X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=vss.c;h=aae601d14153d6973a8a86f8f8a93e69cd6c8bbd;hp=0bc2aed48ab3a01e0224946ff689c0268c976a2c;hb=ddd7cd853044105f329a2c70cce2d8f1470f559e;hpb=9be5a49b2b24d49de40f87f9aba3378dd04a7b0e

diff --git a/vss.c b/vss.c
index 0bc2aed4..aae601d1 100644
--- a/vss.c
+++ b/vss.c
@@ -1,52 +1,525 @@
 /*
- * Copyright (C) 1997-2007 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 1997-2009 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
 
-/** \file vss.c the virtual streaming system
+/** \file vss.c The virtual streaming system.
  *
  * This contains the audio streaming code of para_server which is independent
  * of the current audio format, audio file selector and of the activated
  * 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 "afs_common.h"
+#include "list.h"
 #include "vss.h"
 #include "send.h"
 #include "ipc.h"
 #include "fd.h"
+#include "sched.h"
 
-extern const char *status_item_list[];
+extern struct misc_meta_data *mmd;
 
-static struct timeval announce_tv;
-static struct timeval data_send_barrier;
-static struct timeval eof_barrier;
-static struct timeval autoplay_barrier;
+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,
+	}
+};
 
-extern struct misc_meta_data *mmd;
-extern struct sender senders[];
+/** 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;
+	/** Time between audio file headers are sent. */
+	struct timeval header_interval;
+};
+
+/**
+ * The list of currently connected fec clients.
+ *
+ * Senders may use \ref vss_add_fec_client() to add entries to the list.
+ */
+static struct list_head fec_client_list;
+
+/**
+ * Data associated with one FEC group.
+ *
+ * A FEC group consists of a fixed number of slices and this number is given by
+ * the \a slices_per_group parameter of struct \ref fec_client_parms. Each FEC
+ * group contains a number of chunks of the current audio file.
+ *
+ * FEC slices directly correspond to the data packages sent by the paraslash
+ * senders that use FEC. Each slice is identified by its group number and its
+ * number within the group. All slices have the same size, but the last slice
+ * of the group may not be filled entirely.
+ */
+struct fec_group {
+	/** The number of the FEC group. */
+	uint32_t num;
+	/** Number of bytes in this group. */
+	uint32_t bytes;
+	/** The first chunk of the current audio file belonging to the group. */
+	uint32_t first_chunk;
+	/** The number of chunks contained in this group. */
+	uint32_t num_chunks;
+	/** When the first chunk was sent. */
+	struct timeval start;
+	/** The group duration divided by the number of slices. */
+	struct timeval slice_duration;
+	/** Group contains the audio file header that occupies that many slices. */
+	uint8_t num_header_slices;
+};
+
+/**
+ * Describes one connected FEC client.
+ */
+struct fec_client {
+	/** If negative, this client is temporarily disabled. */
+	int error;
+	/** Parameters requested by the client. */
+	struct fec_client_parms *fcp;
+	/** Used by the core FEC code. */
+	struct fec_parms *parms;
+	/** The position of this client in the fec client list. */
+	struct list_head node;
+	/** When the first slice for this client was sent. */
+	struct timeval stream_start;
+	/** The first chunk sent to this FEC client. */
+	int first_stream_chunk;
+	/** Describes the current group. */
+	struct fec_group group;
+	/** The current slice. */
+	uint8_t current_slice_num;
+	/** The data to be FEC-encoded (point to a region within the mapped audio file). */
+	const unsigned char **src_data;
+	/** Last time an audio  header was sent. */
+	struct timeval next_header_time;
+	/** Used for the last source pointer of an audio file. */
+	unsigned char *extra_src_buf;
+	/** Extra slices needed to store largest chunk + header. */
