+/**
+ * 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)