avcodec/flacenc: Avoid shift where possible

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/flacenc.c

@@ -525,11 +525,10 @@ static void copy_samples(FlacEncodeContext *s, const void *samples)
 {
     int i, j, ch;
     FlacFrame *frame;
-    int shift = av_get_bytes_per_sample(s->avctx->sample_fmt) * 8 -
-                s->avctx->bits_per_raw_sample;
 
-#define COPY_SAMPLES(bits) do {                                     \
+#define COPY_SAMPLES(bits, shift0) do {                             \
     const int ## bits ## _t *samples0 = samples;                    \
+    const int shift = shift0;                                       \
     frame = &s->frame;                                              \
     for (i = 0, j = 0; i < frame->blocksize; i++)                   \
         for (ch = 0; ch < s->channels; ch++, j++)                   \
@@ -537,9 +536,9 @@ static void copy_samples(FlacEncodeContext *s, const void *samples)
 } while (0)
 
     if (s->avctx->sample_fmt == AV_SAMPLE_FMT_S16)
-        COPY_SAMPLES(16);
+        COPY_SAMPLES(16, 0);
     else
-        COPY_SAMPLES(32);
+        COPY_SAMPLES(32, 32 - s->avctx->bits_per_raw_sample);
 }