shithub: dav1d

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cli: Implement line buffering in print_stats()

Console output is incredibly slow on Windows, which is aggravated by
the lack of line buffering. As a result, a significant percentage of
overall runtime is actually spent displaying the decoding progress.

Doing the line buffering manually alleviates most of the issue.

--- a/tools/dav1d.c

+++ b/tools/dav1d.c

@@ -113,18 +113,24 @@

 static void print_stats(const int istty, const unsigned n, const unsigned num,

                         const uint64_t elapsed, const double i_fps)

 {

-    if (istty) fputs("\r", stderr);

-    const double d_fps = 1e9 * n / elapsed;

-    const double speed = d_fps / i_fps;

-    if (num == 0xFFFFFFFF) {

-        fprintf(stderr, "Decoded %u frames", n);

-    } else {

-        fprintf(stderr, "Decoded %u/%u frames (%.1lf%%)", n, num,

-                100.0 * n / num);

+    char buf[80], *b = buf, *const end = buf + 80;

+

+    if (istty)

+        *b++ = '\r';

+    if (num == 0xFFFFFFFF)

+        b += snprintf(b, end - b, "Decoded %u frames", n);

+    else

+        b += snprintf(b, end - b, "Decoded %u/%u frames (%.1lf%%)",

+                      n, num, 100.0 * n / num);

+    if (i_fps && b < end) {

+        const double d_fps = 1e9 * n / elapsed;

+        const double speed = d_fps / i_fps;

+        b += snprintf(b, end - b, " - %.2lf/%.2lf fps (%.2lfx)",

+                      d_fps, i_fps, speed);

     }

-    if (i_fps)

-        fprintf(stderr, " - %.2lf/%.2lf fps (%.2lfx)", d_fps, i_fps, speed);

-    if (!istty) fputs("\n", stderr);

+    if (!istty)

+        strcpy(b > end - 2 ? end - 2 : b, "\n");

+    fputs(buf, stderr);

 }

 int main(const int argc, char *const *const argv) {