]> git.tuebingen.mpg.de Git - paraslash.git/blobdiff - vss.c
vss: Mmap audio files using MAP_POPULATE.
[paraslash.git] / vss.c
diff --git a/vss.c b/vss.c
index f33b95acd98b2774a29f59d899820fe216e73cd5..e833543e785788876af91d691b73cf8876899de3 100644 (file)
--- a/vss.c
+++ b/vss.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1997-2008 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 1997-2011 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
  * senders.
  */
 
-#include <dirent.h>
+#include <regex.h>
+#include <osl.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 "send.h"
+#include "vss.h"
 #include "ipc.h"
 #include "fd.h"
 #include "sched.h"
@@ -32,7 +35,7 @@ extern struct misc_meta_data *mmd;
 
 extern void dccp_send_init(struct sender *);
 extern void http_send_init(struct sender *);
-extern void ortp_send_init(struct sender *);
+extern void udp_send_init(struct sender *);
 
 /** The list of supported senders. */
 struct sender senders[] = {
@@ -44,12 +47,10 @@ struct sender senders[] = {
                .name = "dccp",
                .init = dccp_send_init,
        },
-#ifdef HAVE_ORTP
        {
-               .name = "ortp",
-               .init = ortp_send_init,
+               .name = "udp",
+               .init = udp_send_init,
        },
-#endif
        {
                .name = NULL,
        }
@@ -67,18 +68,646 @@ enum afs_socket_status {
 
 /** 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;
-       const char *header_buf;
+       /** Pointer to the header of the mapped audio file. */
+       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 duration of the full group. */
+       struct timeval duration;
+       /** 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;
+       /** Number of bytes per slice for this group. */
+       uint16_t slice_bytes;
+};
+
+enum fec_client_state {
+       FEC_STATE_NONE = 0,     /**< not initialized and not enabled */
+       FEC_STATE_DISABLED,     /**< temporarily disabled */
+       FEC_STATE_READY_TO_RUN  /**< initialized and enabled */
+};
+
+/**
+ * Describes one connected FEC client.
+ */
+struct fec_client {
+       /** Current state of the client */
+       enum fec_client_state state;
+       /** The connected sender client (transport layer). */
+       struct sender_client *sc;
+       /** 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;
+       /** Needed for the last slice of the audio file header. */
+       unsigned char *extra_header_buf;
+       /** Extra slices needed to store largest chunk + header. */
+       int num_extra_slices;
+       /** Contains the FEC-encoded data. */
+       unsigned char *enc_buf;
+       /** Maximal packet size. */
+       int mps;
 };
 
