+/**
+ * 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;
+}
+
+/* set group start and group duration */
+static void set_group_timing(struct fec_client *fc, struct fec_group *g)
+{
+ struct timeval *chunk_tv = vss_chunk_time();
+
+ 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 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 fec_group *g = &fc->group;
+ unsigned slice_bytes = fc->fcp->max_slice_bytes - FEC_HEADER_SIZE;
+ uint32_t max_data_size;
+
+ if (fc->first_stream_chunk < 0) {
+ uint8_t hs, ds; /* needed header/data slices */
+ uint8_t rs = fc->fcp->slices_per_group
+ - fc->fcp->data_slices_per_group; /* redundant slices */
+ int n;
+
+ ret = num_slices(vsst->header_len, fc, &hs);
+ if (ret < 0)
+ return ret;
+ ret = num_slices(afh_get_largest_chunk_size(&mmd->afd.afhi),
+ fc, &ds);
+ if (ret < 0)
+ return ret;
+ k = (int)hs + ds;
+ if (k > 255)
+ return -E_BAD_CT;
+ if (k < fc->fcp->data_slices_per_group)
+ k = fc->fcp->data_slices_per_group;
+ n = k + rs;
+ fc->num_extra_slices = k - fc->fcp->data_slices_per_group;
+ PARA_NOTICE_LOG("fec parms %d:%d:%d (%d extra slices)\n",
+ slice_bytes, k, n, fc->num_extra_slices);
+ fec_free(fc->parms);
+ fc->src_data = para_realloc(fc->src_data, k * sizeof(char *));
+ ret = fec_new(k, n, &fc->parms);
+ if (ret < 0)
+ return ret;
+ fc->stream_start = *now;
+ fc->first_stream_chunk = mmd->current_chunk;
+ 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);
+ k = fc->fcp->data_slices_per_group + fc->num_extra_slices;
+ set_group_timing(fc, g);
+ g->first_chunk += g->num_chunks;
+ g->num++;
+ }
+ 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_group_timing(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
+ );
+ return 1;
+}
+
+static int compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
+{
+ 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->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->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 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);
+ 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;
+
+ list_for_each_entry(fc, &fec_client_list, node) {
+ struct timeval diff;
+
+ if (fc->state != FEC_STATE_READY_TO_RUN)
+ 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 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);
+}
+