On 08/18/2014 11:12 AM, Christophe Gisquet wrote:
The raw coded bits are extracted prior to decorrelation, as is correctly
performed by the decoder, and not after.

Fixes ticket #2768.
---
  libavcodec/alacenc.c | 16 ++++++++++++++--
  1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/libavcodec/alacenc.c b/libavcodec/alacenc.c
index c8354d2..e62c015 100644
--- a/libavcodec/alacenc.c
+++ b/libavcodec/alacenc.c
@@ -394,6 +394,19 @@ static void write_element(AlacEncodeContext *s,
          init_sample_buffers(s, channels, samples);
          write_element_header(s, element, instance);
+ // extract extra bits if needed
+        if (s->extra_bits) {
+            uint32_t mask = (1 << s->extra_bits) - 1;
+            for (j = 0; j < channels; j++) {
+                int32_t *extra = s->predictor_buf[j];
+                int32_t *smp   = s->sample_buf[j];
+                for (i = 0; i < s->frame_size; i++) {
+                    extra[i] = smp[i] & mask;
+                    smp[i] >>= s->extra_bits;
+                }
+            }
+        }
+
          if (channels == 2)
              alac_stereo_decorrelation(s);
          else
@@ -419,8 +432,7 @@ static void write_element(AlacEncodeContext *s,
              uint32_t mask = (1 << s->extra_bits) - 1;
              for (i = 0; i < s->frame_size; i++) {
                  for (j = 0; j < channels; j++) {
-                    put_bits(pb, s->extra_bits, s->sample_buf[j][i] & mask);
-                    s->sample_buf[j][i] >>= s->extra_bits;
+                    put_bits(pb, s->extra_bits, s->predictor_buf[j][i] & mask);
                  }
              }
          }

Masking the value when writing should be unnecessary since it is already masked out above.

Thanks,
Justin

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