return 1;
}
+/**
+ * Perform one round of query_formats() and merging formats lists on the
+ * filter graph.
+ * @return >=0 if all links formats lists could be queried and merged;
+ * AVERROR(EAGAIN) some progress was made in the queries or merging
+ * and a later call may succeed;
+ * AVERROR(EIO) (may be changed) plus a log message if no progress
+ * was made and the negotiation is stuck;
+ * a negative error code if some other error happened
+ */
static int query_formats(AVFilterGraph *graph, AVClass *log_ctx)
{
int i, j, ret;
int scaler_count = 0, resampler_count = 0;
- int count_queried = 0, count_merged = 0, count_already_merged = 0,
- count_delayed = 0;
+ int count_queried = 0; /* successful calls to query_formats() */
+ int count_merged = 0; /* successful merge of formats lists */
+ int count_already_merged = 0; /* lists already merged */
+ int count_delayed = 0; /* lists that need to be merged later */
for (i = 0; i < graph->nb_filters; i++) {
AVFilterContext *f = graph->filters[i];
ret = ff_default_query_formats(f);
if (ret < 0 && ret != AVERROR(EAGAIN))
return ret;
- count_queried++;
+ /* note: EAGAIN could indicate a partial success, not counted yet */
+ count_queried += ret >= 0;
}
/* go through and merge as many format lists as possible */
if (count_delayed) {
AVBPrint bp;
+ /* if count_queried > 0, one filter at least did set its formats,
+ that will give additional information to its neighbour;
+ if count_merged > 0, one pair of formats lists at least was merged,
+ that will give additional information to all connected filters;
+ in both cases, progress was made and a new round must be done */
if (count_queried || count_merged)
return AVERROR(EAGAIN);
av_bprint_init(&bp, 0, AV_BPRINT_SIZE_AUTOMATIC);