[vlc-devel] [PATCH 1/2] access{_out}:srt: introduce SRT input/ouput
Rémi Denis-Courmont
remi at remlab.net
Tue Aug 8 21:13:25 CEST 2017
Hi,
Le keskiviikkona 9. elokuuta 2017, 3.49.17 EEST Justin Kim a écrit :
> Secure Reliable Transport (SRT) is a proprietary transport technology
> that optimizes streaming performance across unpredictable networks.
>
> Signed-off-by: Justin Kim <justin.kim at collabora.com>
> ---
> configure.ac | 29 +++
> modules/access/Makefile.am | 8 +
> modules/access/srt.c | 237 +++++++++++++++++++++
> modules/access_output/Makefile.am | 7 +
> modules/access_output/srt.c | 428
> ++++++++++++++++++++++++++++++++++++++ 5 files changed, 709 insertions(+)
> create mode 100644 modules/access/srt.c
> create mode 100644 modules/access_output/srt.c
>
> diff --git a/configure.ac b/configure.ac
> index 8487fea895..05e01c544f 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -3859,6 +3859,35 @@ AS_IF([test "${enable_lirc}" = "yes"], [
> ])
> AM_CONDITIONAL([HAVE_LIRC], [test "${have_lirc}" = "yes"])
>
> +dnl
> +dnl SRT plugin
> +dnl
> +AC_ARG_ENABLE(srt,
> +[AS_HELP_STRING([--disable-srt],[srt input/output plugin (default auto)])])
> +have_srt="no"
> +AS_IF([test "${enable_srt}" != "no"], [
> + PKG_CHECK_MODULES(SRT, [srt >= 1.2.0], [
> + have_srt="yes"
> + AC_CHECK_HEADER([srt/srt.h], [
> + VLC_ADD_PLUGIN([srt])
> + VLC_ADD_CXXFLAGS([srt], [$SRT_CFLAGS])
> + VLC_ADD_CFLAGS([srt], [$SRT_CFLAGS])
> + VLC_ADD_LIBS([srt], [$SRT_LIBS])
> + ], [
> + AS_IF([test -n "${enable_srt}"],
> + [AC_MSG_ERROR([${SRT_PKG_ERRORS} (required for srt).])],
> + [AC_MSG_WARN([${SRT_PKG_ERRORS} (required for srt).])]
> + )
> + ])
> + ], [
> + AS_IF([test "x${enable_srt}" = "xyes"],
> + [AC_MSG_ERROR([${SRT_PKG_ERRORS} (required for srt).])],
> + [AC_MSG_WARN([${SRT_PKG_ERRORS} (required for srt).])]
> + )
> + ])
Manual header tests are mostly there for old libraries that do not, or did not
support pkg-config. Unless SRT has had significant releases without pkg-
config, this may be overkill.
> +])
> +AM_CONDITIONAL([HAVE_SRT], [test "${have_srt}" = "yes"])
> +
> EXTEND_HELP_STRING([Visualisations and Video filter plugins:])
> dnl
> dnl goom visualization plugin
> diff --git a/modules/access/Makefile.am b/modules/access/Makefile.am
> index dd485a2767..5e765884bc 100644
> --- a/modules/access/Makefile.am
> +++ b/modules/access/Makefile.am
> @@ -417,3 +417,11 @@ libaccess_mtp_plugin_la_LIBADD = $(MTP_LIBS)
> libaccess_mtp_plugin_la_LDFLAGS = $(AM_LDFLAGS) -rpath '$(accessdir)'
> access_LTLIBRARIES += $(LTLIBaccess_mtp)
> EXTRA_LTLIBRARIES += libaccess_mtp_plugin.la
> +
> +### SRT ###
> +
> +libsrt_plugin_la_SOURCES = access/srt.c
> +libsrt_plugin_la_LIBADD = $(SRT_LIBS) $(LIBPTHREAD)
Is there any reasons to pull pthread here? You don´t seem to call any pthread
functions from within the plugin.
> +if HAVE_SRT
> +access_LTLIBRARIES += libsrt_plugin.la
> +endif
> diff --git a/modules/access/srt.c b/modules/access/srt.c
> new file mode 100644
> index 0000000000..8f37232bec
> --- /dev/null
> +++ b/modules/access/srt.c
> @@ -0,0 +1,237 @@
> +/**************************************************************************
> *** + * srt.c: SRT (Secure Reliable Transport) input module
> +
> ***************************************************************************
> ** + * Copyright (C) 2017, Collabora Ltd.