+/**
+ * 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_u8(buf + 19, 0); /* unused */
+       write_u16(buf + 20, g->slice_bytes);
+       write_u8(buf + 22, g->first_chunk? 0 : 1);
+       write_u8(buf + 23, vsst->header_len? 1 : 0);
+       memset(buf + 24, 0, 8);
+}
+
+static bool 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 false;
+       }
+       if (!vsst->header_buf)
+               return false;
+       if (vsst->header_len == 0)
+               return false;
+       if (fc->group.num > 0) {
+               if (!fc->fcp->need_periodic_header)
+                       return false;
+               if (tv_diff(&fc->next_header_time, now, NULL) > 0)
+                       return false;
+       }
+       tv_add(now, &vsst->header_interval, &fc->next_header_time);
+       return true;
+}
+
+static bool need_data_slices(struct fec_client *fc, struct vss_task *vsst)
+{
+       if (fc->group.num > 0)
+               return true;
+       if (!vsst->header_buf)
+               return true;
+       if (vsst->header_len == 0)
+               return true;
+       if (fc->fcp->need_periodic_header)
+               return true;
+       return false;
+}
+
+static int num_slices(long unsigned bytes, int max_payload, int rs)
+{
+       int ret;
+
+       assert(max_payload > 0);
+       assert(rs > 0);
+       ret = DIV_ROUND_UP(bytes, max_payload);
+       if (ret + rs > 255)
+               return -E_BAD_CT;
+       return ret;
+}
+
+/* set group start and group duration */
+static void set_group_timing(struct fec_client *fc, struct vss_task *vsst)
+{
+       struct fec_group *g = &fc->group;
+       struct timeval *chunk_tv = vss_chunk_time();
+
+       if (!need_data_slices(fc, vsst))
+               ms2tv(200, &g->duration);
+       else
+               tv_scale(g->num_chunks, chunk_tv, &g->duration);
+       tv_divide(fc->fcp->slices_per_group + fc->num_extra_slices,
+               &g->duration, &g->slice_duration);
+       PARA_DEBUG_LOG("durations (group/chunk/slice): %lu/%lu/%lu\n",
+               tv2ms(&g->duration), tv2ms(chunk_tv), tv2ms(&g->slice_duration));
+}
+
+static int initialize_fec_client(struct fec_client *fc, struct vss_task *vsst)
+{
+       int k, n, ret;
+       int hs, ds, rs; /* header/data/redundant slices */
+       struct fec_client_parms *fcp = fc->fcp;
+
+       /* set mps */
+       if (fcp->init_fec) {
+               /*
+                * Set the maximum slice size to the Maximum Packet Size if the
+                * transport protocol allows to determine this value. The user
+                * can specify a slice size up to this value.
+                */
+               ret = fcp->init_fec(fc->sc);
+               if (ret < 0)
+                       return ret;
+               fc->mps = ret;
+       } else
+               fc->mps = generic_max_transport_msg_size(fc->sc->fd);
+       if (fc->mps <= FEC_HEADER_SIZE)
+               return -ERRNO_TO_PARA_ERROR(EINVAL);
+
+       rs = fc->fcp->slices_per_group - fc->fcp->data_slices_per_group;
+       ret = num_slices(vsst->header_len, fc->mps - FEC_HEADER_SIZE, rs);
+       if (ret < 0)
+               return ret;
+       hs = ret;
+       ret = num_slices(mmd->afd.max_chunk_size, fc->mps - FEC_HEADER_SIZE, rs);
+       if (ret < 0)
+               return ret;
+       ds = ret;
+       if (fc->fcp->need_periodic_header)
+               k = hs + ds;
+       else
+               k = PARA_MAX(hs, ds);
+       if (k < fc->fcp->data_slices_per_group)
+               k = fc->fcp->data_slices_per_group;
+       fc->num_extra_slices = k - fc->fcp->data_slices_per_group;
+       n = k + rs;
+       fec_free(fc->parms);
+       ret = fec_new(k, n, &fc->parms);
+       if (ret < 0)
+               return ret;
+       PARA_INFO_LOG("mps: %d, k: %d, n: %d, extra slices: %d\n",
+               fc->mps, k, n, fc->num_extra_slices);
+       fc->src_data = para_realloc(fc->src_data, k * sizeof(char *));
+       fc->enc_buf = para_realloc(fc->enc_buf, fc->mps);
+       fc->extra_src_buf = para_realloc(fc->extra_src_buf, fc->mps);
+       fc->extra_header_buf = para_realloc(fc->extra_header_buf, fc->mps);
+
+       fc->state = FEC_STATE_READY_TO_RUN;
+       fc->next_header_time.tv_sec = 0;
+       fc->stream_start = *now;
+       fc->first_stream_chunk = mmd->current_chunk;
+       return 1;
+}
+
+static void vss_get_chunk(int chunk_num, struct vss_task *vsst,
+               char **buf, size_t *sz)
+{
+       /*
+        * Chunk zero is special for header streams: It is the first portion of
+        * the audio file which consists of the audio file header. It may be
+        * arbitrary large due to embedded meta data. Audio format handlers may
+        * replace the header by a stripped one with meta data omitted which is
+        * of bounded size. We always use the stripped header for streaming
+        * rather than the unmodified header (chunk zero).
+        */
+       if (chunk_num == 0 && vsst->header_len > 0) {
+               *buf = vsst->header_buf; /* stripped header */
+               *sz = vsst->header_len;
+               return;
+       }
+       afh_get_chunk(chunk_num, &mmd->afd.afhi, vsst->map, (const char **)buf,
+               sz);
+}
+
+static void compute_group_size(struct vss_task *vsst, struct fec_group *g,
+               int max_bytes)
+{
