swresample/resample: optimize exact_rational=on:linear_interp=on case

separate dsp.resample to dsp.resample_common and dsp.resample_linear
and choose to call faster resample_common even when linear_interp=on
when c->frac and c->dst_incr_mod are both zero

speed up resampling when exact_rational and linear_interp are both
enabled because exact_rational force c->frac and c->dst_incr_mod to
be zero when soft compensation does not happen

benchmark on exact_rational=on:linear_interp=on
        old     new
real    8.432s  5.097s
user    7.679s  4.989s
sys     0.125s  0.107s

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Muhammad Faiz <mfcc64@gmail.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/libswresample/resample.h b/libswresample/resample.h
index 7fe9b97f7f..946f5cc8e3 100644
--- a/libswresample/resample.h
+++ b/libswresample/resample.h
@@ -53,8 +53,10 @@ typedef struct ResampleContext {
     struct {
         void (*resample_one)(void *dst, const void *src,
                              int n, int64_t index, int64_t incr);
-        int (*resample)(struct ResampleContext *c, void *dst,
-                        const void *src, int n, int update_ctx);
+        int (*resample_common)(struct ResampleContext *c, void *dst,
+                               const void *src, int n, int update_ctx);
+        int (*resample_linear)(struct ResampleContext *c, void *dst,
+                               const void *src, int n, int update_ctx);
     } dsp;
 } ResampleContext;