+	int num_extra_slices;
+	/** Contains the FEC-encoded data. */
+	unsigned char *enc_buf;
+};
+
+/**
+ * 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;
+}
+
+/**
+ * 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, struct vss_task *vsst)
+{
+	char *buf = (char *)fc->enc_buf;
+	struct fec_group *g = &fc->group;
+	struct fec_client_parms *p = fc->fcp;
+
+	write_u32(buf, FEC_MAGIC);
+
+	write_u8(buf + 4, p->slices_per_group + fc->num_extra_slices);
+	write_u8(buf + 5, p->data_slices_per_group + fc->num_extra_slices);
+	write_u32(buf + 6, g->num_header_slices? vsst->header_len : 0);
+
+	write_u32(buf + 10, g->num);
+	write_u32(buf + 14, g->bytes);
+
+	write_u8(buf + 18, fc->current_slice_num);
+	write_u16(buf + 20, p->max_slice_bytes - FEC_HEADER_SIZE);
+	write_u8(buf + 22, g->first_chunk? 0 : 1);
+	write_u8(buf + 23, vsst->header_len? 1 : 0);
+	memset(buf + 24, 0, 7);
+}
+
+static int need_audio_header(struct fec_client *fc, struct vss_task *vsst)
+{
+	if (!mmd->current_chunk) {
+		tv_add(now, &vsst->header_interval, &fc->next_header_time);
+		return 0;
+	}
+	if (!vsst->header_buf)
+		return 0;
+	if (!vsst->header_len)
+		return 0;
+	if (fc->group.num && tv_diff(&fc->next_header_time, now, NULL) > 0)
+		return 0;
+	tv_add(now, &vsst->header_interval, &fc->next_header_time);
+	return 1;
+}
+
+static int num_slices(long unsigned bytes, struct fec_client *fc, uint8_t *result)
+{
+	unsigned long m = fc->fcp->max_slice_bytes - FEC_HEADER_SIZE;
+	unsigned rv, redundant_slices = fc->fcp->slices_per_group
+		- fc->fcp->data_slices_per_group;
+
+	if (!m)
+		return -E_BAD_CT;
+	rv = (bytes + m - 1) / m;
+	if (rv + redundant_slices > 255)
+		return -E_BAD_CT;
+	*result = rv;
+	return 1;
+}
+
+static void set_slice_duration(struct fec_client *fc, struct fec_group *g)
+{
+	struct timeval group_duration, *chunk_tv = vss_chunk_time();
+
+	tv_scale(g->num_chunks, chunk_tv, &group_duration);
+	tv_divide(fc->fcp->slices_per_group + fc->num_extra_slices,
+		&group_duration, &g->slice_duration);
+	PARA_DEBUG_LOG("durations (group/chunk/slice): %lu/%lu/%lu\n",
+		tv2ms(&group_duration), tv2ms(chunk_tv), tv2ms(&g->slice_duration));
+}
+
+static int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
+{
+	int ret, i, k, data_slices;
+	size_t len;
+	const char *buf, *start_buf;
+	struct timeval tmp, *chunk_tv = vss_chunk_time();
+	struct fec_group *g = &fc->group;
+	unsigned slice_bytes = fc->fcp->max_slice_bytes - FEC_HEADER_SIZE;
+	uint32_t max_data_size;
+
+	assert(chunk_tv);
+	k = fc->fcp->data_slices_per_group + fc->num_extra_slices;
+	if (fc->first_stream_chunk < 0) {
+		uint32_t largest = afh_get_largest_chunk_size(&mmd->afd.afhi)
+			+ vsst->header_len;
+		uint8_t needed, want;
+
+		ret = num_slices(largest, fc, &needed);
+		if (ret < 0)
+			return ret;
+		if (needed > fc->fcp->data_slices_per_group)
+			PARA_WARNING_LOG("fec parms insufficient for this audio file\n");
+		want = PARA_MAX(needed, fc->fcp->data_slices_per_group);
+		if (want != k) {
+			fec_free(fc->parms);
+			fc->src_data = para_realloc(fc->src_data, want * sizeof(char *));
+			ret = fec_new(want, want + fc->fcp->slices_per_group
+				- fc->fcp->data_slices_per_group, &fc->parms);
+			if (ret < 0)
+				return ret;
+			k = want;
+			fc->num_extra_slices = 0;
+			if (k > fc->fcp->data_slices_per_group) {
+				fc->num_extra_slices = k - fc->fcp->data_slices_per_group;
+				PARA_NOTICE_LOG("using %d extra slices\n",
+					fc->num_extra_slices);
+			}
+		}
+		fc->stream_start = *now;
+		fc->first_stream_chunk = mmd->current_chunk;
+		g->first_chunk = mmd->current_chunk;
+		g->num = 0;
+	} else {
+		/* use duration of the previous group for the timing of this group */
+		set_slice_duration(fc, g);
+		g->first_chunk += g->num_chunks;
+		g->num++;
+	}