+       int i, max_chunks = PARA_MAX(1LU, 150 / tv2ms(vss_chunk_time()));
+
+       g->num_chunks = 0;
+       g->bytes = 0;
+       /*
+        * Include chunks into the group until the group duration is at least
+        * 150ms.  For ogg and wma, a single chunk's duration (ogg page/wma
+        * super frame) is already larger than 150ms, so a FEC group consists
+        * of exactly one chunk for these audio formats.
+        */
+       for (i = 0;; i++) {
+               char *buf;
+               size_t len;
+               int chunk_num = g->first_chunk + i;
+
+               if (g->bytes > 0 && i >= max_chunks) /* duration limit */
+                       break;
+               if (chunk_num >= mmd->afd.afhi.chunks_total) /* eof */
+                       break;
+               vss_get_chunk(chunk_num, vsst, &buf, &len);
+               if (g->bytes + len > max_bytes)
+                       break;
+               /* Include this chunk */
+               g->bytes += len;
+               g->num_chunks++;
+       }
+       assert(g->num_chunks);
+}
+
+/*
+ * Compute the slice size of the next group.
+ *
+ * The FEC parameters n and k are fixed but the slice size varies per
+ * FEC group.  We'd like to choose slices as small as possible to avoid
+ * unnecessary FEC calculations but large enough to guarantee that the
+ * k data slices suffice to encode the header (if needed) and the data
+ * chunk(s).
+ *
+ * Once we know the payload of the next group, we define the number s
+ * of bytes per slice for this group by
+ *
+ *     s = ceil(payload / k)
+ *
+ * However, for header streams, computing s is more complicated since no
+ * overlapping of header and data slices is possible. Hence we have k >=
+ * 2 and s must satisfy
+ *
+ * (*) ceil(h / s) + ceil(d / s) <= k
+ *
+ * where h and d are payload of the header and the data chunk(s)
+ * respectively. In general there is no value for s such that (*)
+ * becomes an equality, for example if h = 4000, d = 5000 and k = 10.
+ *
+ * We use the following approach for computing a suitable value for s:
+ *
+ * Let
+ *     k1 := ceil(k * min(h, d) / (h + d)),
+ *     k2 := k - k1.
+ *
+ * Note that k >= 2 implies k1 > 0 and k2 > 0, so
+ *
+ *     s := max(ceil(min(h, d) / k1), ceil(max(h, d) / k2))
+ *
+ * is well-defined. Inequality (*) holds for this value of s since k1
+ * slices suffice to store min(h, d) while k2 slices suffice to store
+ * max(h, d), i.e. the first addent of (*) is bounded by k1 and the
+ * second by k2.
+ *
+ * For the above example we obtain
+ *
+ *     k1 = ceil(10 * 4000 / 9000) = 5, k2 = 5,
+ *     s = max(4000 / 5, 5000 / 5) = 1000,
+ *
+ * which is optimal since a slice size of 999 bytes would already require
+ * 11 slices.
+ */
+static int compute_slice_size(struct fec_client *fc, struct vss_task *vsst)
+{
+       struct fec_group *g = &fc->group;
+       int k = fc->fcp->data_slices_per_group + fc->num_extra_slices;
+       int n = fc->fcp->slices_per_group + fc->num_extra_slices;
+       int ret, k1, k2, h, d, min, max, sum;
+       int max_slice_bytes = fc->mps - FEC_HEADER_SIZE;
+       int max_group_bytes;
+
+       if (!need_audio_header(fc, vsst)) {
+               max_group_bytes = k * max_slice_bytes;
+               g->num_header_slices = 0;
+               compute_group_size(vsst, g, max_group_bytes);
+               g->slice_bytes = DIV_ROUND_UP(g->bytes, k);
+               if (g->slice_bytes == 0)
+                       g->slice_bytes = 1;
+               return 1;
+       }
+       if (!need_data_slices(fc, vsst)) {
+               g->bytes = 0;
+               g->num_chunks = 0;
+               g->slice_bytes = DIV_ROUND_UP(vsst->header_len, k);
+               g->num_header_slices = k;
+               return 1;
+       }
+       h = vsst->header_len;
+       max_group_bytes = (k - num_slices(h, max_slice_bytes, n - k))
+               * max_slice_bytes;
+       compute_group_size(vsst, g, max_group_bytes);
+       d = g->bytes;
+       if (d == 0) {
+               g->slice_bytes = DIV_ROUND_UP(h, k);
+               ret = num_slices(vsst->header_len, g->slice_bytes, n - k);
+               if (ret < 0)
+                       return ret;
+               g->num_header_slices = ret;
+               return 1;
+       }
+       min = PARA_MIN(h, d);
+       max = PARA_MAX(h, d);
+       sum = h + d;
+       k1 = DIV_ROUND_UP(k * min, sum);
+       k2 = k - k1;
+       assert(k1 > 0);
+       assert(k2 > 0);
+
+       g->slice_bytes = PARA_MAX(DIV_ROUND_UP(min, k1), DIV_ROUND_UP(max, k2));
+       /*
+        * This value of s := g->slice_bytes satisfies inequality (*) above,
+        * but it might be larger than max_slice_bytes. However, we know that
+        * max_slice_bytes are sufficient to store header and data, so:
+        */
+       g->slice_bytes = PARA_MIN((int)g->slice_bytes, max_slice_bytes);
+
+       ret = num_slices(vsst->header_len, g->slice_bytes, n - k);
+       if (ret < 0)
+               return ret;
+       g->num_header_slices = ret;
+       return 1;
+}
+
+static int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
+{
+       int ret, i, k, n, data_slices;
+       size_t len;
+       char *buf;
+       struct fec_group *g = &fc->group;
+
+       if (fc->state == FEC_STATE_NONE) {
+               ret = initialize_fec_client(fc, vsst);
+               if (ret < 0)
