X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=vss.c;h=0801eeb089b05bf3e0f47aad86d953f5ecc4dee0;hp=704c39300e569d9da65fe2a043880e7966c4f8c2;hb=625c5cd993d07a63061a0788f174e12fa1c221e0;hpb=f41688f647116d0a17513cc86c60cc9729da6502

diff --git a/vss.c b/vss.c
index 704c3930..0801eeb0 100644
--- a/vss.c
+++ b/vss.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1997-2008 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 1997-2009 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -11,34 +11,345 @@
  * senders.
  */
 
-#include <sys/mman.h> /* mmap */
-#include <sys/time.h> /* gettimeofday */
-#include <sys/types.h>
 #include <dirent.h>
 
 #include "para.h"
 #include "error.h"
+#include "portable_io.h"
+#include "fec.h"
 #include "string.h"
 #include "afh.h"
 #include "afs.h"
 #include "server.h"
 #include "net.h"
 #include "server.cmdline.h"
-#include "vss.h"
 #include "list.h"
+#include "vss.h"
 #include "send.h"
 #include "ipc.h"
 #include "fd.h"
-
-static struct timeval announce_tv;
-static struct timeval data_send_barrier;
-static struct timeval eof_barrier;
-static struct timeval autoplay_barrier;
+#include "sched.h"
 
 extern struct misc_meta_data *mmd;
-extern struct sender senders[];
 
