@@ -52,6 +52,7 @@ enum var_name {

 typedef struct LUT2Context {

     const AVClass *class;

+    FFFrameSync fs;

     char   *comp_expr_str[4];

@@ -66,7 +67,6 @@ typedef struct LUT2Context {

     void (*lut2)(struct LUT2Context *s, AVFrame *dst, AVFrame *srcx, AVFrame *srcy);

-    FFFrameSync fs;

 } LUT2Context;

 #define OFFSET(x) offsetof(LUT2Context, x)

@@ -85,6 +85,7 @@ static av_cold void uninit(AVFilterContext *ctx)

     LUT2Context *s = ctx->priv;

     int i;

+    ff_framesync2_uninit(&s->fs);

     av_frame_free(&s->prev_frame);

     for (i = 0; i < 4; i++) {

@@ -212,14 +213,14 @@ static int process_frame(FFFrameSync *fs)

     AVFilterContext *ctx = fs->parent;

     LUT2Context *s = fs->opaque;

     AVFilterLink *outlink = ctx->outputs[0];

-    AVFrame *out, *srcx, *srcy;

+    AVFrame *out, *srcx = NULL, *srcy = NULL;

     int ret;

     if ((ret = ff_framesync2_get_frame(&s->fs, 0, &srcx, 0)) < 0 ||

         (ret = ff_framesync2_get_frame(&s->fs, 1, &srcy, 0)) < 0)

         return ret;

-    if (ctx->is_disabled) {

+    if (ctx->is_disabled || !srcy) {

         out = av_frame_clone(srcx);

         if (!out)

             return AVERROR(ENOMEM);

@@ -332,7 +333,7 @@ static int lut2_config_output(AVFilterLink *outlink)

     in = s->fs.in;

     in[0].time_base = srcx->time_base;

     in[1].time_base = srcy->time_base;

-    in[0].sync   = 1;

+    in[0].sync   = 2;

     in[0].before = EXT_STOP;

     in[0].after  = EXT_INFINITY;

     in[1].sync   = 1;

@@ -378,11 +379,12 @@ static const AVFilterPad outputs[] = {

 #define lut2_options options

-AVFILTER_DEFINE_CLASS(lut2);

+FRAMESYNC_DEFINE_CLASS(lut2, LUT2Context, fs);

 AVFilter ff_vf_lut2 = {

     .name          = "lut2",

     .description   = NULL_IF_CONFIG_SMALL("Compute and apply a lookup table from two video inputs."),

+    .preinit       = lut2_framesync_preinit,

     .priv_size     = sizeof(LUT2Context),

     .priv_class    = &lut2_class,

     .uninit        = uninit,