+                       return ret;
+               g->first_chunk = mmd->current_chunk;
+               g->num = 0;
+               g->start = *now;
+       } else {
+               struct timeval tmp;
+               if (g->first_chunk + g->num_chunks >= mmd->afd.afhi.chunks_total)
+                       return 0;
+               /*
+                * Start and duration of this group depend only on the previous
+                * group. Compute the new group start as g->start += g->duration.
+                */
+               tmp = g->start;
+               tv_add(&tmp, &g->duration, &g->start);
+               set_group_timing(fc, vsst);
+               g->first_chunk += g->num_chunks;
+               g->num++;
+       }
+       k = fc->fcp->data_slices_per_group + fc->num_extra_slices;
+       n = fc->fcp->slices_per_group + fc->num_extra_slices;
+
+       compute_slice_size(fc, vsst);
+       assert(g->slice_bytes > 0);
+       ret = num_slices(g->bytes, g->slice_bytes, n - k);
+       if (ret < 0)
+               return ret;
+       data_slices = ret;
+       assert(g->num_header_slices + data_slices <= k);
+       fc->current_slice_num = 0;
+       if (g->num == 0)
+               set_group_timing(fc, vsst);
+       /* setup header slices */
+       buf = vsst->header_buf;
+       for (i = 0; i < g->num_header_slices; i++) {
+               uint32_t payload_size;
+               if (buf + g->slice_bytes <= vsst->header_buf + vsst->header_len) {
+                       fc->src_data[i] = (const unsigned char *)buf;
+                       buf += g->slice_bytes;
+                       continue;
+               }
+               /*
+                * Can not use vss->header_buf for this slice as it
+                * goes beyond the buffer. This slice will not be fully
+                * used.
+                */
+               payload_size = vsst->header_buf + vsst->header_len - buf;
+               memcpy(fc->extra_header_buf, buf, payload_size);
+               if (payload_size < g->slice_bytes)
+                       memset(fc->extra_header_buf + payload_size, 0,
+                               g->slice_bytes - payload_size);
+               fc->src_data[i] = fc->extra_header_buf;
+               assert(i == g->num_header_slices - 1);
+       }
+
+       /* setup data slices */
+       vss_get_chunk(g->first_chunk, vsst, &buf, &len);
+       for (; i < g->num_header_slices + data_slices; i++) {
+               if (buf + g->slice_bytes > vsst->map + mmd->size) {
+                       /*
+                        * Can not use the memory mapped audio file for this
+                        * slice as it goes beyond the map.
+                        */
+                       uint32_t payload_size = vsst->map + mmd->size - buf;
+                       memcpy(fc->extra_src_buf, buf, payload_size);
+                       if (payload_size < g->slice_bytes)
+                               memset(fc->extra_src_buf + payload_size, 0,
+                                       g->slice_bytes - payload_size);
+                       fc->src_data[i] = fc->extra_src_buf;
+                       i++;
+                       break;
+               }
+               fc->src_data[i] = (const unsigned char *)buf;
+               buf += g->slice_bytes;
+       }
+       if (i < k) {
+               /* 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 bytes\n",
+               g->num, g->num_chunks, g->first_chunk,
+               g->first_chunk + g->num_chunks - 1, g->bytes
+       );
+       PARA_DEBUG_LOG("slice_bytes: %d, %d header slices, %d data slices\n",
+               g->slice_bytes, g->num_header_slices, data_slices
+       );
+       return 1;
+}
+
+static int compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
+{
+       if (fc->state == FEC_STATE_NONE || 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->state = FEC_STATE_DISABLED;
+                       return ret;
+               }
+       }
+       write_fec_header(fc, vsst);
+       fec_encode(fc->parms, fc->src_data, fc->enc_buf + FEC_HEADER_SIZE,
+               fc->current_slice_num, fc->group.slice_bytes);
+       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 sc  Generic sender_client data of the transport layer.
+ * \param fcp FEC parameters as supplied by the transport layer.
+ *
+ * \return Newly allocated fec_client struct.
+ */
+struct fec_client *vss_add_fec_client(struct sender_client *sc,
+                                     struct fec_client_parms *fcp)
+{
+       struct fec_client *fc = para_calloc(sizeof(*fc));
+
+       fc->sc  = sc;
+       fc->fcp = fcp;
+       para_list_add(&fc->node, &fec_client_list);
+       return fc;
+}
+
+/**
+ * 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);
+       free(fc->extra_header_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->state == FEC_STATE_NONE)
+               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 set_eof_barrier(struct vss_task *vsst)
+{
+       struct fec_client *fc;
+       struct timeval timeout = {1, 0}, *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->state != FEC_STATE_READY_TO_RUN)
+                       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.
  *
@@ -149,95 +778,68 @@ static int chk_barrier(const char *bname, const struct timeval *barrier,
        return -1;
 }
 