-static char *map;
+extern void dccp_send_init(struct sender *);
+extern void http_send_init(struct sender *);
+extern void udp_send_init(struct sender *);
+
+/** The list of supported senders. */
+struct sender senders[] = {
+	{
+		.name = "http",
+		.init = http_send_init,
+	},
+	{
+		.name = "dccp",
+		.init = dccp_send_init,
+	},
+	{
+		.name = "udp",
+		.init = udp_send_init,
+	},
+	{
+		.name = NULL,
+	}
+};
+
+/** The possible states of the afs socket. */
+enum afs_socket_status {
+	/** Socket is inactive. */
+	AFS_SOCKET_READY,
+	/** Socket fd was included in the write fd set for select(). */
+	AFS_SOCKET_CHECK_FOR_WRITE,
+	/** vss wrote a request to the socket and waits for reply from afs. */
+	AFS_SOCKET_AFD_PENDING
+};
+
+/** The task structure for the virtual streaming system. */
+struct vss_task {
+	/** Copied from the -announce_time command line option. */
+	struct timeval announce_tv;
+	/** End of the announcing interval. */
+	struct timeval data_send_barrier;
+	/** End of the EOF interval. */
+	struct timeval eof_barrier;
+	/** Only used if --autoplay_delay was given. */
+	struct timeval autoplay_barrier;
+	/** Used for afs-server communication. */
+	int afs_socket;
+	/** The current state of \a afs_socket. */
+	enum afs_socket_status afsss;
+	/** The memory mapped audio file. */
+	char *map;
+	/** Used by the scheduler. */
+	struct task task;
+	/** Pointer to the header of the mapped audio file. */
+	const char *header_buf;
+	/** Length of the audio file header. */
+	size_t header_len;
+};
+
+static struct list_head fec_client_list;
+
+struct fec_slice {
+	uint8_t num;
+	uint16_t bytes;
+};
+
+struct fec_group {
+	uint32_t num;
+	uint32_t bytes;
+	uint32_t first_chunk;
+	uint32_t num_chunks;
+	struct timeval duration;
+	struct timeval start;
+	struct timeval slice_duration;
+};
+
+struct fec_client {
+	struct fec_client_parms *fcp;
+	struct fec_parms *parms;
+	struct list_head node;
+	struct timeval stream_start;
+	int first_stream_chunk;
+	struct fec_group group;
+	struct fec_slice slice;
+	const unsigned char **src_data;
+	unsigned char *extra_src_buf;
+	size_t extra_src_buf_size;
+	unsigned char *enc_buf;
+	size_t enc_buf_size;
+};
+
+/**
+ * Get the chunk time of the current audio file.
+ *
+ * \return A pointer to a struct containing the chunk time, or NULL,
+ * if currently no audio file is selected.
+ */
+struct timeval *vss_chunk_time(void)
+{
+	if (mmd->afd.afhi.chunk_tv.tv_sec == 0 &&
+			mmd->afd.afhi.chunk_tv.tv_usec == 0)
+		return NULL;
+	return &mmd->afd.afhi.chunk_tv;
+}
+
+static void setup_fec_group(struct fec_client *fc, struct vss_task *vsst)
+{
+	uint32_t num_bytes = 0, chunk_num, max_group_size, last_payload_size;
+	int i, k = fc->fcp->data_slices_per_group;
+	const unsigned char *start_buf = NULL;
+	struct timeval tmp, *chunk_tv = vss_chunk_time();
+
+	assert(chunk_tv);
+	max_group_size = (fc->fcp->max_slice_bytes - FEC_HEADER_SIZE) * k;
+	chunk_num = fc->group.first_chunk;
+	for (;;) {
+		const unsigned char *buf;
+		size_t len;
+
+		if (chunk_num >= mmd->afd.afhi.chunks_total)
+			break;
+		afh_get_chunk(chunk_num, &mmd->afd.afhi, vsst->map, (const char **)&buf, &len);
+		if (!start_buf)
+			start_buf = buf;
+		if (num_bytes + len > max_group_size)
+			break;
+		chunk_num++;
+		num_bytes += len;
+	}
+	assert(start_buf);
+	fc->group.num_chunks = chunk_num - fc->group.first_chunk;
+	fc->group.num++;
+	fc->group.bytes = num_bytes;
+	fc->slice.num = 0;
+	fc->slice.bytes = ROUND_UP(num_bytes, k) / k;
+
+	/* The last slice will not be fully used */
+	last_payload_size = num_bytes % fc->slice.bytes;
+	if (!last_payload_size)
+		last_payload_size = fc->slice.bytes;
+
+	tv_scale(fc->group.num_chunks, chunk_tv, &fc->group.duration);
+	tv_scale(fc->group.first_chunk - fc->first_stream_chunk, chunk_tv,
+		&tmp);
+	tv_add(&fc->stream_start, &tmp, &fc->group.start);
+	tv_divide(fc->fcp->slices_per_group, &fc->group.duration,
+		&fc->group.slice_duration);
+
+	for (i = 0; i < k; i++)
+		fc->src_data[i] = start_buf + i * fc->slice.bytes;
+
+	if ((char *)start_buf + k * fc->slice.bytes > vsst->map + mmd->size) {
+		/* can not use last slice as it goes beyond the map */
+		if (fc->extra_src_buf_size < fc->slice.bytes)
+			fc->extra_src_buf = para_realloc(fc->extra_src_buf, fc->slice.bytes);
+		memcpy(fc->extra_src_buf, start_buf + (k - 1) * fc->slice.bytes,
+			last_payload_size);
+		memset(fc->extra_src_buf + last_payload_size, 0,
