[FFmpeg-devel] [PATCH] avisynth: more intelligent RGB flipping

[Stephen Hutchinson]

On 6/9/20 7:56 PM, Stephen Hutchinson wrote:
> avs_is_color_space provides a generic way of checking whether the
> video is RGB, and has been available since 2.6. This means that
> GetProcAddress doesn't have to run on every frame.
> ---
> Also should probably be applied to the 4.3 branch as well.
> 
>   libavformat/avisynth.c | 27 +++++----------------------
>   1 file changed, 5 insertions(+), 22 deletions(-)
> 
> diff --git a/libavformat/avisynth.c b/libavformat/avisynth.c
> index 2c08ace8db..f029a0e842 100644
> --- a/libavformat/avisynth.c
> +++ b/libavformat/avisynth.c
> @@ -57,6 +57,7 @@ typedef struct AviSynthLibrary {
>       AVSC_DECLARE_FUNC(avs_get_version);
>       AVSC_DECLARE_FUNC(avs_get_video_info);
>       AVSC_DECLARE_FUNC(avs_invoke);
> +    AVSC_DECLARE_FUNC(avs_is_color_space);
>       AVSC_DECLARE_FUNC(avs_release_clip);
>       AVSC_DECLARE_FUNC(avs_release_value);
>       AVSC_DECLARE_FUNC(avs_release_video_frame);
> @@ -133,6 +134,7 @@ static av_cold int avisynth_load_library(void)
>       LOAD_AVS_FUNC(avs_get_version, 0);
>       LOAD_AVS_FUNC(avs_get_video_info, 0);
>       LOAD_AVS_FUNC(avs_invoke, 0);
> +    LOAD_AVS_FUNC(avs_is_color_space, 0);
>       LOAD_AVS_FUNC(avs_release_clip, 0);
>       LOAD_AVS_FUNC(avs_release_value, 0);
>       LOAD_AVS_FUNC(avs_release_video_frame, 0);
> @@ -628,7 +630,6 @@ static int avisynth_read_packet_video(AVFormatContext *s, AVPacket *pkt,
>       const unsigned char *src_p;
>       int n, i, plane, rowsize, planeheight, pitch, bits, ret;
>       const char *error;
> -    int avsplus av_unused;
>   
>       if (avs->curr_frame >= avs->vi->num_frames)
>           return AVERROR_EOF;
> @@ -638,19 +639,6 @@ static int avisynth_read_packet_video(AVFormatContext *s, AVPacket *pkt,
>       if (discard)
>           return 0;
>   
> -#ifdef _WIN32
> -    /* Detect whether we're using AviSynth 2.6 or AviSynth+ by
> -     * looking for whether avs_is_planar_rgb exists. */
> -    if (GetProcAddress(avs_library.library, "avs_is_planar_rgb") == NULL)
> -        avsplus = 0;
> -    else
> -        avsplus = 1;
> -#else
> -    /* AviSynth+ is now the only variant of AviSynth we support
> -     * on Linux and macOS. */
> -    avsplus = 1;
> -#endif
> -
>       bits = avs_library.avs_bits_per_pixel(avs->vi);
>   
>       /* Without the cast to int64_t, calculation overflows at about 9k x 9k
> @@ -687,14 +675,9 @@ static int avisynth_read_packet_video(AVFormatContext *s, AVPacket *pkt,
>           planeheight = avs_library.avs_get_height_p(frame, plane);
>   
>           /* Flip RGB video. */
> -        if (avs_is_rgb24(avs->vi) || avs_is_rgb(avs->vi)) {
> -            src_p = src_p + (planeheight - 1) * pitch;
> -            pitch = -pitch;
> -        }
> -
> -        /* Flip Planar RGB video */
> -        if (avsplus && (avs_library.avs_is_planar_rgb(avs->vi) ||
> -                        avs_library.avs_is_planar_rgba(avs->vi))) {
> +        if (avs_library.avs_is_color_space(avs->vi, AVS_CS_BGR)   ||
> +            avs_library.avs_is_color_space(avs->vi, AVS_CS_BGR48) ||
> +            avs_library.avs_is_color_space(avs->vi, AVS_CS_BGR64)) {
>               src_p = src_p + (planeheight - 1) * pitch;
>               pitch = -pitch;
>           }
> 

Ping.