-/*
- * != NULL: timeout for next chunk
- * NULL: nothing to do
- */
-static struct timeval *vss_compute_timeout(struct vss_task *vsst)
+static void vss_compute_timeout(struct sched *s, struct vss_task *vsst)
 {
-       static struct timeval the_timeout;
-       struct timeval next_chunk;
+       struct timeval tv;
+       struct fec_client *fc;
 
-       if (vss_next() && vsst->map) {
-               /* only sleep a bit, nec*/
-               the_timeout.tv_sec = 0;
-               the_timeout.tv_usec = 100;
-               return &the_timeout;
-       }
-       if (chk_barrier("autoplay_delay", &vsst->autoplay_barrier,
-                       &the_timeout, 1) < 0)
-               return &the_timeout;
-       if (chk_barrier("eof", &vsst->eof_barrier, &the_timeout, 1) < 0)
-               return &the_timeout;
-       if (chk_barrier("data send", &vsst->data_send_barrier,
-                       &the_timeout, 1) < 0)
-               return &the_timeout;
        if (!vss_playing() || !vsst->map)
-               return NULL;
+               return;
+       if (vss_next() && vsst->map) /* only sleep a bit, nec*/
+               return sched_request_timeout_ms(100, s);
+
+       /* Each of these barriers must have passed until we may proceed */
+       if (sched_request_barrier(&vsst->autoplay_barrier, s) == 1)
+               return;
+       if (sched_request_barrier(&vsst->eof_barrier, s) == 1)
+               return;
+       if (sched_request_barrier(&vsst->data_send_barrier, s) == 1)
+               return;
+       /*
+        * Compute the select timeout as the minimal time until the next
+        * chunk/slice is due for any client.
+        */
        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)
-               return &the_timeout;
-       /* chunk is due or bof */
-       the_timeout.tv_sec = 0;
-       the_timeout.tv_usec = 0;
-       return &the_timeout;
+               &mmd->stream_start, &tv);
+       if (sched_request_barrier_or_min_delay(&tv, s) == 0)
+               return;
+       list_for_each_entry(fc, &fec_client_list, node) {
+               if (fc->state != FEC_STATE_READY_TO_RUN)
+                       continue;
+               if (next_slice_is_due(fc, &tv))
+                       return sched_min_delay(s);
+               sched_request_timeout(&tv, s);
+       }
 }
 
