[FFmpeg-devel] [PATCH] libswresample: Use channel count if channel layout is undefined

[Marcin Gorzel]

Rematrixing supports up to 64 channels. However, there is only a limited number of channel layouts defined. Since the in/out channel count is obtained from the channel layout, for undefined layouts (e.g. for 9, 10, 11 channels etc.) the rematrixing fails.

In ticket #6790 the problem has been partially addressed by applying a patch to swr_set_matrix() in rematrix.c:72.
However, a similar change must be also applied to swri_rematrix_init() in rematrix.c:389 and swri_rematrix_init_x86() in rematrix_init.c:36.

This patch adds the following check to the swri_rematrix_init() in rematrix.c:389 and swri_rematrix_init_x86() in rematrix_init.c:36: if channel layout is non-zero, obtain channel count from the channel layout, otherwise, use channel count instead.

It also modifies the checks in swr_set_matrix() in rematrix.c:72 to match the above checks. (Since av_get_channel_layout_nb_channels(s->user_in_ch_layout) was originally used, there may be preference to rely on the channel layout first (if available) before falling back to the user channel count).
---
 libswresample/rematrix.c          | 18 ++++++++++++------
 libswresample/x86/rematrix_init.c |  8 ++++++--
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/libswresample/rematrix.c b/libswresample/rematrix.c
index 8227730056..8c9fbf3804 100644
--- a/libswresample/rematrix.c
+++ b/libswresample/rematrix.c
@@ -69,10 +69,12 @@ int swr_set_matrix(struct SwrContext *s, const double *matrix, int stride)
         return AVERROR(EINVAL);
     memset(s->matrix, 0, sizeof(s->matrix));
     memset(s->matrix_flt, 0, sizeof(s->matrix_flt));
-    nb_in = (s->user_in_ch_count > 0) ? s->user_in_ch_count :
-        av_get_channel_layout_nb_channels(s->user_in_ch_layout);
-    nb_out = (s->user_out_ch_count > 0) ? s->user_out_ch_count :
-        av_get_channel_layout_nb_channels(s->user_out_ch_layout);
+    nb_in = s->user_in_ch_layout != 0
+        ? av_get_channel_layout_nb_channels(s->user_in_ch_layout)
+        : s->user_in_ch_count;
+    nb_out = s->user_out_ch_layout != 0
+        ? av_get_channel_layout_nb_channels(s->user_out_ch_layout)
+        : s->user_out_ch_count;
     for (out = 0; out < nb_out; out++) {
         for (in = 0; in < nb_in; in++)
             s->matrix_flt[out][in] = s->matrix[out][in] = matrix[in];
@@ -384,8 +386,12 @@ av_cold static int auto_matrix(SwrContext *s)
 
 av_cold int swri_rematrix_init(SwrContext *s){
     int i, j;
-    int nb_in  = av_get_channel_layout_nb_channels(s->in_ch_layout);
-    int nb_out = av_get_channel_layout_nb_channels(s->out_ch_layout);
+    int nb_in  = s->in_ch_layout != 0
+        ? av_get_channel_layout_nb_channels(s->in_ch_layout)
+        : s->user_in_ch_count;
+    int nb_out = s->out_ch_layout != 0
+        ? av_get_channel_layout_nb_channels(s->out_ch_layout)
+        : s->user_out_ch_count;
 
     s->mix_any_f = NULL;
 
diff --git a/libswresample/x86/rematrix_init.c b/libswresample/x86/rematrix_init.c
index d71b41a73e..a6ae074926 100644
--- a/libswresample/x86/rematrix_init.c
+++ b/libswresample/x86/rematrix_init.c
@@ -33,8 +33,12 @@ D(int16, sse2)
 av_cold int swri_rematrix_init_x86(struct SwrContext *s){
 #if HAVE_X86ASM
     int mm_flags = av_get_cpu_flags();
-    int nb_in  = av_get_channel_layout_nb_channels(s->in_ch_layout);
-    int nb_out = av_get_channel_layout_nb_channels(s->out_ch_layout);
+    int nb_in  = s->in_ch_layout != 0
+        ? av_get_channel_layout_nb_channels(s->in_ch_layout)
+        : s->user_in_ch_count;
+    int nb_out = s->out_ch_layout != 0
+        ? av_get_channel_layout_nb_channels(s->out_ch_layout)
+        : s->user_out_ch_count;
     int num    = nb_in * nb_out;
     int i,j;
 
-- 
2.18.0.203.gfac676dfb9-goog