+	if (g->first_chunk >= mmd->afd.afhi.chunks_total)
+		return 0;
+	if (need_audio_header(fc, vsst)) {
+		ret = num_slices(vsst->header_len, fc, &g->num_header_slices);
+		if (ret < 0)
+			return ret;
+	} else
+		g->num_header_slices = 0;
+	afh_get_chunk(g->first_chunk, &mmd->afd.afhi, vsst->map, &start_buf,
+		&len);
+	data_slices = k - g->num_header_slices;
+	assert(data_slices);
+	max_data_size = slice_bytes * data_slices;
+	g->bytes = 0;
+	for (i = g->first_chunk; i < mmd->afd.afhi.chunks_total; i++) {
+		afh_get_chunk(i, &mmd->afd.afhi, vsst->map, &buf, &len);
+		if (g->bytes + len > max_data_size)
+			break;
+		g->bytes += len;
+	}
+	g->num_chunks = i - g->first_chunk;
+	assert(g->num_chunks);
+	fc->current_slice_num = 0;
+	if (g->num == 0)
+		set_slice_duration(fc, g);
+
+	/* setup header slices */
+	buf = vsst->header_buf;
+	for (i = 0; i < g->num_header_slices; i++) {
+		fc->src_data[i] = (const unsigned char *)buf;
+		buf += slice_bytes;
+	}
+
+	/* setup data slices */
+	buf = start_buf;
+	for (i = g->num_header_slices; i < k; i++) {
+		if (buf + slice_bytes > vsst->map + mmd->size)
+			/*
+			 * Can not use the memory mapped audio file for this
+			 * slice as it goes beyond the map. This slice will not
+			 * be fully used.
+			 */
+			break;
+		fc->src_data[i] = (const unsigned char *)buf;
+		buf += slice_bytes;
+	}
+	if (i < k) {
+		uint32_t payload_size = vsst->map + mmd->size - buf;
+		memcpy(fc->extra_src_buf, buf, payload_size);
+		fc->src_data[i] = fc->extra_src_buf;
+		i++;
+		/* use arbitrary data for all remaining slices */
+		buf = vsst->map;
+		for (; i < k; i++)
+			fc->src_data[i] = (const unsigned char *)buf;
+	}
+	PARA_DEBUG_LOG("FEC group %d: %d chunks (%d - %d), "
+		"%d header slices, %d data slices\n",
+		g->num, g->num_chunks, g->first_chunk,
+		g->first_chunk + g->num_chunks - 1,
+		g->num_header_slices, data_slices
+	);
+	/* set group start */
+	if (g->num != 0 && vsst->header_len != 0 && fc->first_stream_chunk == 0)
+		/* chunk #0 is the audio file header */
+		tv_scale(g->first_chunk - 1, chunk_tv, &tmp);
+	else
+		tv_scale(g->first_chunk - fc->first_stream_chunk,
+			chunk_tv, &tmp);
+	tv_add(&fc->stream_start, &tmp, &g->start);
+	return 1;
+}
+
+static int compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
+{
+	assert(fc->error >= 0);
+	if (fc->first_stream_chunk < 0 || fc->current_slice_num
+			== fc->fcp->slices_per_group + fc->num_extra_slices) {
+		int ret = setup_next_fec_group(fc, vsst);
+		if (ret == 0)
+			return 0;
+		if (ret < 0) {
+			PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+			PARA_ERROR_LOG("FEC client temporarily disabled\n");
+			fc->error = ret;
+			return fc->error;
+		}
+	}
+	write_fec_header(fc, vsst);
+	fec_encode(fc->parms, fc->src_data, fc->enc_buf + FEC_HEADER_SIZE,
+		fc->current_slice_num,
+		fc->fcp->max_slice_bytes - FEC_HEADER_SIZE);
+	return 1;
+}
+
+/**
+ * Return a buffer that marks the end of the stream.
+ *
+ * \param buf Result pointer.
+ * \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] = FEC_EOF_PACKET;
+	*buf = fec_eof_packet;
+	return FEC_HEADER_SIZE;
+}
+
+/**
+ * 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 *));
+	fc->enc_buf = para_calloc(fc->fcp->max_slice_bytes);
+	fc->num_extra_slices = 0;
+	fc->extra_src_buf = para_calloc(fc->fcp->max_slice_bytes);
+	fc->next_header_time.tv_sec = 0;
+	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 fc 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->current_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;
+
+		if (fc->error < 0)
+			continue;
+		if (next_slice_is_due(fc, &diff)) {
+			timeout->tv_sec = 0;
+			timeout->tv_usec = 0;
+			return;
+		}
+		/* timeout = min(timeout, diff) */
+		if (tv_diff(&diff, timeout, NULL) < 0)
+			*timeout = diff;
+	}
+}
 