> + *
> + * Authors: Justin Kim <justin.kim at collabora.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU Lesser General Public License as published by
> + * the Free Software Foundation; either version 2.1 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public License
> + * along with this program; if not, write to the Free Software Foundation,
> + * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA. +
> ***************************************************************************
> **/ +
> +#ifdef HAVE_CONFIG_H
> +# include "config.h"
> +#endif
> +
> +#include <errno.h>
> +#include <vlc_common.h>
> +#include <vlc_plugin.h>
> +#include <vlc_access.h>
> +#include <vlc_interface.h>
vlc_interface.h really should not be needed in an input/output plugin.
> +
> +#include <sys/socket.h>
> +#include <netinet/in.h>
> +
> +#include <srt/srt.h>
> +
> +#define SRT_DEFAULT_CHUNK_SIZE 1316
> +
> +static int Open(vlc_object_t *);
> +static void Close(vlc_object_t *);
> +
> +static block_t *BlockSRT( stream_t *, bool * );
> +static int Control( stream_t *, int, va_list );
In new code, I would recommend ordering to avoid forward declarations, with
the descriptor at the end (so like the kernel and gstreamer modules).
> +
> +/* Module descriptor */
> +vlc_module_begin()
> + set_shortname(N_("SRT"))
> + set_description(N_("SRT input"))
> + set_category(CAT_INPUT)
> + set_subcategory( SUBCAT_INPUT_ACCESS )
> +
> + set_capability("access", 0)
> + add_shortcut( "srt" )
> +
> + set_callbacks(Open, Close)
> +vlc_module_end ()
> +
> +struct stream_sys_t
> +{
> + SRTSOCKET sock;
> + int i_poll_id;
> + int i_chunk_size;
size_t ?
> +};
> +
> +static int Open(vlc_object_t *p_this)
> +{
> + stream_t *p_stream = (stream_t*)p_this;
> + stream_sys_t *p_sys;
> +
> + p_sys = vlc_malloc( p_this, sizeof( *p_sys ) );
> + if( unlikely( p_sys == NULL ) )
> + return VLC_ENOMEM;
> +
> + p_sys->i_chunk_size = SRT_DEFAULT_CHUNK_SIZE;
> + p_stream->p_sys = p_sys;
> + p_stream->pf_block = BlockSRT;
> + p_stream->pf_control = Control;
> +
> + p_sys->sock = srt_socket(AF_INET, SOCK_DGRAM, 0);
> + if ( p_sys->sock == SRT_ERROR )
> + {
> + msg_Err( p_stream, "Failed to open socket." );
> + return VLC_EGENERIC;
> + }
I suppose SRT sets the the atomic close-on-flag on all its internal
descriptors?
> +
> + p_sys->i_poll_id = srt_epoll_create();
> + if ( p_sys->i_poll_id == -1 )
> + {
> + msg_Err( p_stream, "Failed to create poll id for SRT socket." );
> + srt_close ( p_sys->sock );
> + return VLC_EGENERIC;
> + }
> + int modes = SRT_EPOLL_OUT;
> + srt_epoll_add_usock( p_sys->i_poll_id, p_sys->sock, &modes );
> +
> + char *psz_name = strdup( p_stream->psz_location );
> + char *psz_parser;
> + const char *psz_server_addr, *psz_bind_addr = "";
> + int i_bind_port = 1234, i_server_port = 0;
> +
> + if( unlikely(psz_name == NULL) )
> + return VLC_ENOMEM;
> +
> + /* Parse psz_name syntax (Copied from udp.c):
> + * [serveraddr[:serverport]][@[bindaddr]:[bindport]] */
> + psz_parser = strchr( psz_name, '@' );
> + if( psz_parser != NULL )
> + {
> + /* Found bind address and/or bind port */
> + *psz_parser++ = '\0';
> + psz_bind_addr = psz_parser;
> +
> + if( psz_bind_addr[0] == '[' )
> + /* skips bracket'd IPv6 address */
> + psz_parser = strchr( psz_parser, ']' );
> +
> + if( psz_parser != NULL )
> + {
> + psz_parser = strchr( psz_parser, ':' );
> + if( psz_parser != NULL )
