool
+sc_packet_source_sinks_open(struct sc_packet_source *source,
+                            const AVCodec *codec) {
+    assert(source->sink_count);
+    for (unsigned i = 0; i < source->sink_count; ++i) {
+        struct sc_packet_sink *sink = source->sinks[i];
+        if (!sink->ops->open(sink, codec)) {
+            sc_packet_source_sinks_close_firsts(source, i);
+            return false;
+        }
+    }
+
+    return true;
+}
+
+void
+sc_packet_source_sinks_close(struct sc_packet_source *source) {
+    assert(source->sink_count);
+    sc_packet_source_sinks_close_firsts(source, source->sink_count);
+}
+
+bool
+sc_packet_source_sinks_push(struct sc_packet_source *source,
+                            const AVPacket *packet) {
+    assert(source->sink_count);
+    for (unsigned i = 0; i < source->sink_count; ++i) {
+        struct sc_packet_sink *sink = source->sinks[i];
+        if (!sink->ops->push(sink, packet)) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+void
+sc_packet_source_sinks_disable(struct sc_packet_source *source) {
+    assert(source->sink_count);
+    for (unsigned i = 0; i < source->sink_count; ++i) {
+        struct sc_packet_sink *sink = source->sinks[i];
+        if (sink->ops->disable) {
+            sink->ops->disable(sink);
+        }
+    }
+}

app/src/trait/packet_source.h

@@ -0,0 +1,41 @@
+#ifndef SC_PACKET_SOURCE_H
+#define SC_PACKET_SOURCE_H
+
+#include "common.h"
+
+#include "packet_sink.h"
+
+#define SC_PACKET_SOURCE_MAX_SINKS 2
+
+/**
+ * Packet source trait
+ *
+ * Component able to send AVPackets should implement this trait.
+ */
+struct sc_packet_source {
+    struct sc_packet_sink *sinks[SC_PACKET_SOURCE_MAX_SINKS];
+    unsigned sink_count;
+};
+
+void
+sc_packet_source_init(struct sc_packet_source *source);
+
+void
+sc_packet_source_add_sink(struct sc_packet_source *source,
+                          struct sc_packet_sink *sink);
+
+bool
+sc_packet_source_sinks_open(struct sc_packet_source *source,
+                            const AVCodec *codec);
+
+void
+sc_packet_source_sinks_close(struct sc_packet_source *source);
+
+bool
+sc_packet_source_sinks_push(struct sc_packet_source *source,
+                            const AVPacket *packet);
+
+void
+sc_packet_source_sinks_disable(struct sc_packet_source *source);
+
+#endif