+			fc->slice.bytes - last_payload_size);
+		fc->src_data[k - 1] = fc->extra_src_buf;
+	}
+
+}
+
+/**
+ * Write a fec header to a buffer.
+ *
+ * \param buf The buffer to write to.
+ * \param h The fec header to write.
+ */
+static void write_fec_header(struct fec_client *fc)
+{
+	char *buf = (char *)fc->enc_buf;
+
+	write_u32(buf, FEC_MAGIC);
+
+	write_u8(buf + 4, fc->fcp->slices_per_group);
+	write_u8(buf + 5, fc->fcp->data_slices_per_group);
+	write_u32(buf + 6, (uint32_t)0); /* audio header len */
+
+	write_u32(buf + 10, fc->group.num);
+	write_u32(buf + 14, fc->group.bytes);
+
+	write_u8(buf + 18, fc->slice.num);
+	write_u16(buf + 20, fc->slice.bytes);
+	memset(buf + 22, 0, 11);
+}
+
+/**
+ * Return a buffer that marks the end of the stream.
+ *
+ * \return The length of the eof buffer.
+ *
+ * This is used for (multicast) udp streaming where closing the socket on the
+ * sender might not give rise to an eof condition at the peer.
+ */
+size_t vss_get_fec_eof_packet(const char **buf)
+{
+	static const char fec_eof_packet[FEC_HEADER_SIZE] =
+	"\xec\x0d\xcc\xfe\0\0\0\0"
+	"\0\0\0\0\0\0\0\0"
+	"\0\0\0\0\0\0\0\0"
+	"\0\0\0\0\0\0\0\0";
+	*buf = fec_eof_packet;
+	return FEC_HEADER_SIZE;
+}
+
+static void compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
+{
+	if (fc->first_stream_chunk < 0) {
+		fc->stream_start = *now;
+		fc->first_stream_chunk = mmd->current_chunk;
+		fc->group.first_chunk = mmd->current_chunk;
+		fc->group.num = 0;
+		setup_fec_group(fc, vsst);
+	} else if (fc->slice.num == fc->fcp->slices_per_group) {
+		fc->group.first_chunk += fc->group.num_chunks;
+		setup_fec_group(fc, vsst);
+
+	}
+	if (fc->enc_buf_size < fc->slice.bytes + FEC_HEADER_SIZE) {
+		fc->enc_buf_size = fc->slice.bytes + FEC_HEADER_SIZE;
+		fc->enc_buf = para_realloc(fc->enc_buf, fc->enc_buf_size);
+	}
+	write_fec_header(fc);
+	fec_encode(fc->parms, fc->src_data, fc->enc_buf + FEC_HEADER_SIZE,
+		fc->slice.num, fc->slice.bytes);
+}
+
+/**
+ * Add one entry to the list of active fec clients.
+ *
+ * \param fcp Describes the fec parameters to be used for this client.
+ * \param result An opaque pointer that must be used by remove the client later.
+ *
+ * \return Standard.
+ */
+int vss_add_fec_client(struct fec_client_parms *fcp, struct fec_client **result)
+{
+	int ret;
+	struct fec_client *fc;
+
+	if (fcp->max_slice_bytes < FEC_HEADER_SIZE + fcp->data_slices_per_group)
+		return -ERRNO_TO_PARA_ERROR(EINVAL);
+	fc = para_calloc(sizeof(*fc));
+	fc->fcp = fcp;
+	ret = fec_new(fcp->data_slices_per_group, fcp->slices_per_group,
+		&fc->parms);
+	if (ret < 0)
+		goto err;
+	fc->first_stream_chunk = -1; /* stream not yet started */
+	fc->src_data = para_malloc(fc->fcp->slices_per_group * sizeof(char *));
+	para_list_add(&fc->node, &fec_client_list);
+	*result = fc;
+	return 1;
+err:
+	fec_free(fc->parms);
+	free(fc);
+	*result = NULL;
+	return ret;
+}
+
+/**
+ * Remove one entry from the list of active fec clients.
+ *
+ * \param result The client to be removed.
+ */
+void vss_del_fec_client(struct fec_client *fc)
+{
+	list_del(&fc->node);
+	free(fc->src_data);
+	free(fc->enc_buf);
+	free(fc->extra_src_buf);
+	fec_free(fc->parms);
+	free(fc);
+}
+
+/*
+ * Compute if/when next slice is due. If it isn't due yet and \a diff is
+ * not \p Null, compute the time difference next - now, where
+ *
+ *	next = stream_start + (first_group_chunk - first_stream_chunk)
+ *		* chunk_time + slice_num * slice_time
+ */
+static int next_slice_is_due(struct fec_client *fc, struct timeval *diff)
+{
+	struct timeval tmp, next;
+	int ret;
+
+	if (fc->first_stream_chunk < 0)
+		return 1;
+	tv_scale(fc->slice.num, &fc->group.slice_duration, &tmp);
+	tv_add(&tmp, &fc->group.start, &next);
+	ret = tv_diff(&next, now, diff);
+	return ret < 0? 1 : 0;
+}
+
+static void compute_slice_timeout(struct timeval *timeout)
+{
+	struct fec_client *fc;
+
+	assert(vss_playing());
+	list_for_each_entry(fc, &fec_client_list, node) {
+		struct timeval diff;
+		int ret = next_slice_is_due(fc, &diff);
+
+		// PARA_NOTICE_LOG("diff: %lu, ret: %d\n", tv2ms(&diff), ret);
+		if (ret) {
+			timeout->tv_sec = 0;
+			timeout->tv_usec = 0;
+			goto out;
+		}
+		/* timeout = min(timeout, diff) */
+		if (tv_diff(&diff, timeout, NULL) < 0)
+			*timeout = diff;
+	}
+out:
+	return;
+	PARA_NOTICE_LOG("slice timeout: %lu:%lu\n", (long unsigned)timeout->tv_sec, (long unsigned)timeout->tv_usec);
+}
 
