avformat/async: support filling with a background thread.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

configure

@@ -2654,6 +2654,7 @@ x11grab_indev_deps="x11grab"
 x11grab_xcb_indev_deps="libxcb"
 
 # protocols
+async_protocol_deps="pthreads"
 bluray_protocol_deps="libbluray"
 ffrtmpcrypt_protocol_deps="!librtmp_protocol"
 ffrtmpcrypt_protocol_deps_any="gcrypt gmp openssl"

doc/protocols.texi

@@ -19,6 +19,18 @@ supported protocols.
 
 A description of the currently available protocols follows.
 
+@section async
+
+Asynchronous data filling wrapper for input stream.
+
+Fill data in a background thread, to decouple I/O operation from demux thread.
+
+@example
+async:@var{URL}
+async:http://host/resource
+async:cache:http://host/resource
+@end example
+
 @section bluray
 
 Read BluRay playlist.

libavformat/Makefile

@@ -496,6 +496,7 @@ OBJS-$(CONFIG_LIBSSH_PROTOCOL)           += libssh.o
 OBJS-$(CONFIG_LIBSMBCLIENT_PROTOCOL)     += libsmbclient.o
 
 # protocols I/O
+OBJS-$(CONFIG_ASYNC_PROTOCOL)            += async.o
 OBJS-$(CONFIG_APPLEHTTP_PROTOCOL)        += hlsproto.o
 OBJS-$(CONFIG_BLURAY_PROTOCOL)           += bluray.o
 OBJS-$(CONFIG_CACHE_PROTOCOL)            += cache.o

libavformat/allformats.c

@@ -351,6 +351,7 @@ void av_register_all(void)
 
 
     /* protocols */
+    REGISTER_PROTOCOL(ASYNC,            async);
     REGISTER_PROTOCOL(BLURAY,           bluray);
     REGISTER_PROTOCOL(CACHE,            cache);
     REGISTER_PROTOCOL(CONCAT,           concat);