avfilter: add showfreqs filter

1 files changed, 26 insertions, 0 deletions

diff --git a/libavutil/fifo.c b/libavutil/fifo.c
index f2fe93de75..07fb4ec811 100644
--- a/libavutil/fifo.c
+++ b/libavutil/fifo.c
@@ -148,6 +148,32 @@ int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size,
     return total - size;
 }
 
+int av_fifo_generic_peek(AVFifoBuffer *f, void *dest, int buf_size,
+                         void (*func)(void *, void *, int))
+{
+// Read memory barrier needed for SMP here in theory
+    uint8_t *rptr = f->rptr;
+    uint32_t rndx = f->rndx;
+
+    do {
+        int len = FFMIN(f->end - f->rptr, buf_size);
+        if (func)
+            func(dest, f->rptr, len);
+        else {
+            memcpy(dest, f->rptr, len);
+            dest = (uint8_t *)dest + len;
+        }
+// memory barrier needed for SMP here in theory
+        av_fifo_drain(f, len);
+        buf_size -= len;
+    } while (buf_size > 0);
+
+    f->rptr = rptr;
+    f->rndx = rndx;
+
+    return 0;
+}
+
 int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size,
                          void (*func)(void *, void *, int))
 {