 /**
  * Check if vss status flag \a P (playing) is set.
@@ -97,60 +408,8 @@ unsigned int vss_stopped(void)
 		&& !(mmd->new_vss_status_flags & VSS_PLAYING);
 }
 
-/**
- * Get the data of the given chunk.
- *
- * \param chunk_num The number of the desired chunk.
- * \param buf Chunk data.
- * \param len Chunk length in bytes.
- *
- * \return Standard.
- */
-int vss_get_chunk(long unsigned chunk_num, char **buf, size_t *len)
-{
-	if (!map || !vss_playing())
-		return -E_CHUNK;
-	if (chunk_num >= mmd->afd.afhi.chunks_total)
-		return -E_CHUNK;
-	afh_get_chunk(chunk_num, &mmd->afd.afhi, map, buf, len);
-	return 1;
-}
-
-/**
- * Initialize the virtual streaming system.
- *
- * This also initializes all supported senders and starts streaming
- * if the --autoplay command line flag was given.
- */
-void vss_init(void)
-{
-	int i;
-	char *hn = para_hostname(), *home = para_homedir();
-	long unsigned announce_time = conf.announce_time_arg > 0?
-			conf.announce_time_arg : 300,
-		autoplay_delay = conf.autoplay_delay_arg > 0?
-			conf.autoplay_delay_arg : 0;
-	ms2tv(announce_time, &announce_tv);
-	PARA_INFO_LOG("announce timeval: %lums\n", tv2ms(&announce_tv));
-	for (i = 0; senders[i].name; i++) {
-		PARA_NOTICE_LOG("initializing %s sender\n", senders[i].name);
-		senders[i].init(&senders[i]);
-	}
-	free(hn);
-	free(home);
-	if (conf.autoplay_given) {
-		struct timeval now, tmp;
-		mmd->vss_status_flags |= VSS_PLAYING;
-		mmd->new_vss_status_flags |= VSS_PLAYING;
-		gettimeofday(&now, NULL);
-		ms2tv(autoplay_delay, &tmp);
-		tv_add(&now, &tmp, &autoplay_barrier);
-	}
-}
-
-static int chk_barrier(const char *bname, const struct timeval *now,
-		const struct timeval *barrier, struct timeval *diff,
-		int print_log)
+static int chk_barrier(const char *bname, const struct timeval *barrier,
+		struct timeval *diff, int print_log)
 {
 	long ms;
 
@@ -166,78 +425,67 @@ static int chk_barrier(const char *bname, const struct timeval *now,
  * != NULL: timeout for next chunk
  * NULL: nothing to do
  */
-static struct timeval *vss_compute_timeout(void)
+static struct timeval *vss_compute_timeout(struct vss_task *vsst)
 {
 	static struct timeval the_timeout;
-	struct timeval now, next_chunk;
+	struct timeval next_chunk;
 
-	if (vss_next() && map) {
+	if (vss_next() && vsst->map) {
 		/* only sleep a bit, nec*/
 		the_timeout.tv_sec = 0;
 		the_timeout.tv_usec = 100;
 		return &the_timeout;
 	}
-	gettimeofday(&now, NULL);
-	if (chk_barrier("autoplay_delay", &now, &autoplay_barrier,
+	if (chk_barrier("autoplay_delay", &vsst->autoplay_barrier,
 			&the_timeout, 1) < 0)
 		return &the_timeout;
-	if (chk_barrier("eof", &now, &eof_barrier, &the_timeout, 1) < 0)
+	if (chk_barrier("eof", &vsst->eof_barrier, &the_timeout, 1) < 0)
 		return &the_timeout;
-	if (chk_barrier("data send", &now, &data_send_barrier,
+	if (chk_barrier("data send", &vsst->data_send_barrier,
 			&the_timeout, 1) < 0)
 		return &the_timeout;
-	if (!vss_playing() || !map)
+	if (!vss_playing() || !vsst->map)
 		return NULL;
 	compute_chunk_time(mmd->chunks_sent, &mmd->afd.afhi.chunk_tv,
 		&mmd->stream_start, &next_chunk);
-	if (chk_barrier("chunk", &now, &next_chunk, &the_timeout, 0) < 0)
+	if (chk_barrier("chunk", &next_chunk, &the_timeout, 0) >= 0) {
+		/* chunk is due or bof */
+		the_timeout.tv_sec = 0;
+		the_timeout.tv_usec = 0;
 		return &the_timeout;
-	/* chunk is due or bof */
-	the_timeout.tv_sec = 0;
-	the_timeout.tv_usec = 0;
+	}
+	/* compute min of current timeout and next slice time */
+	compute_slice_timeout(&the_timeout);
 	return &the_timeout;
 }
 
-static void vss_eof(void)
+static void vss_eof(struct vss_task *vsst)
 {
-	struct timeval now;
-	char *tmp;
 
