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

[Michael Niedermayer]

On Fri, Jul 20, 2018 at 09:51:49AM +0200, Tobias Rapp wrote:
> On 19.07.2018 23:37, Michael Niedermayer wrote:
> >On Thu, Jul 19, 2018 at 01:53:09PM +0200, Tobias Rapp wrote:
> >>On 18.07.2018 19:31, Marcin Gorzel wrote:
> >>>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.
> >>>---
> >>>  libswresample/rematrix.c          | 6 ++++--
> >>>  libswresample/x86/rematrix_init.c | 6 ++++--
> >>>  2 files changed, 8 insertions(+), 4 deletions(-)
> >>>
> >>>diff --git a/libswresample/rematrix.c b/libswresample/rematrix.c
> >>>index 8227730056..d1a0cfe7f8 100644
> >>>--- a/libswresample/rematrix.c
> >>>+++ b/libswresample/rematrix.c
> >>>@@ -384,8 +384,10 @@ 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_count > 0) ? s->in.ch_count :
> >>>+        av_get_channel_layout_nb_channels(s->in_ch_layout);
> >>>+    int nb_out = (s->out.ch_count > 0) ? s->out.ch_count :
> >>>+        av_get_channel_layout_nb_channels(s->out_ch_layout);
> >>>      s->mix_any_f = NULL;
> >>>diff --git a/libswresample/x86/rematrix_init.c b/libswresample/x86/rematrix_init.c
> >>>index d71b41a73e..4f9c92e4ab 100644
> >>>--- a/libswresample/x86/rematrix_init.c
> >>>+++ b/libswresample/x86/rematrix_init.c
> >>>@@ -33,8 +33,10 @@ 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_count > 0) ? s->in.ch_count :
> >>>+        av_get_channel_layout_nb_channels(s->in_ch_layout);
> >>>+    int nb_out = (s->out.ch_count > 0) ? s->out.ch_count :
> >>>+        av_get_channel_layout_nb_channels(s->out_ch_layout);
> >>>      int num    = nb_in * nb_out;
> >>>      int i,j;
> >>>
> >>
> >>Patch looks good to me, except that the title should be updated to reflect
> >>the new logic. I suggest something like "swresample: Use channel count for
> >>rematrix initialization if defined".
> >
> >The patch does not look good to me
> >There should be a field that represents the count of channels.
> >No conditional should be needed
> >
> >please check that every field is wrong in at least some case.
> >If true a new field must be added or a existing one needs to be set
> >differently
> >But there should be a field that represents the channel count.
> 
> If I understand correctly you say that the fall-back to
> av_get_channel_layout_nb_channels() is not needed here as both functions are
> internal and called only as part of swr_init() so we may safely assume that
> the in/out.ch_count fields have been initialized before this code is
> reached.

yes, if that is tested and works. If it does not work, it would be very
interresting why not


> 
> Fine with me. Marcin, would you update the patch once more? And there are
> some additional FATE tests for the pan filter that I can post once this
> patch is through, if you haven't made up your own tests.
> 
> Regards,
> Tobias
> 
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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

"I am not trying to be anyone's saviour, I'm trying to think about the
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