From aa264da5bf6a3d82a47abba4cfcfa629dd1f3daa Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Tue, 4 Sep 2012 14:02:30 +0300
Subject: [PATCH] adpcmenc: Calculate the IMA_QT predictor without overflow
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Previously, the value given to put_bits was 10 bits long for positive
predictors, even though 9 bits were to be written. The extra bit could
in some cases overwrite existing bits in the bitstream writer cache.
This fixes a failed assert in put_bits.h, when running a version
built with -DDEBUG.
The fate test result gets slightly improved, thanks to getting rid
of the overwritten bits in the bitstream writer cache.
Signed-off-by: Martin Storsjö <martin@martin.st>
---
libavcodec/adpcmenc.c | 2 +-
tests/ref/fate/acodec-adpcm-ima_qt | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/libavcodec/adpcmenc.c b/libavcodec/adpcmenc.c
index 843b32fae51..f8ecd589dce 100644
--- a/libavcodec/adpcmenc.c
+++ b/libavcodec/adpcmenc.c
@@ -570,7 +570,7 @@ static int adpcm_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
init_put_bits(&pb, dst, pkt_size * 8);
for (ch = 0; ch < avctx->channels; ch++) {
- put_bits(&pb, 9, (c->status[ch].prev_sample + 0x10000) >> 7);
+ put_bits(&pb, 9, (c->status[ch].prev_sample & 0xFFFF) >> 7);
put_bits(&pb, 7, c->status[ch].step_index);
if (avctx->trellis > 0) {
uint8_t buf[64];
diff --git a/tests/ref/fate/acodec-adpcm-ima_qt b/tests/ref/fate/acodec-adpcm-ima_qt
index 79b8c60ccc1..80015275fc2 100644
--- a/tests/ref/fate/acodec-adpcm-ima_qt
+++ b/tests/ref/fate/acodec-adpcm-ima_qt
@@ -1,4 +1,4 @@
-057d27978b35888776512e4e9669a63b *tests/data/fate/acodec-adpcm-ima_qt.aiff
+23cbae1182e150ebf28e0abfb9cba127 *tests/data/fate/acodec-adpcm-ima_qt.aiff
281252 tests/data/fate/acodec-adpcm-ima_qt.aiff
-169c40435c68d50112c9c61fc67e446d *tests/data/fate/acodec-adpcm-ima_qt.out.wav
-stddev: 918.61 PSNR: 37.07 MAXDIFF:34029 bytes: 1058400/ 1058560
+b0fafd002c38fb70acaddfda1a31ed61 *tests/data/fate/acodec-adpcm-ima_qt.out.wav
+stddev: 904.76 PSNR: 37.20 MAXDIFF:34029 bytes: 1058400/ 1058560
--
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