-static int audio_file;
-static char *map;
+static void set_eof_barrier(struct vss_task *vsst)
+{
+	struct fec_client *fc;
+	struct timeval timeout = mmd->afd.afhi.eof_tv,
+		*chunk_tv = vss_chunk_time();
+
+	if (!chunk_tv)
+		goto out;
+	list_for_each_entry(fc, &fec_client_list, node) {
+		struct timeval group_duration;
+
+		if (fc->error < 0)
+			continue;
+		tv_scale(fc->group.num_chunks, chunk_tv, &group_duration);
+		if (tv_diff(&timeout, &group_duration, NULL) < 0)
+			timeout = group_duration;
+	}
+out:
+	tv_add(now, &timeout, &vsst->eof_barrier);
+}
 
 /**
- * check if vss status flag \a P (playing) is set
+ * Check if vss status flag \a P (playing) is set.
  *
- * \return greater than zero if playing, zero otherwise.
+ * \return Greater than zero if playing, zero otherwise.
  *
  */
 unsigned int vss_playing(void)
@@ -55,9 +528,9 @@ unsigned int vss_playing(void)
 }
 
 /**
- * check if \a N (next) status flag is set
+ * Check if the \a N (next) status flag is set.
  *
- * \return greater than zero if set, zero if not.
+ * \return Greater than zero if set, zero if not.
  *
  */
 unsigned int vss_next(void)
@@ -66,9 +539,9 @@ unsigned int vss_next(void)
 }
 
 /**
- * check if a reposition request is pending
+ * Check if a reposition request is pending.
  *
- * \return greater than zero if true, zero otherwise.
+ * \return Greater than zero if true, zero otherwise.
  *
  */
 unsigned int vss_repos(void)
@@ -77,9 +550,9 @@ unsigned int vss_repos(void)
 }
 
 /**
- * check if the vss is currently paused
+ * Check if the vss is currently paused.
  *
- * \return greater than zero if paused, zero otherwise.
+ * \return Greater than zero if paused, zero otherwise.
  *
  */
 unsigned int vss_paused(void)
@@ -89,40 +562,19 @@ unsigned int vss_paused(void)
 }
 
 /**
- * initialize the virtual streaming system
+ * Check if the vss is currently stopped.
+ *
+ * \return Greater than zero if paused, zero otherwise.
  *
- * Call the init functions of all supported audio format handlers and
- * initialize all supported senders.
  */
-void vss_init(void)
+unsigned int vss_stopped(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);
-	}
+	return (mmd->new_vss_status_flags & VSS_NEXT)
+		&& !(mmd->new_vss_status_flags & VSS_PLAYING);
 }
 
-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;
 
@@ -134,108 +586,74 @@ static int chk_barrier(const char *bname, const struct timeval *now,
 	return -1;
 }
 
-static void vss_next_chunk_time(struct timeval *due)
-{
-	struct timeval tmp;
-
-	tv_scale(mmd->chunks_sent, &mmd->afi.chunk_tv, &tmp);
-	tv_add(&tmp, &mmd->stream_start, due);
-}
-
 /*
  * != 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() && mmd->audio_format >= 0) {
+	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 (mmd->audio_format < 0 || !vss_playing() || !map)
+	if (!vss_playing() || !vsst->map)
 		return NULL;
-	vss_next_chunk_time(&next_chunk);
-	if (chk_barrier(audio_format_name(mmd->audio_format), &now, &next_chunk,
-			&the_timeout, 0) < 0)
+	compute_chunk_time(mmd->chunks_sent, &mmd->afd.afhi.chunk_tv,
+		&mmd->stream_start, &next_chunk);
+	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;
-	int i;
-	char *tmp;
 
