Allow substitution of channel pairs in the input for nearby channel pairs in
the output in order to get a closer match. Also weigh LFE channel mismatch
differently to favor matching the same layout without LFE over one less
channel with LFE.
---
Update patch avoids channel substitution when the substituted channels are
also contained in the input. Also reordered the priority in the substitution
list to choose the closest pair and to use single-channel replacement as the
lowest priority.
libavfilter/avfiltergraph.c | 83 +++++++++++++++++++++++++++++++++++++------
1 files changed, 72 insertions(+), 11 deletions(-)
diff --git a/libavfilter/avfiltergraph.c b/libavfilter/avfiltergraph.c
index c147c3b..a0aa807 100644
--- a/libavfilter/avfiltergraph.c
+++ b/libavfilter/avfiltergraph.c
@@ -424,11 +424,44 @@ static void swap_samplerates(AVFilterGraph *graph)
swap_samplerates_on_filter(graph->filters[i]);
}
+#define CH_CENTER_PAIR (AV_CH_FRONT_LEFT_OF_CENTER |
AV_CH_FRONT_RIGHT_OF_CENTER)
+#define CH_FRONT_PAIR (AV_CH_FRONT_LEFT | AV_CH_FRONT_RIGHT)
+#define CH_STEREO_PAIR (AV_CH_STEREO_LEFT | AV_CH_STEREO_RIGHT)
+#define CH_WIDE_PAIR (AV_CH_WIDE_LEFT | AV_CH_WIDE_RIGHT)
+#define CH_SIDE_PAIR (AV_CH_SIDE_LEFT | AV_CH_SIDE_RIGHT)
+#define CH_DIRECT_PAIR (AV_CH_SURROUND_DIRECT_LEFT |
AV_CH_SURROUND_DIRECT_RIGHT)
+#define CH_BACK_PAIR (AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT)
+
+/* allowable substitutions for channel pairs when comparing layouts,
+ * ordered by priority for both values */
+static const uint64_t ch_subst[][2] = {
+ { CH_FRONT_PAIR, CH_CENTER_PAIR },
+ { CH_FRONT_PAIR, CH_WIDE_PAIR },
+ { CH_FRONT_PAIR, AV_CH_FRONT_CENTER },
+ { CH_CENTER_PAIR, CH_FRONT_PAIR },
+ { CH_CENTER_PAIR, CH_WIDE_PAIR },
+ { CH_CENTER_PAIR, AV_CH_FRONT_CENTER },
+ { CH_WIDE_PAIR, CH_FRONT_PAIR },
+ { CH_WIDE_PAIR, CH_CENTER_PAIR },
+ { CH_WIDE_PAIR, AV_CH_FRONT_CENTER },
+ { AV_CH_FRONT_CENTER, CH_FRONT_PAIR },
+ { AV_CH_FRONT_CENTER, CH_CENTER_PAIR },
+ { AV_CH_FRONT_CENTER, CH_WIDE_PAIR },
+ { CH_SIDE_PAIR, CH_DIRECT_PAIR },
+ { CH_SIDE_PAIR, CH_BACK_PAIR },
+ { CH_SIDE_PAIR, AV_CH_BACK_CENTER },
+ { CH_BACK_PAIR, CH_DIRECT_PAIR },
+ { CH_BACK_PAIR, CH_SIDE_PAIR },
+ { CH_BACK_PAIR, AV_CH_BACK_CENTER },
+ { AV_CH_BACK_CENTER, CH_BACK_PAIR },
+ { AV_CH_BACK_CENTER, CH_DIRECT_PAIR },
+ { AV_CH_BACK_CENTER, CH_SIDE_PAIR },
+};
+
static void swap_channel_layouts_on_filter(AVFilterContext *filter)
{
AVFilterLink *link = NULL;
- uint64_t chlayout;
- int i, j;
+ int i, j, k;
for (i = 0; i < filter->nb_inputs; i++) {
link = filter->inputs[i];
@@ -440,27 +473,55 @@ static void
swap_channel_layouts_on_filter(AVFilterContext *filter)
if (i == filter->nb_inputs)
return;
- chlayout = link->out_channel_layouts->channel_layouts[0];
-
for (i = 0; i < filter->nb_outputs; i++) {
AVFilterLink *outlink = filter->outputs[i];
- int best_idx, best_score = INT_MIN;
+ int best_idx, best_score = INT_MIN, best_count_diff = INT_MAX;
if (outlink->type != AVMEDIA_TYPE_AUDIO ||
outlink->in_channel_layouts->nb_channel_layouts < 2)
continue;
for (j = 0; j < outlink->in_channel_layouts->nb_channel_layouts; j++) {
+ uint64_t in_chlayout =
link->out_channel_layouts->channel_layouts[0];
uint64_t out_chlayout =
outlink->in_channel_layouts->channel_layouts[j];
- int matched_channels = av_get_channel_layout_nb_channels(chlayout
&
-
out_chlayout);
- int extra_channels =
av_get_channel_layout_nb_channels(out_chlayout &
-
(~chlayout));
- int score = matched_channels - extra_channels;
+ int in_channels =
av_get_channel_layout_nb_channels(in_chlayout);
+ int out_channels =
av_get_channel_layout_nb_channels(out_chlayout);
+ int count_diff = out_channels - in_channels;
+ int matched_channels, extra_channels;
+ int score = 0;
+
+ /* channel substitution */
+ for (k = 0; k < FF_ARRAY_ELEMS(ch_subst); k++) {
+ uint64_t cmp0 = ch_subst[k][0];
+ uint64_t cmp1 = ch_subst[k][1];
+ if (( in_chlayout & cmp0) && (!(out_chlayout & cmp0)) &&
+ (out_chlayout & cmp1) && (!( in_chlayout & cmp1))) {
+ in_chlayout &= ~cmp0;
+ out_chlayout &= ~cmp1;
+ /* add score for channel match, minus a deduction for
+ having to do the substitution */
+ score += 10 * av_get_channel_layout_nb_channels(cmp1) - 2;
+ }
+ }
- if (score > best_score) {
+ /* no penalty for LFE channel mismatch */
+ if ( (in_chlayout & AV_CH_LOW_FREQUENCY) &&
+ (out_chlayout & AV_CH_LOW_FREQUENCY))
+ score += 10;
+ in_chlayout &= ~AV_CH_LOW_FREQUENCY;
+ out_chlayout &= ~AV_CH_LOW_FREQUENCY;
+
+ matched_channels = av_get_channel_layout_nb_channels(in_chlayout &
+ out_chlayout);
+ extra_channels = av_get_channel_layout_nb_channels(out_chlayout &
+
(~in_chlayout));
+ score += 10 * matched_channels - 5 * extra_channels;
+
+ if (score > best_score ||
+ (count_diff < best_count_diff && score == best_score)) {
best_score = score;
best_idx = j;
+ best_count_diff = count_diff;
}
}
FFSWAP(uint64_t, outlink->in_channel_layouts->channel_layouts[0],
--
1.7.1
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