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authorJustin Ruggles2011-09-06 15:13:59 -0400
committerJustin Ruggles2011-09-22 14:11:34 -0400
commitac68607bfe62000520db2e1c2416c11c51b3b295 (patch)
tree9c19401b1d0d93cfc6503aff225f8cb7803f3ba3 /libavcodec/8svx.c
parent1c2e07b8111b24f62b8d1bda62907848e34dfbcb (diff)
8svx: split delta decoding into a separate function.
Based on a patch by Stefano Sabatini. git.videolan.org/ffmpeg.git commit e280a4da2ae6fd44f0079358ecc5aa08e388a5ed
Diffstat (limited to 'libavcodec/8svx.c')
-rw-r--r--libavcodec/8svx.c30
1 files changed, 23 insertions, 7 deletions
diff --git a/libavcodec/8svx.c b/libavcodec/8svx.c
index 4b60377128..dccaadddb0 100644
--- a/libavcodec/8svx.c
+++ b/libavcodec/8svx.c
@@ -41,6 +41,28 @@ 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.
+ *
+ * @param[in,out] state starting value. it is saved for use in the next call.
+ */
+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)
@@ -63,13 +85,7 @@ static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int *data_si
*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;
}