video/filter: add vf_buffer

Mostly useful for debugging.

DOCS/man/vf.rst

@@ -969,3 +969,9 @@ Available filters are:
             Use default VDPAU scaling (default).
         1-9
             Apply high quality VDPAU scaling (needs capable hardware).
+
+``buffer=<num>``
+    Buffer ``<num>`` frames in the filter chain. This filter is probably pretty
+    useless, except for debugging. (Note that this won't help smoothing out
+    latencies with decoding, because the filter will never output a frame if
+    the buffer isn't full, except on EOF.)

old-makefile

@@ -247,6 +247,7 @@ SOURCES = audio/audio.c \
           video/decode/vd_lavc.c \
           video/filter/vf.c \
           video/filter/pullup.c \
+          video/filter/vf_buffer.c \
           video/filter/vf_crop.c \
           video/filter/vf_delogo.c \
           video/filter/vf_divtc.c \

video/filter/vf.c

@@ -72,6 +72,7 @@ extern const vf_info_t vf_info_lavfi;
 extern const vf_info_t vf_info_vaapi;
 extern const vf_info_t vf_info_vapoursynth;
 extern const vf_info_t vf_info_vdpaupp;
+extern const vf_info_t vf_info_buffer;
 
 // list of available filters:
 static const vf_info_t *const filter_list[] = {
@@ -109,6 +110,7 @@ static const vf_info_t *const filter_list[] = {
     &vf_info_sub,
     &vf_info_yadif,
     &vf_info_stereo3d,
+    &vf_info_buffer,
 #if HAVE_DLOPEN
     &vf_info_dlopen,
 #endif

video/filter/vf_buffer.c

@@ -0,0 +1,93 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include "talloc.h"
+
+#include "options/m_option.h"
+
+#include "video/img_format.h"
+#include "video/mp_image.h"
+
+#include "vf.h"
+
+#define MAX_Q 100
+
+struct vf_priv_s {
+    struct mp_image *queued[MAX_Q];
+    int num_queued;
+    int cfg_num;
+};
+
+static void flush(struct vf_instance *vf)
+{
+    for (int n = 0; n < vf->priv->num_queued; n++)
+        mp_image_unrefp(&vf->priv->queued[n]);
+    vf->priv->num_queued = 0;
+}
+
+static int config(struct vf_instance *vf,
+                  int width, int height, int d_width, int d_height,
+                  unsigned int flags, unsigned int outfmt)
+{
+    flush(vf);
+    return vf_next_config(vf,width,height,d_width,d_height,flags,outfmt);
+}
+
+static int filter_ext(struct vf_instance *vf, struct mp_image *mpi)
+{
+    struct vf_priv_s *p = vf->priv;
+    if (mpi) {
+        if (p->num_queued == p->cfg_num) {
+            vf_add_output_frame(vf, p->queued[p->num_queued - 1]);
+            p->num_queued--;
+        }
+        p->num_queued++;
+        for (int n = p->num_queued - 1; n > 0; n--)
+            p->queued[n] = p->queued[n - 1];
+        p->queued[0] = mpi;
+    } else {
+        // EOF
+        while (p->num_queued) {
+            vf_add_output_frame(vf, p->queued[p->num_queued - 1]);
+            p->num_queued--;
+        }
+    }
+    return 0;
+}
+
+static int control(vf_instance_t *vf, int request, void *data)
+{
+    if (request == VFCTRL_SEEK_RESET) {
+        flush(vf);
+        return CONTROL_OK;
+    }
+    return CONTROL_UNKNOWN;
+}
+
+static void uninit(vf_instance_t *vf)
+{
+    flush(vf);
+}
+
+static int vf_open(vf_instance_t *vf)
+{
+    vf->config = config;
+    vf->filter_ext = filter_ext;
+    vf->control = control;
+    vf->uninit = uninit;
+    return 1;
+}
+
+#define OPT_BASE_STRUCT struct vf_priv_s
+const vf_info_t vf_info_buffer = {
+    .description = "buffer a number of frames",
+    .name = "buffer",
+    .open = vf_open,
+    .priv_size = sizeof(struct vf_priv_s),
+    .options = (const struct m_option[]){
+        OPT_INTRANGE("num", cfg_num, 0, 1, MAX_Q, OPTDEF_INT(2)),
+        {0}
+    },
+};

wscript_build.py

@@ -302,6 +302,7 @@ def build(ctx):
         ( "video/decode/vdpau.c",                "vdpau-hwaccel" ),
         ( "video/filter/pullup.c" ),
         ( "video/filter/vf.c" ),
+        ( "video/filter/vf_buffer.c" ),
         ( "video/filter/vf_crop.c" ),
         ( "video/filter/vf_delogo.c" ),
         ( "video/filter/vf_divtc.c" ),