> + {
> + *psz_parser++ = '\0';
> + i_bind_port = atoi( psz_parser );
> + }
> + }
> + }
> +
> + psz_server_addr = psz_name;
> + psz_parser = ( psz_server_addr[0] == '[' )
> + ? strchr( psz_name, ']' ) /* skips bracket'd IPv6 address */
> + : psz_name;
> +
> + if( psz_parser != NULL )
> + {
> + psz_parser = strchr( psz_parser, ':' );
> + if( psz_parser != NULL )
> + {
> + *psz_parser++ = '\0';
> + i_server_port = atoi( psz_parser );
> + }
> + }
> +
> + msg_Dbg( p_stream, "opening server=%s:%d local=%s:%d",
> + psz_server_addr, i_server_port, psz_bind_addr, i_bind_port );
> +
> + struct sockaddr_in sa;
> + memset( &sa, 0, sizeof sa );
> + sa.sin_family = AF_INET;
> + sa.sin_port = htons( i_server_port );
> +
> + if ( !inet_pton( sa.sin_family, psz_server_addr, &sa.sin_addr ) )
> + {
> + msg_Err( p_stream, "Failed to convert server address(%s).",
> psz_server_addr );
> + srt_close ( p_sys->sock );
> + return VLC_EGENERIC;
> + }
If this really is IPv4-specific, then you should probably drop all the
unnecessary brackets handling above. If it isn´t, then vlc_getaddrinfo() with
the numeric flag is probably simpler.
> +
> + free( psz_name );
> +
> + int stat;
> + struct sockaddr *p_sa = (struct sockaddr*)&sa;
> + stat = srt_connect( p_sys->sock, p_sa, sizeof sa);
How long does this potentially block the calling thread?
Eventually, this probably should call vlc_interrupt_register()/
vlc_interrupt_unregister() or whatever to abort the SRT event loop.
> +
> + if ( stat == SRT_ERROR )
> + {
> + msg_Err( p_stream, "Failed to connect to server." );
> + srt_close ( p_sys->sock );
> + return VLC_EGENERIC;
> + }
> +
> + return VLC_SUCCESS;
> +}
> +
> +static void Close(vlc_object_t *p_this)
> +{
> + stream_t *p_stream = (stream_t*)p_this;
> + stream_sys_t *p_sys = p_stream->p_sys;
> +
> + msg_Dbg( p_stream, "closing server" );
> + srt_close ( p_sys->sock );
Doesn´t the epoll descriptor also need to be closed?
Also in error paths in Open().
> +}
> +
> +static int Control(stream_t *p_stream, int i_query, va_list args)
> +{
> + VLC_UNUSED (p_stream);
> + bool *pb_bool;
> +
> + switch( i_query )
> + {
> + case STREAM_CAN_SEEK:
> + case STREAM_CAN_FASTSEEK:
> + case STREAM_CAN_PAUSE:
> + case STREAM_CAN_CONTROL_PACE:
> + pb_bool = va_arg( args, bool * );
> + *pb_bool = false;
In new code, we just dereference the result of va_arg() without intermediate
locals.
> + break;
> + default:
> + return VLC_EGENERIC;
GET_DELAY should be added too.
> + }
> + return VLC_SUCCESS;
> +}
> +
> +static block_t *BlockSRT(stream_t *p_stream, bool *restrict eof)
> +{
> + stream_sys_t *p_sys = p_stream->p_sys;
> +
> + block_t *pkt = block_Alloc( p_sys->i_chunk_size );
> +
> + if (unlikely(pkt == NULL))
> + {
> + return NULL;
> + }
> +
> + SRTSOCKET ready[2];
> + if ( srt_epoll_wait( p_sys->i_poll_id, 0, 0, ready, &(int) { 2 }, -1,
> 0, 0, 0, 0 ) == -1 )
> + {
> + msg_Err( p_stream, "%s", srt_getlasterror_str() );
> + goto skip;
> + }
> +
> + int stat = srt_recvmsg( p_sys->sock, (char *)pkt->p_buffer,
> p_sys->i_chunk_size );
> +
> + if ( stat == SRT_ERROR )
> + {
> + msg_Err( p_stream, "%s", srt_getlasterror_str() );
> + goto skip;
> + }
> +
> + pkt->i_buffer = stat;
> + return pkt;
> +
> +skip:
> + *eof = true;
> + block_Release(pkt);
> + return NULL;
> +}
--
雷米‧德尼-库尔蒙
https://www.remlab.net/
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