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

[Tobias Rapp]

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".

If nobody objects within the next days I will amend the title, push the 
patch to master and backport the fix to release branches.

Regards,
Tobias