+	mmd->stream_start = *now;
+	if (!vsst->map)
+		return;
 	if (mmd->new_vss_status_flags & VSS_NOMORE)
 		mmd->new_vss_status_flags = VSS_NEXT;
-	gettimeofday(&now, NULL);
-	tv_add(&mmd->afd.afhi.eof_tv, &now, &eof_barrier);
-	munmap(map, mmd->size);
-	map = NULL;
+	tv_add(&mmd->afd.afhi.eof_tv, now, &vsst->eof_barrier);
+	para_munmap(vsst->map, mmd->size);
+	vsst->map = NULL;
 	mmd->chunks_sent = 0;
 	mmd->offset = 0;
 	mmd->afd.afhi.seconds_total = 0;
+	mmd->afd.afhi.chunk_tv.tv_sec = 0;
+	mmd->afd.afhi.chunk_tv.tv_usec = 0;
 	free(mmd->afd.afhi.chunk_table);
 	mmd->afd.afhi.chunk_table = NULL;
-	tmp  = make_message("%s:\n%s:\n%s:\n", status_item_list[SI_AUDIO_FILE_INFO],
+	free(mmd->afd.afhi.info_string);
+	mmd->afd.afhi.info_string = make_message("%s:\n%s:\n%s:\n", status_item_list[SI_AUDIO_FILE_INFO],
 		status_item_list[SI_TAGINFO1], status_item_list[SI_TAGINFO2]);
-	strncpy(mmd->afd.afhi.info_string, tmp, sizeof(mmd->afd.afhi.info_string));
-	mmd->afd.afhi.info_string[sizeof(mmd->afd.afhi.info_string) - 1] = '\0';
 	make_empty_status_items(mmd->afd.verbose_ls_output);
-	free(tmp);
 	mmd->mtime = 0;
 	mmd->size = 0;
 	mmd->events++;
 }
 
-/**
- * Get the header of the current audio file.
- *
- * \param buf The length of the header is stored here.
- * \param len Points to a buffer containing the header on return.
- *
- * \sa afh_get_header.
- */
-void vss_get_header(char **buf, size_t *len)
-{
-	afh_get_header(&mmd->afd.afhi, map, buf, len);
-}
-
 /**
  * Get the list of all supported audio formats.
  *
@@ -250,53 +498,34 @@ const char *supported_audio_formats(void)
 	return SUPPORTED_AUDIO_FORMATS;
 }
 
-/**
- * Get the chunk time of the current audio file.
- *
- * \return A pointer to a struct containing the chunk time, or NULL,
- * if currently no audio file is selected.
- */
-struct timeval *vss_chunk_time(void)
+static int need_to_request_new_audio_file(struct vss_task *vsst)
 {
-	if (!map)
-		return NULL;
-	return &mmd->afd.afhi.chunk_tv;
-}
+	struct timeval diff;
 
-/** The possible states of the afs socket. See \ref afs_socket. */
-enum afs_socket_status {
-	/** Socket is inactive. */
-	AFS_SOCKET_READY,
-	/** Socket fd was included in the write fd set for select(). */
-	AFS_SOCKET_CHECK_FOR_WRITE,
-	/** vss wrote a request to the socket and waits for afs to reply. */
-	AFS_SOCKET_AFD_PENDING
-};
-
-static enum afs_socket_status afsss;
-
-static int need_to_request_new_audio_file(void)
-{
-	if (map) /* have audio file */
+	if (vsst->map) /* have audio file */
 		return 0;
 	if (!vss_playing()) /* don't need one */
 		return 0;
 	if (mmd->new_vss_status_flags & VSS_NOMORE)
 		return 0;
-	if (afsss == AFS_SOCKET_AFD_PENDING) /* already requested one */
+	if (vsst->afsss == AFS_SOCKET_AFD_PENDING) /* already requested one */
+		return 0;
+	if (chk_barrier("autoplay_delay", &vsst->autoplay_barrier,
+			&diff, 1) < 0)
 		return 0;
 	return 1;
 }
 
+
+
 /**
  * Compute the timeout for para_server's main select-loop.
  *
  * This function gets called from para_server to determine the timeout value
  * for its main select loop.
  *
- * \param rfds The set of file descriptors to be checked for reading.
- * \param wfds The set of file descriptors to be checked for writing.
- * \param max_fileno The highest-numbered file descriptor.
+ * \param s Pointer to the server scheduler.
+ * \param t Pointer to the vss task structure.
  *
  * Before the timeout is computed, the current vss status flags are evaluated
  * and acted upon by calling appropriate functions from the lower layers.
@@ -305,50 +534,51 @@ static int need_to_request_new_audio_file(void)
  * 	- request a new audio file from afs,
  *	- shutdown of all senders (stop/pause command),
  *	- reposition the stream (ff/jmp command).
- *
- * \return A pointer to a struct timeval containing the timeout for the next
- * chunk of data to be sent, or NULL if we're not sending right now.
  */
-struct timeval *vss_preselect(fd_set *rfds, fd_set *wfds, int *max_fileno)
+static void vss_pre_select(struct sched *s, struct task *t)
 {
 	int i;
-	struct timeval now;
+	struct timeval *tv, diff;
+	struct vss_task *vsst = container_of(t, struct vss_task, task);
 