 static void vss_eof(struct vss_task *vsst)
 {
-       mmd->stream_start = *now;
+
        if (!vsst->map)
                return;
        if (mmd->new_vss_status_flags & VSS_NOMORE)
                mmd->new_vss_status_flags = VSS_NEXT;
-       tv_add(&mmd->afd.afhi.eof_tv, now, &vsst->eof_barrier);
+       set_eof_barrier(vsst);
+       afh_free_header(vsst->header_buf, mmd->afd.audio_format_id);
+       vsst->header_buf = NULL;
        para_munmap(vsst->map, mmd->size);
        vsst->map = NULL;
        mmd->chunks_sent = 0;
-       mmd->offset = 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;
-       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 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.
- */
-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)
-{
-       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 int need_to_request_new_audio_file(struct vss_task *vsst)
 {
+       struct timeval diff;
+
        if (vsst->map) /* have audio file */
                return 0;
        if (!vss_playing()) /* don't need one */
@@ -246,14 +848,21 @@ static int need_to_request_new_audio_file(struct vss_task *vsst)
                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;
 }
 
+static void set_mmd_offset(void)
+{
+       struct timeval offset;
+       tv_scale(mmd->current_chunk, &mmd->afd.afhi.chunk_tv, &offset);
+       mmd->offset = tv2ms(&offset);
+}
+
 /**
- * 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.
+ * Compute the timeout for the main select-loop of the scheduler.
  *
  * \param s Pointer to the server scheduler.
  * \param t Pointer to the vss task structure.
@@ -269,26 +878,32 @@ static int need_to_request_new_audio_file(struct vss_task *vsst)
 static void vss_pre_select(struct sched *s, struct task *t)
 {
        int i;
-       struct timeval *tv, diff;
        struct vss_task *vsst = container_of(t, struct vss_task, task);
 
