Based on a patch by Stefano Sabatini.
git.videolan.org/ffmpeg.git
commit e280a4da2ae6fd44f0079358ecc5aa08e388a5ed
---
libavcodec/8svx.c | 34 ++++++++++++++++++++++++----------
1 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/libavcodec/8svx.c b/libavcodec/8svx.c
index 4b60377..3155171 100644
--- a/libavcodec/8svx.c
+++ b/libavcodec/8svx.c
@@ -41,6 +41,26 @@ static const int16_t fibonacci[16] = { -34<<8, -21<<8,
-13<<8, -8<<8, -5<<8,
static const int16_t exponential[16] = { -128<<8, -64<<8, -32<<8, -16<<8,
-8<<8, -4<<8, -2<<8, -1<<8,
0, 1<<8, 2<<8, 4<<8, 8<<8, 16<<8,
32<<8, 64<<8 };
+/**
+ * Delta decode the compressed values in src, and put the resulting
+ * decoded samples in dst.
+ */
+static void delta_decode(int16_t *dst, const uint8_t *src, int src_size,
+ int16_t *state, const int16_t *table)
+{
+ int val = *state;
+
+ while (src_size--) {
+ uint8_t d = *src++;
+ val = av_clip_int16(val + table[d & 0xF]);
+ *dst++ = val;
+ val = av_clip_int16(val + table[d >> 4]);
+ *dst++ = val;
+ }
+
+ *state = val;
+}
+
/** decode a frame */
static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int
*data_size,
AVPacket *avpkt)
@@ -56,20 +76,14 @@ static int eightsvx_decode_frame(AVCodecContext *avctx,
void *data, int *data_si
return -1;
if(avctx->frame_number == 0) {
- esc->fib_acc = buf[1] << 8;
- buf_size -= 2;
- buf += 2;
+ esc->fib_acc = buf[0] << 8;
+ buf_size -= 1;
+ buf += 1;
}
*data_size = buf_size << 2;
- while(buf < buf_end) {
- uint8_t d = *buf++;
- esc->fib_acc += esc->table[d & 0x0f];
- *out_data++ = esc->fib_acc;
- esc->fib_acc += esc->table[d >> 4];
- *out_data++ = esc->fib_acc;
- }
+ delta_decode(out_data, buf, buf_size, &esc->fib_acc, esc->table);
return consumed;
}
--
1.7.1
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