-	if (!map || vss_next() || vss_paused() || vss_repos())
+	if (!vsst->map || vss_next() || vss_paused() || vss_repos()) {
+		struct fec_client *fc, *tmp;
 		for (i = 0; senders[i].name; i++)
-			senders[i].shutdown_clients();
+			if (senders[i].shutdown_clients)
+				senders[i].shutdown_clients();
+		list_for_each_entry_safe(fc, tmp, &fec_client_list, node)
+			fc->first_stream_chunk = -1;
+	}
 	if (vss_next())
-		vss_eof();
+		vss_eof(vsst);
 	else if (vss_paused()) {
-		if (mmd->chunks_sent) {
-			gettimeofday(&now, NULL);
-			tv_add(&mmd->afd.afhi.eof_tv, &now, &eof_barrier);
-		}
+		if (mmd->chunks_sent)
+			tv_add(&mmd->afd.afhi.eof_tv, now, &vsst->eof_barrier);
 		mmd->chunks_sent = 0;
 	} else if (vss_repos()) {
-		gettimeofday(&now, NULL);
-		tv_add(&now, &announce_tv, &data_send_barrier);
-		tv_add(&mmd->afd.afhi.eof_tv, &now, &eof_barrier);
+		tv_add(now, &vsst->announce_tv, &vsst->data_send_barrier);
+		tv_add(&mmd->afd.afhi.eof_tv, now, &vsst->eof_barrier);
 		mmd->chunks_sent = 0;
 		mmd->current_chunk = mmd->repos_request;
 		mmd->new_vss_status_flags &= ~VSS_REPOS;
 	}
-
-	if (need_to_request_new_audio_file()) {
+	if (need_to_request_new_audio_file(vsst)) {
 		PARA_DEBUG_LOG("ready and playing, but no audio file\n");
-		para_fd_set(afs_socket, wfds, max_fileno);
-		afsss = AFS_SOCKET_CHECK_FOR_WRITE;
+		para_fd_set(vsst->afs_socket, &s->wfds, &s->max_fileno);
+		vsst->afsss = AFS_SOCKET_CHECK_FOR_WRITE;
 	} else
-		para_fd_set(afs_socket, rfds, max_fileno);
+		para_fd_set(vsst->afs_socket, &s->rfds, &s->max_fileno);
 	for (i = 0; senders[i].name; i++) {
 		if (!senders[i].pre_select)
 			continue;
-		senders[i].pre_select(max_fileno, rfds, wfds);
+		senders[i].pre_select(&s->max_fileno, &s->rfds, &s->wfds);
 	}
-	return vss_compute_timeout();
+	tv = vss_compute_timeout(vsst);
+	if (tv && tv_diff(tv, &s->timeout, &diff) < 0)
+		s->timeout = *tv;
 }
 
-static int recv_afs_msg(int *fd, uint32_t *code, uint32_t *data)
+static int recv_afs_msg(int afs_socket, int *fd, uint32_t *code, uint32_t *data)
 {
 	char control[255], buf[8];
 	struct msghdr msg = {.msg_iov = NULL};
@@ -367,7 +597,6 @@ static int recv_afs_msg(int *fd, uint32_t *code, uint32_t *data)
 	ret = recvmsg(afs_socket, &msg, 0);
 	if (ret < 0)
 		return -ERRNO_TO_PARA_ERROR(errno);
-	afsss = AFS_SOCKET_READY;
 	if (iov.iov_len != sizeof(buf))
 		return -E_AFS_SHORT_READ;
 	*code = *(uint32_t*)buf;
@@ -383,15 +612,15 @@ static int recv_afs_msg(int *fd, uint32_t *code, uint32_t *data)
 	return 1;
 }
 
-static void recv_afs_result(void)
+static void recv_afs_result(struct vss_task *vsst)
 {
 	int ret, passed_fd, shmid;
 	uint32_t afs_code = 0, afs_data = 0;
 	struct stat statbuf;
-	struct timeval now;
 