-	PARA_NOTICE_LOG("EOF\n");
-	if (!map) {
-		for (i = 0; senders[i].name; i++)
-			senders[i].shutdown_clients();
+	if (!vsst->map)
 		return;
-	}
-	gettimeofday(&now, NULL);
-	tv_add(&mmd->afi.eof_tv, &now, &eof_barrier);
-	munmap(map, mmd->size);
-	map = NULL;
-	close(audio_file);
-	mmd->audio_format = -1;
+	if (mmd->new_vss_status_flags & VSS_NOMORE)
+		mmd->new_vss_status_flags = VSS_NEXT;
+	set_eof_barrier(vsst);
+	para_munmap(vsst->map, mmd->size);
+	vsst->map = NULL;
 	mmd->chunks_sent = 0;
 	mmd->offset = 0;
-	mmd->afi.seconds_total = 0;
-	free(mmd->afi.chunk_table);
-	mmd->afi.chunk_table = NULL;
-	tmp  = make_message("%s:\n%s:\n%s:\n", status_item_list[SI_AUDIO_INFO1],
-		status_item_list[SI_AUDIO_INFO2], status_item_list[SI_AUDIO_INFO3]);
-	strcpy(mmd->afi.info_string, tmp);
-	free(tmp);
-	tmp  = make_message("%s:\n%s:\n%s:\n", status_item_list[SI_DBINFO1],
-		status_item_list[SI_DBINFO2], status_item_list[SI_DBINFO3]);
-	strcpy(mmd->selector_info, tmp);
-	free(tmp);
-	mmd->filename[0] = '\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;
+	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]);
+	make_empty_status_items(mmd->afd.verbose_ls_output);
+	mmd->mtime = 0;
 	mmd->size = 0;
 	mmd->events++;
 }
 
 /**
- * Get the header of the current audio file.
- *
- * \param header_len the length of the header is stored here
- *
- * \return a pointer to a buffer containing the header, or NULL, if no audio
- * file is selected or if the current audio format does not need special header
- * treamtment.
- *
- */
-char *vss_get_header(size_t *header_len)
-{
-	if (mmd->audio_format < 0 || !map || !mmd->afi.header_len)
-		return NULL;
-	*header_len = mmd->afi.header_len;
-	return map + mmd->afi.header_offset;
-}
-
-/**
- * get the list of all supported audio formats
+ * Get the list of all supported audio formats.
  *
- * \return a space separated list of all supported audio formats
+ * \return Aa space separated list of all supported audio formats
  * It is not allocated at runtime, i.e. there is no need to free
  * the returned string in the caller.
  */
@@ -244,32 +662,29 @@ 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 (mmd->audio_format < 0)
-		return NULL;
-	return &mmd->afi.chunk_tv;
+	struct timeval diff;
+
+	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 (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;
 }
 
-enum afs_socket_status {
-	AFS_SOCKET_READY,
-	AFS_SOCKET_CHECK_FOR_WRITE,
-	AFS_SOCKET_AFD_PENDING
-};
-
-static enum afs_socket_status afsss;
-
 /**
- * Compute the timeout for para_server's main select-loop.
+ * Compute the timeout for the main select-loop of the scheduler.
  *
- * This function gets called from para_server to determine the timeout value
- * for its main select loop.
+ * \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.
@@ -278,59 +693,55 @@ static enum afs_socket_status afsss;
  * 	- 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 *tv;
+	struct timeval *tv, diff;
+	struct vss_task *vsst = container_of(t, struct vss_task, task);
 