-       if (!vsst->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->state = FEC_STATE_NONE;
+               mmd->stream_start.tv_sec = 0;
+               mmd->stream_start.tv_usec = 0;
+       }
        if (vss_next())
                vss_eof(vsst);
        else if (vss_paused()) {
                if (mmd->chunks_sent)
-                       tv_add(&mmd->afd.afhi.eof_tv, now, &vsst->eof_barrier);
+                       set_eof_barrier(vsst);
                mmd->chunks_sent = 0;
        } else if (vss_repos()) {
                tv_add(now, &vsst->announce_tv, &vsst->data_send_barrier);
-               tv_add(&mmd->afd.afhi.eof_tv, now, &vsst->eof_barrier);
+               set_eof_barrier(vsst);
                mmd->chunks_sent = 0;
                mmd->current_chunk = mmd->repos_request;
                mmd->new_vss_status_flags &= ~VSS_REPOS;
+               set_mmd_offset();
        }
-
        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);
@@ -300,9 +915,7 @@ static void vss_pre_select(struct sched *s, struct task *t)
                        continue;
                senders[i].pre_select(&s->max_fileno, &s->rfds, &s->wfds);
        }
-       tv = vss_compute_timeout(vsst);
-       if (tv && tv_diff(tv, &s->timeout, &diff) < 0)
-               s->timeout = *tv;
+       vss_compute_timeout(s, vsst);
 }
 
 static int recv_afs_msg(int afs_socket, int *fd, uint32_t *code, uint32_t *data)
@@ -331,25 +944,32 @@ static int recv_afs_msg(int afs_socket, int *fd, uint32_t *code, uint32_t *data)
        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(struct vss_task *vsst)
+#ifndef MAP_POPULATE
+#define MAP_POPULATE 0
+#endif
+
+static void recv_afs_result(struct vss_task *vsst, fd_set *rfds)
 {
        int ret, passed_fd, shmid;
        uint32_t afs_code = 0, afs_data = 0;
        struct stat statbuf;
 
-       vsst->afsss = AFS_SOCKET_READY;
-       mmd->afd.afhi.chunk_table = NULL;
+       if (!FD_ISSET(vsst->afs_socket, rfds))
+               return;
        ret = recv_afs_msg(vsst->afs_socket, &passed_fd, &afs_code, &afs_data);
+       if (ret == -ERRNO_TO_PARA_ERROR(EAGAIN))
+               return;
        if (ret < 0)
                goto err;
+       vsst->afsss = AFS_SOCKET_READY;
        PARA_DEBUG_LOG("fd: %d, code: %u, shmid: %u\n", passed_fd, afs_code,
                afs_data);
        ret = -E_NOFD;
@@ -370,8 +990,10 @@ static void recv_afs_result(struct vss_task *vsst)
        }
        mmd->size = statbuf.st_size;
        mmd->mtime = statbuf.st_mtime;
-       vsst->map = para_mmap(mmd->size, PROT_READ, MAP_PRIVATE,
-               passed_fd, 0);
+       ret = para_mmap(mmd->size, PROT_READ, MAP_PRIVATE | MAP_POPULATE,
+               passed_fd, 0, &vsst->map);
+       if (ret < 0)
+               goto err;
        close(passed_fd);
        mmd->chunks_sent = 0;
        mmd->current_chunk = 0;
@@ -379,9 +1001,8 @@ static void recv_afs_result(struct vss_task *vsst)
        mmd->events++;
        mmd->num_played++;
        mmd->new_vss_status_flags &= (~VSS_NEXT);
-       tv_add(now, &vsst->announce_tv, &vsst->data_send_barrier);
-       afh_get_header(&mmd->afd.afhi, vsst->map, &vsst->header_buf,
-               &vsst->header_len);
+       afh_get_header(&mmd->afd.afhi, mmd->afd.audio_format_id,
+               vsst->map, mmd->size, &vsst->header_buf, &vsst->header_len);
        return;
 err:
        free(mmd->afd.afhi.chunk_table);
@@ -394,52 +1015,89 @@ 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(struct vss_task *vsst)
+static void vss_send(struct vss_task *vsst)
 {
-       int i;
+       int i, fec_active = 0;
        struct timeval due;
-       const char *buf;
-       size_t len;
+       struct fec_client *fc, *tmp_fc;
 