+	vsst->afsss = AFS_SOCKET_READY;
 	mmd->afd.afhi.chunk_table = NULL;
-	ret = recv_afs_msg(&passed_fd, &afs_code, &afs_data);
+	ret = recv_afs_msg(vsst->afs_socket, &passed_fd, &afs_code, &afs_data);
 	if (ret < 0)
 		goto err;
 	PARA_DEBUG_LOG("fd: %d, code: %u, shmid: %u\n", passed_fd, afs_code,
@@ -414,8 +643,10 @@ static void recv_afs_result(void)
 	}
 	mmd->size = statbuf.st_size;
 	mmd->mtime = statbuf.st_mtime;
-	map = para_mmap(mmd->size, PROT_READ, MAP_PRIVATE,
-		passed_fd, 0);
+	ret = para_mmap(mmd->size, PROT_READ, MAP_PRIVATE, passed_fd,
+		0, &vsst->map);
+	if (ret < 0)
+		goto err;
 	close(passed_fd);
 	mmd->chunks_sent = 0;
 	mmd->current_chunk = 0;
@@ -423,8 +654,8 @@ static void recv_afs_result(void)
 	mmd->events++;
 	mmd->num_played++;
 	mmd->new_vss_status_flags &= (~VSS_NEXT);
-	gettimeofday(&now, NULL);
-	tv_add(&now, &announce_tv, &data_send_barrier);
+	afh_get_header(&mmd->afd.afhi, vsst->map, &vsst->header_buf,
+		&vsst->header_len);
 	return;
 err:
 	free(mmd->afd.afhi.chunk_table);
@@ -437,79 +668,143 @@ err:
 /**
  * Main sending function.
  *
- * This function gets called from para_server as soon as the next chunk of data
- * should be pushed out. It obtains a pointer to the data to be sent out as
- * well as its length from mmd->afd.afhi. This information is then passed to
- * each supported sender's send() function which is supposed to send out the data
- * to all connected clients.
+ * This function gets called from vss_post_select(). It checks whether the next
+ * chunk of data should be pushed out. It obtains a pointer to the data to be
+ * sent out as well as its length from mmd->afd.afhi. This information is then
+ * passed to each supported sender's send() function as well as to the send()
+ * functions of each registered fec client.
  */
-static void vss_send_chunk(void)
+static void vss_send(struct vss_task *vsst)
 {
 	int i;
-	struct timeval now, due;
-	char *buf;
-	size_t len;
+	struct timeval due;
+	struct fec_client *fc, *tmp_fc;
 
-	if (!map || !vss_playing())
+	if (!vsst->map || !vss_playing())
 		return;
-	gettimeofday(&now, NULL);
-	compute_chunk_time(mmd->chunks_sent, &mmd->afd.afhi.chunk_tv,
-		&mmd->stream_start, &due);
-	if (tv_diff(&due, &now, NULL) > 0)
+	if (chk_barrier("eof", &vsst->eof_barrier, &due, 1) < 0)
 		return;
-	if (chk_barrier("eof", &now, &eof_barrier, &due, 1) < 0)
-		return;
-	if (chk_barrier("data send", &now, &data_send_barrier,
+	if (chk_barrier("data send", &vsst->data_send_barrier,
 			&due, 1) < 0)
 		return;
-	mmd->new_vss_status_flags &= ~VSS_REPOS;
 	if (mmd->current_chunk >= mmd->afd.afhi.chunks_total) { /* eof */
 		mmd->new_vss_status_flags |= VSS_NEXT;
 		return;
 	}
-	/*
-	 * We call the send function also in case of empty chunks as they
-	 * might have still some data queued which can be sent in this case.
-	 */
 	if (!mmd->chunks_sent) {
 		struct timeval tmp;
-		gettimeofday(&mmd->stream_start, NULL);
+		mmd->stream_start = *now;
 		tv_scale(mmd->current_chunk, &mmd->afd.afhi.chunk_tv, &tmp);
 		mmd->offset = tv2ms(&tmp);
 		mmd->events++;
 	}
-	afh_get_chunk(mmd->current_chunk, &mmd->afd.afhi, map, &buf, &len);
-	for (i = 0; senders[i].name; i++)
-		senders[i].send(mmd->current_chunk, mmd->chunks_sent, buf, len);
+	compute_chunk_time(mmd->chunks_sent, &mmd->afd.afhi.chunk_tv,
+		&mmd->stream_start, &due);
+	if (tv_diff(&due, now, NULL) <= 0) {
+		const char *buf;
+		size_t len;
+		/*
+		 * We call the send function also in case of empty chunks as
+		 * they might have still some data queued which can be sent in
+		 * this case.
+		 */
+		afh_get_chunk(mmd->current_chunk, &mmd->afd.afhi, vsst->map,
+			&buf, &len);
+		for (i = 0; senders[i].name; i++) {
+			if (!senders[i].send)
+				continue;
+			senders[i].send(mmd->current_chunk, mmd->chunks_sent,
+				buf, len, vsst->header_buf, vsst->header_len);
+		}
+	}
+	list_for_each_entry_safe(fc, tmp_fc, &fec_client_list, node) {
+		if (!next_slice_is_due(fc, NULL))
+			continue;
+		compute_next_fec_slice(fc, vsst);
+		PARA_DEBUG_LOG("sending %d:%d (%zu bytes)\n", fc->group.num,
+			fc->slice.num, fc->slice.bytes);
+		fc->fcp->send((char *)fc->enc_buf,
+			fc->slice.bytes + FEC_HEADER_SIZE,
+			fc->fcp->private_data);
+		fc->slice.num++;
+	}
 	mmd->new_vss_status_flags |= VSS_PLAYING;
 	mmd->chunks_sent++;
 	mmd->current_chunk++;
 }
 
