This isn't used by the reference encoder, but it is supported by the decoder.
---
I verified that the resulting files using prediction_type == 15
play correctly in QuickTime.
libavcodec/alacenc.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/libavcodec/alacenc.c b/libavcodec/alacenc.c
index e7977b3..89d8e09 100644
--- a/libavcodec/alacenc.c
+++ b/libavcodec/alacenc.c
@@ -348,6 +348,7 @@ static void alac_entropy_coder(AlacEncodeContext *s)
static void write_compressed_frame(AlacEncodeContext *s)
{
int i, j;
+ int prediction_type = 0;
if (s->avctx->channels == 2)
alac_stereo_decorrelation(s);
@@ -358,7 +359,7 @@ static void write_compressed_frame(AlacEncodeContext *s)
calc_predictor_params(s, i);
- put_bits(&s->pbctx, 4, 0); // prediction type : currently only type 0
has been RE'd
+ put_bits(&s->pbctx, 4, prediction_type);
put_bits(&s->pbctx, 4, s->lpc[i].lpc_quant);
put_bits(&s->pbctx, 3, s->rc.rice_modifier);
@@ -373,6 +374,14 @@ static void write_compressed_frame(AlacEncodeContext *s)
for (i = 0; i < s->avctx->channels; i++) {
alac_linear_predictor(s, i);
+
+ // TODO: determine when this will actually help. for now it's not used.
+ if (prediction_type == 15) {
+ // 2nd pass 1st order filter
+ for (j = s->avctx->frame_size - 1; j > 0; j--)
+ s->predictor_buf[j] -= s->predictor_buf[j - 1];
+ }
+
alac_entropy_coder(s);
}
}
--
1.7.1
_______________________________________________
libav-devel mailing list
[email protected]
https://lists.libav.org/mailman/listinfo/libav-devel