-	para_fd_set(afs_socket, rfds, max_fileno);
-	if (!map)
+	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();
-	else {
-		if (vss_next()) {
-			vss_eof();
-			return vss_compute_timeout();
+			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;
+			fc->error = 0;
 		}
+		mmd->stream_start.tv_sec = 0;
+		mmd->stream_start.tv_usec = 0;
 	}
-	if (vss_paused() || vss_repos()) {
-		for (i = 0; senders[i].name; i++)
-			senders[i].shutdown_clients();
-		if (map) {
-			struct timeval now;
-			gettimeofday(&now, NULL);
-			if (!vss_paused() || mmd->chunks_sent)
-				tv_add(&mmd->afi.eof_tv, &now, &eof_barrier);
-			if (vss_repos())
-				tv_add(&now, &announce_tv, &data_send_barrier);
-			if (mmd->new_vss_status_flags & VSS_NOMORE)
-				mmd->new_vss_status_flags = VSS_NEXT;
-		}
+	if (vss_next())
+		vss_eof(vsst);
+	else if (vss_paused()) {
+		if (mmd->chunks_sent)
+			set_eof_barrier(vsst);
+		mmd->chunks_sent = 0;
+	} else if (vss_repos()) {
+		tv_add(now, &vsst->announce_tv, &vsst->data_send_barrier);
+		set_eof_barrier(vsst);
 		mmd->chunks_sent = 0;
-	}
-	if (vss_repos()) {
-		mmd->new_vss_status_flags &= ~(VSS_REPOS);
 		mmd->current_chunk = mmd->repos_request;
+		mmd->new_vss_status_flags &= ~VSS_REPOS;
 	}
-	tv = vss_compute_timeout();
-	if (tv)
-		return tv;
-	if (!map && vss_playing() &&
-			!(mmd->new_vss_status_flags & VSS_NOMORE)) {
-		PARA_DEBUG_LOG("%s", "ready and playing, but no audio file\n");
-		if (afsss == AFS_SOCKET_READY) {
-			para_fd_set(afs_socket, wfds, max_fileno);
-			afsss = AFS_SOCKET_CHECK_FOR_WRITE;
-		}
+	if (need_to_request_new_audio_file(vsst)) {
+		PARA_DEBUG_LOG("ready and playing, but no audio file\n");
+		para_fd_set(vsst->afs_socket, &s->wfds, &s->max_fileno);
+		vsst->afsss = AFS_SOCKET_CHECK_FOR_WRITE;
+	} else
+		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(&s->max_fileno, &s->rfds, &s->wfds);
 	}
-	return tv;
+	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};
@@ -338,6 +749,7 @@ static int recv_afs_msg(int *fd, uint32_t *code, uint32_t *data)
 	struct iovec iov;
 	int ret = 0;
 
+	*fd = -1;
 	iov.iov_base = buf;
 	iov.iov_len = sizeof(buf);
 	msg.msg_iov = &iov;
@@ -349,163 +761,224 @@ static int recv_afs_msg(int *fd, uint32_t *code, uint32_t *data)
 	if (ret < 0)
 		return -ERRNO_TO_PARA_ERROR(errno);
 	if (iov.iov_len != sizeof(buf))
-		return -E_SHORT_AFS_READ;
+		return -E_AFS_SHORT_READ;
 	*code = *(uint32_t*)buf;
 	*data =  *(uint32_t*)(buf + 4);
-	cmsg = CMSG_FIRSTHDR(&msg);
 	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 		if (cmsg->cmsg_level != SOL_SOCKET
 			|| cmsg->cmsg_type != SCM_RIGHTS)
-		continue;
+			continue;
 		if ((cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int) != 1)
-		continue;
+			continue;
 		*fd = *(int *)CMSG_DATA(cmsg);
 	}
 	return 1;
 }
 
-static void recv_afs_result(void)
+static void recv_afs_result(struct vss_task *vsst)
 {
-	int ret, passed_fd = -1, shmid;
+	int ret, passed_fd, shmid;
 	uint32_t afs_code = 0, afs_data = 0;
 	struct stat statbuf;
-	struct timeval now;
 