        if (!vsst->map || !vss_playing())
                return;
-       compute_chunk_time(mmd->chunks_sent, &mmd->afd.afhi.chunk_tv,
-               &mmd->stream_start, &due);
-       if (tv_diff(&due, now, NULL) > 0)
-               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->state == FEC_STATE_DISABLED)
+                       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->group.slice_bytes);
+               fc->fcp->send_fec(fc->sc, (char *)fc->enc_buf,
+                       fc->group.slice_bytes + FEC_HEADER_SIZE);
+               fc->current_slice_num++;
+               fec_active = 1;
+       }
        if (mmd->current_chunk >= mmd->afd.afhi.chunks_total) { /* eof */
-               mmd->new_vss_status_flags |= VSS_NEXT;
+               if (!fec_active)
+                       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;
-               mmd->stream_start = *now;
-               tv_scale(mmd->current_chunk, &mmd->afd.afhi.chunk_tv, &tmp);
-               mmd->offset = tv2ms(&tmp);
-               mmd->events++;
+       compute_chunk_time(mmd->chunks_sent, &mmd->afd.afhi.chunk_tv,
+               &mmd->stream_start, &due);
+       if (tv_diff(&due, now, NULL) <= 0) {
+               char *buf;
+               size_t len;
+
+               if (!mmd->chunks_sent) {
+                       mmd->stream_start = *now;
+                       mmd->events++;
+                       set_mmd_offset();
+               }
+               /*
+                * 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.
+                */
+               vss_get_chunk(mmd->current_chunk, vsst, &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++;
+               /*
+                * Prefault next chunk(s)
+                *
+                * If the backing device of the memory-mapped audio file is
+                * slow and read-ahead is turned off or prevented for some
+                * reason, e.g. due to memory pressure, it may take much longer
+                * than the chunk interval to get the next chunk on the wire,
+                * causing buffer underruns on the client side. Mapping the
+                * file with MAP_POPULATE seems to help a bit, but it does not
+                * eliminate the delays completely. Moreover, it is supported
+                * only on Linux. So we do our own read-ahead here.
+                */
+               buf += len;
+               for (i = 0; i < 5 && buf < vsst->map + mmd->size; i++) {
+                       __a_unused volatile char x = *buf;
+                       buf += 4096;
+               }
        }
-       afh_get_chunk(mmd->current_chunk, &mmd->afd.afhi, vsst->map, &buf, &len);
-       for (i = 0; senders[i].name; i++)
-               senders[i].send(mmd->current_chunk, mmd->chunks_sent, buf, len,
-                       vsst->header_buf, vsst->header_len);
-       mmd->new_vss_status_flags |= VSS_PLAYING;
-       mmd->chunks_sent++;
-       mmd->current_chunk++;
 }
 
 static void vss_post_select(struct sched *s, struct task *t)
@@ -447,28 +1105,38 @@ 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,
                        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);
+               if (senders[sender_num].client_cmds[num]) {
+                       ret = senders[sender_num].client_cmds[num]
+                               (&mmd->sender_cmd_data);
+                       if (ret < 0)
+                               PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+               }
                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)) {
+       if (vsst->afsss != AFS_SOCKET_CHECK_FOR_WRITE)
+               recv_afs_result(vsst, &s->rfds);
+       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");
-               vsst->afsss = AFS_SOCKET_AFD_PENDING;
+               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);
        }
-       vss_send_chunk(vsst);
+       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);
 }
 
 /**
@@ -488,12 +1156,13 @@ void init_vss_task(int afs_socket)
                        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]);
@@ -507,6 +1176,9 @@ void init_vss_task(int afs_socket)
                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);
        }
+       sprintf(vsst->task.status, "vss task");
        register_task(&vsst->task);
 }