[FFmpeg-devel] [PATCH]lavc/libx264: Support monochrome encoding

[James Almer]

On 8/7/2018 3:25 PM, Carl Eugen Hoyos wrote:
> Hi!
> 
> Attached patch allows monochrome encoding with libx264, supported in
> master since a few hours.
> 
> Please comment, Carl Eugen
> 
> 
> 0001-lavc-libx264-Support-monochrome-encoding.patch
> 
> 
> From a26245de63bdc9afc6b21ea6e97b95a2a7e1e765 Mon Sep 17 00:00:00 2001
> From: Carl Eugen Hoyos <ceffmpeg at gmail.com>
> Date: Tue, 7 Aug 2018 20:23:06 +0200
> Subject: [PATCH] lavc/libx264: Support monochrome encoding.
> 
> ---
>  libavcodec/libx264.c |   14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
> index 12379ff..cc9e5c8 100644
> --- a/libavcodec/libx264.c
> +++ b/libavcodec/libx264.c
> @@ -443,6 +443,10 @@ static int convert_pix_fmt(enum AVPixelFormat pix_fmt)
>  #ifdef X264_CSP_NV21
>      case AV_PIX_FMT_NV21:      return X264_CSP_NV21;
>  #endif
> +#ifdef X264_CSP_I400
> +    case AV_PIX_FMT_GRAY8:
> +    case AV_PIX_FMT_GRAY10:    return X264_CSP_I400;
> +#endif
>      };
>      return 0;
>  }
> @@ -855,6 +859,9 @@ static const enum AVPixelFormat pix_fmts_8bit[] = {
>  #ifdef X264_CSP_NV21
>      AV_PIX_FMT_NV21,
>  #endif
> +#ifdef X264_CSP_I400
> +    AV_PIX_FMT_GRAY8,
> +#endif

Unneeded. This array is only used with old x264 builds.

>      AV_PIX_FMT_NONE
>  };
>  static const enum AVPixelFormat pix_fmts_9bit[] = {
> @@ -867,6 +874,9 @@ static const enum AVPixelFormat pix_fmts_10bit[] = {
>      AV_PIX_FMT_YUV422P10,
>      AV_PIX_FMT_YUV444P10,
>      AV_PIX_FMT_NV20,
> +#ifdef X264_CSP_I400
> +    AV_PIX_FMT_GRAY10,
> +#endif
>      AV_PIX_FMT_NONE
>  };

Same.

>  static const enum AVPixelFormat pix_fmts_all[] = {
> @@ -885,6 +895,10 @@ static const enum AVPixelFormat pix_fmts_all[] = {
>      AV_PIX_FMT_YUV422P10,
>      AV_PIX_FMT_YUV444P10,
>      AV_PIX_FMT_NV20,
> +#ifdef X264_CSP_I400
> +    AV_PIX_FMT_GRAY8,
> +    AV_PIX_FMT_GRAY10,
> +#endif
>      AV_PIX_FMT_NONE
>  };
>  #if CONFIG_LIBX264RGB_ENCODER
> -- 1.7.10.4

I think you need to add these two pixfmts to avfmt2_num_planes() as
well, so they may return 1 instead of the default 3.

It seems to work, so should be ok otherwise.