-	PARA_NOTICE_LOG("recv\n");
-	ret = recv_afs_msg(&passed_fd, &afs_code, &afs_data);
+	vsst->afsss = AFS_SOCKET_READY;
+	ret = recv_afs_msg(vsst->afs_socket, &passed_fd, &afs_code, &afs_data);
 	if (ret < 0)
 		goto err;
-	PARA_NOTICE_LOG("got the fd: %d, code: %u, shmid: %u\n",
-		passed_fd, afs_code, afs_data);
-	ret = -E_BAD_AFS_CODE;
+	PARA_DEBUG_LOG("fd: %d, code: %u, shmid: %u\n", passed_fd, afs_code,
+		afs_data);
+	ret = -E_NOFD;
 	if (afs_code != NEXT_AUDIO_FILE)
 		goto err;
-	afsss = AFS_SOCKET_READY;
+	if (passed_fd < 0)
+		goto err;
 	shmid = afs_data;
+	free(mmd->afd.afhi.info_string);
 	ret = load_afd(shmid, &mmd->afd);
 	if (ret < 0)
 		goto err;
 	shm_destroy(shmid);
-	PARA_NOTICE_LOG("next audio file: %s (%lu chunks)\n", mmd->afd.path,
-		mmd->afd.afhi.chunks_total);
 	ret = fstat(passed_fd, &statbuf);
 	if (ret < 0) {
+		PARA_ERROR_LOG("fstat error:\n");
 		ret = -ERRNO_TO_PARA_ERROR(errno);
 		goto err;
 	}
 	mmd->size = statbuf.st_size;
 	mmd->mtime = statbuf.st_mtime;
-	map = para_mmap(mmd->size, PROT_READ, MAP_PRIVATE,
-		passed_fd, 0);
-	strcpy(mmd->filename, mmd->afd.path); /* FIXME: check length */
-	mmd->afi.header_len = 0; /* default: no header */
-	mmd->audio_format = mmd->afd.afsi.audio_format_id;
+	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;
 	mmd->offset = 0;
 	mmd->events++;
 	mmd->num_played++;
-	mmd->afi = mmd->afd.afhi;
 	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);
 	if (passed_fd >= 0)
 		close(passed_fd);
-	PARA_ERROR_LOG("%s\n", PARA_STRERROR(-ret));
+	PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+	mmd->new_vss_status_flags = VSS_NEXT;
 }
 
-void vss_post_select(fd_set *rfds, fd_set *wfds)
+/**
+ * Main sending function.
+ *
+ * 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(struct vss_task *vsst)
 {
-	int ret;
+	int i, fec_active = 0;
+	struct timeval due;
+	struct fec_client *fc, *tmp_fc;
 
-	if (FD_ISSET(afs_socket, rfds))
-		recv_afs_result();
-	if (afsss != AFS_SOCKET_CHECK_FOR_WRITE || !FD_ISSET(afs_socket, wfds))
+	if (!vsst->map || !vss_playing())
+		return;
+	if (chk_barrier("eof", &vsst->eof_barrier, &due, 1) < 0)
+		return;
+	if (chk_barrier("data send", &vsst->data_send_barrier,
+			&due, 1) < 0)
+		return;
+	list_for_each_entry_safe(fc, tmp_fc, &fec_client_list, node) {
+		if (fc->error < 0)
+			continue;
+		if (!next_slice_is_due(fc, NULL)) {
+			fec_active = 1;
+			continue;
+		}
+		if (compute_next_fec_slice(fc, vsst) <= 0)
+			continue;
+		PARA_DEBUG_LOG("sending %d:%d (%u bytes)\n", fc->group.num,
+			fc->current_slice_num, fc->fcp->max_slice_bytes);
+		fc->fcp->send((char *)fc->enc_buf,
+			fc->fcp->max_slice_bytes,
+			fc->fcp->private_data);
+		fc->current_slice_num++;
+		fec_active = 1;
+	}
+	if (mmd->current_chunk >= mmd->afd.afhi.chunks_total) { /* eof */
+		if (!fec_active)
+			mmd->new_vss_status_flags |= VSS_NEXT;
 		return;
-	PARA_NOTICE_LOG("requesting new socket\n");
-	ret = send_buffer(afs_socket, "new");
-	afsss = AFS_SOCKET_AFD_PENDING;
+	}
+	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;
+
+		if (!mmd->chunks_sent) {
+			struct timeval tmp;
+			mmd->stream_start = *now;
+			tv_scale(mmd->current_chunk, &mmd->afd.afhi.chunk_tv, &tmp);
+			mmd->offset = tv2ms(&tmp);
+			mmd->events++;
+		}
+		/*
+		 * 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);
+		}
+		mmd->chunks_sent++;
+		mmd->current_chunk++;
+	}
 }
 
