+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)
+{
+ char *buf;
+ size_t len;
+ int i, max_chunks = PARA_MAX(1LU, 150 / tv2ms(vss_chunk_time()));
+
+ if (g->first_chunk == 0) {
+ g->num_chunks = 1;
+ vss_get_chunk(0, vsst, &buf, &len);
+ g->bytes = len;
+ return;
+ }
+
+ 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++) {
+ 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.