-void vss_post_select(fd_set *rfds, fd_set *wfds)
+static void vss_post_select(struct sched *s, struct task *t)
 {
 	int ret, i;
+	struct vss_task *vsst = container_of(t, struct vss_task, task);
 
 	if (mmd->sender_cmd_data.cmd_num >= 0) {
 		int num = mmd->sender_cmd_data.cmd_num,
-			s = mmd->sender_cmd_data.sender_num;
+			sender_num = mmd->sender_cmd_data.sender_num;
 
-		if (senders[s].client_cmds[num])
-			senders[s].client_cmds[num](&mmd->sender_cmd_data);
+		if (senders[sender_num].client_cmds[num])
+			senders[sender_num].client_cmds[num](&mmd->sender_cmd_data);
 		mmd->sender_cmd_data.cmd_num = -1;
 	}
-	if (afsss != AFS_SOCKET_CHECK_FOR_WRITE) {
-		if (FD_ISSET(afs_socket, rfds))
-			recv_afs_result();
-	} else if (FD_ISSET(afs_socket, wfds)) {
+	if (vsst->afsss != AFS_SOCKET_CHECK_FOR_WRITE) {
+		if (FD_ISSET(vsst->afs_socket, &s->rfds))
+			recv_afs_result(vsst);
+	} else if (FD_ISSET(vsst->afs_socket, &s->wfds)) {
 		PARA_NOTICE_LOG("requesting new fd from afs\n");
-		ret = send_buffer(afs_socket, "new");
-		afsss = AFS_SOCKET_AFD_PENDING;
+		ret = send_buffer(vsst->afs_socket, "new");
+		vsst->afsss = AFS_SOCKET_AFD_PENDING;
 	}
 	for (i = 0; senders[i].name; i++) {
 		if (!senders[i].post_select)
 			continue;
-		senders[i].post_select(rfds, wfds);
+		senders[i].post_select(&s->rfds, &s->wfds);
+	}
+	if ((vss_playing() && !(mmd->vss_status_flags & VSS_PLAYING)) ||
+			(vss_next() && vss_playing()))
+		tv_add(now, &vsst->announce_tv, &vsst->data_send_barrier);
+	vss_send(vsst);
+}
+
+/**
+ * Initialize the virtual streaming system task.
+ *
+ * \param afs_socket The fd for communication with afs.
+ *
+ * This also initializes all supported senders and starts streaming
+ * if the --autoplay command line flag was given.
+ */
+void init_vss_task(int afs_socket)
+{
+	static struct vss_task vss_task_struct, *vsst = &vss_task_struct;
+	int i;
+	char *hn = para_hostname(), *home = para_homedir();
+	long unsigned announce_time = conf.announce_time_arg > 0?
+			conf.announce_time_arg : 300,
+		autoplay_delay = conf.autoplay_delay_arg > 0?
+			conf.autoplay_delay_arg : 0;
+
+	vsst->afs_socket = afs_socket;
+	vsst->task.pre_select = vss_pre_select;
+	vsst->task.post_select = vss_post_select;
+	ms2tv(announce_time, &vsst->announce_tv);
+	PARA_INFO_LOG("announce timeval: %lums\n", tv2ms(&vsst->announce_tv));
+	for (i = 0; senders[i].name; i++) {
+		PARA_NOTICE_LOG("initializing %s sender\n", senders[i].name);
+		senders[i].init(&senders[i]);
+	}
+	free(hn);
+	free(home);
+	mmd->sender_cmd_data.cmd_num = -1;
+	make_empty_status_items(mmd->afd.verbose_ls_output);
+	if (conf.autoplay_given) {
+		struct timeval tmp;
+		mmd->vss_status_flags |= VSS_PLAYING;
+		mmd->new_vss_status_flags |= VSS_PLAYING;
+		ms2tv(autoplay_delay, &tmp);
+		tv_add(now, &tmp, &vsst->autoplay_barrier);
+		tv_add(&vsst->autoplay_barrier, &vsst->announce_tv,
+			&vsst->data_send_barrier);
 	}
-	vss_send_chunk();
+	INIT_LIST_HEAD(&fec_client_list);
+	register_task(&vsst->task);
 }