FEC: Improve and simplify group timing.
[paraslash.git] / vss.c
diff --git a/vss.c b/vss.c
index 6db42bd..c6e4053 100644 (file)
--- a/vss.c
+++ b/vss.c
@@ -121,6 +121,8 @@ struct fec_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. */
@@ -232,15 +234,16 @@ static int num_slices(long unsigned bytes, struct fec_client *fc, uint8_t *resul
        return 1;
 }
 
-static void set_slice_duration(struct fec_client *fc, struct fec_group *g)
+/* set group start and group duration */
+static void set_group_timing(struct fec_client *fc, struct fec_group *g)
 {
-       struct timeval group_duration, *chunk_tv = vss_chunk_time();
+       struct timeval *chunk_tv = vss_chunk_time();
 
-       tv_scale(g->num_chunks, chunk_tv, &group_duration);
+       tv_scale(g->num_chunks, chunk_tv, &g->duration);
        tv_divide(fc->fcp->slices_per_group + fc->num_extra_slices,
-               &group_duration, &g->slice_duration);
+               &g->duration, &g->slice_duration);
        PARA_DEBUG_LOG("durations (group/chunk/slice): %lu/%lu/%lu\n",
-               tv2ms(&group_duration), tv2ms(chunk_tv), tv2ms(&g->slice_duration));
+               tv2ms(&g->duration), tv2ms(chunk_tv), tv2ms(&g->slice_duration));
 }
 
 static int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
@@ -248,12 +251,10 @@ 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 timeval tmp, *chunk_tv = vss_chunk_time();
        struct fec_group *g = &fc->group;
        unsigned slice_bytes = fc->fcp->max_slice_bytes - FEC_HEADER_SIZE;
        uint32_t max_data_size;
 
-       assert(chunk_tv);
        if (fc->first_stream_chunk < 0) {
                uint8_t hs, ds; /* needed header/data slices */
                uint8_t rs = fc->fcp->slices_per_group
@@ -285,10 +286,16 @@ static int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
                fc->first_stream_chunk = mmd->current_chunk;
                g->first_chunk = mmd->current_chunk;
                g->num = 0;
+               g->start = *now;
        } else {
+               /*
+                * Start and duration of this group depend only on the previous
+                * group. Compute the new group start as g->start += g->duration.
+                */
+               struct timeval tmp = g->start;
+               tv_add(&tmp, &g->duration, &g->start);
                k = fc->fcp->data_slices_per_group + fc->num_extra_slices;
-               /* use duration of the previous group for the timing of this group */
-               set_slice_duration(fc, g);
+               set_group_timing(fc, g);
                g->first_chunk += g->num_chunks;
                g->num++;
        }
@@ -316,7 +323,7 @@ static int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
        assert(g->num_chunks);
        fc->current_slice_num = 0;
        if (g->num == 0)
-               set_slice_duration(fc, g);
+               set_group_timing(fc, g);
 
        /* setup header slices */
        buf = vsst->header_buf;
@@ -354,14 +361,6 @@ static int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
                g->first_chunk + g->num_chunks - 1,
                g->num_header_slices, data_slices
        );
-       /* set group start */
-       if (g->num != 0 && vsst->header_len != 0 && fc->first_stream_chunk == 0)
-               /* chunk #0 is the audio file header */
-               tv_scale(g->first_chunk - 1, chunk_tv, &tmp);
-       else
-               tv_scale(g->first_chunk - fc->first_stream_chunk,
-                       chunk_tv, &tmp);
-       tv_add(&fc->stream_start, &tmp, &g->start);
        return 1;
 }