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 {
write_u32(buf + 14, g->bytes);
write_u8(buf + 18, fc->current_slice_num);
- write_u16(buf + 20, fc->mps - FEC_HEADER_SIZE);
+ 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, 7);
return true;
}
-static int num_slices(long unsigned bytes, int mps, int rs)
+static int num_slices(long unsigned bytes, int max_payload, int rs)
{
- int m = mps - FEC_HEADER_SIZE;
int ret;
- assert(m > 0);
+ assert(max_payload > 0);
assert(rs > 0);
- ret = DIV_ROUND_UP(bytes, m);
+ ret = DIV_ROUND_UP(bytes, max_payload);
if (ret + rs > 255)
return -E_BAD_CT;
return ret;
static int initialize_fec_client(struct fec_client *fc, struct vss_task *vsst)
{
- int k, n, ret, mps;
+ int k, n, ret;
int hs, ds, rs; /* header/data/redundant slices */
struct fec_client_parms *fcp = fc->fcp;
ret = fcp->init_fec(fc->sc);
if (ret < 0)
return ret;
- mps = ret;
+ fc->mps = ret;
} else
- mps = generic_max_transport_msg_size(fc->sc->fd);
- if (mps <= FEC_HEADER_SIZE)
+ 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, mps, rs);
+ ret = num_slices(vsst->header_len, fc->mps - FEC_HEADER_SIZE, rs);
if (ret < 0)
goto err;
hs = ret;
- ret = num_slices(mmd->afd.max_chunk_size, mps, rs);
+ ret = num_slices(mmd->afd.max_chunk_size, fc->mps - FEC_HEADER_SIZE, rs);
if (ret < 0)
goto err;
ds = ret;
- k = ret + ds;
+ k = 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;
- PARA_CRIT_LOG("hs: %d, ds: %d, rs: %d, k: %d, n: %d\n", hs, ds, rs, k, n);
fec_free(fc->parms);
ret = fec_new(k, n, &fc->parms);
if (ret < 0)
return ret;
- fc->num_extra_slices = k - fc->fcp->data_slices_per_group;
- PARA_NOTICE_LOG("fec parms %d:%d:%d (%d extra slices)\n",
- mps, k, n, fc->num_extra_slices);
+ 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, mps);
- memset(fc->enc_buf, 0, mps);
- fc->extra_src_buf = para_realloc(fc->extra_src_buf, mps);
- memset(fc->extra_src_buf, 0, mps);
+ fc->enc_buf = para_realloc(fc->enc_buf, fc->mps);
+ fc->extra_src_buf = para_realloc(fc->extra_src_buf, fc->mps);
- fc->mps = mps;
fc->state = FEC_STATE_READY_TO_RUN;
fc->next_header_time.tv_sec = 0;
fc->stream_start = *now;
return ret;
}
+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++) {
+ const 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;
+ afh_get_chunk(chunk_num, &mmd->afd.afhi, vsst->map, &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;
+ }
+ 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;
- const char *buf, *start_buf;
+ const char *buf;
struct fec_group *g = &fc->group;
- unsigned slice_bytes;
- uint32_t max_data_size;
if (fc->state == FEC_STATE_NONE) {
ret = initialize_fec_client(fc, vsst);
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)
g->first_chunk += g->num_chunks;
g->num++;
}
- slice_bytes = fc->mps - FEC_HEADER_SIZE;
- PARA_CRIT_LOG("slice_bytes: %d\n", slice_bytes);
k = fc->fcp->data_slices_per_group + fc->num_extra_slices;
n = fc->fcp->slices_per_group + fc->num_extra_slices;
- PARA_CRIT_LOG("k: %d, n: %d\n", k, n);
- if (need_audio_header(fc, vsst)) {
- ret = num_slices(vsst->header_len, slice_bytes, n - k);
- if (ret < 0)
- return ret;
- g->num_header_slices = 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);
+
+ 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, g);
buf = vsst->header_buf;
for (i = 0; i < g->num_header_slices; i++) {
fc->src_data[i] = (const unsigned char *)buf;
- buf += slice_bytes;
+ buf += g->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)
+ afh_get_chunk(g->first_chunk, &mmd->afd.afhi, vsst->map, &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. This slice will not
* be fully used.
*/
+ 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 += slice_bytes;
+ buf += g->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",
+ 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->num_header_slices, data_slices
+ 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;
}
}
write_fec_header(fc, vsst);
fec_encode(fc->parms, fc->src_data, fc->enc_buf + FEC_HEADER_SIZE,
- fc->current_slice_num, fc->mps - FEC_HEADER_SIZE);
+ fc->current_slice_num, fc->group.slice_bytes);
return 1;
}
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->mps);
- fc->fcp->send_fec(fc->sc, (char *)fc->enc_buf, fc->mps);
+ 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;
}
projects / paraslash.git / commitdiff