-static void get_chunk(long unsigned chunk_num, char **buf, size_t *len)
+static void vss_post_select(struct sched *s, struct task *t)
 {
-	size_t pos = mmd->afi.chunk_table[chunk_num];
-	*buf = map + pos;
-	*len = mmd->afi.chunk_table[chunk_num + 1] - pos;
+	int ret, i;
+	struct vss_task *vsst = container_of(t, struct vss_task, task);
 
-	if (chunk_num + 5 > mmd->afd.afhi.chunks_total)
-		PARA_NOTICE_LOG("chunk %lu/%lu\n, len: %zu\n", chunk_num,
-			mmd->afd.afhi.chunks_total, *len);
-}
 
-/**
- * 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 Positive on success, negative on errors.
- */
-int vss_get_chunk(long unsigned chunk_num, char **buf, size_t *len)
-{
-	if (mmd->audio_format < 0 || !map || !vss_playing())
-		return -E_CHUNK;
-	if (chunk_num >= mmd->afi.chunks_total)
-		return -E_CHUNK;
-	get_chunk(chunk_num, buf, len);
-	return 1;
+	if (mmd->sender_cmd_data.cmd_num >= 0) {
+		int num = mmd->sender_cmd_data.cmd_num,
+			sender_num = mmd->sender_cmd_data.sender_num;
+
+		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 (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(vsst->afs_socket, "new");
+		if (ret < 0)
+			PARA_CRIT_LOG("%s\n", para_strerror(-ret));
+		else
+			vsst->afsss = AFS_SOCKET_AFD_PENDING;
+	}
+	for (i = 0; senders[i].name; i++) {
+		if (!senders[i].post_select)
+			continue;
+		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);
 }
 
 /**
- * main sending function
+ * Initialize the virtual streaming system task.
+ *
+ * \param afs_socket The fd for communication with afs.
  *
- * This function gets called from para_server as soon as the next chunk of
- * data should be pushed out. It first calls the read_chunk() function of
- * the current audio format handler to obtain a pointer to the data to be
- * sent out as well as its length. This information is then passed to each
- * supported sender's send() function which does the actual sending.
+ * This also initializes all supported senders and starts streaming
+ * if the --autoplay command line flag was given.
  */
-void vss_send_chunk(void)
+void init_vss_task(int afs_socket)
 {
+	static struct vss_task vss_task_struct, *vsst = &vss_task_struct;
 	int i;
-	struct timeval now, due;
-	char *buf;
-	size_t len;
-
-	if (mmd->audio_format < 0 || !map || !vss_playing())
-		return;
-	gettimeofday(&now, NULL);
-	vss_next_chunk_time(&due);
-	if (tv_diff(&due, &now, NULL) > 0)
-		return;
-	if (chk_barrier("eof", &now, &eof_barrier, &due, 1) < 0)
-		return;
-	if (chk_barrier("data send", &now, &data_send_barrier,
-			&due, 1) < 0)
-		return;
-	mmd->new_vss_status_flags &= ~VSS_REPOS;
-	if (mmd->current_chunk >= mmd->afi.chunks_total) { /* eof */
-		mmd->new_vss_status_flags |= VSS_NEXT;
-		return vss_eof();
+	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->header_interval.tv_sec = 5; /* should this be configurable? */
+	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));
+	INIT_LIST_HEAD(&fec_client_list);
+	for (i = 0; senders[i].name; i++) {
+		PARA_NOTICE_LOG("initializing %s sender\n", senders[i].name);
+		senders[i].init(&senders[i]);
 	}
-	/*
-	 * 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) {
+	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;
-		gettimeofday(&mmd->stream_start, NULL);
-		tv_scale(mmd->current_chunk, &mmd->afi.chunk_tv, &tmp);
-		mmd->offset = tv2ms(&tmp);
-		mmd->events++;
+		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);
 	}
-	get_chunk(mmd->current_chunk, &buf, &len);
-	for (i = 0; senders[i].name; i++)
-		senders[i].send(mmd->current_chunk, mmd->chunks_sent, buf, len);
-	mmd->new_vss_status_flags |= VSS_PLAYING;
-	mmd->chunks_sent++;
-	mmd->current_chunk++;
+	register_task(&vsst->task);
 }