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8svx: split delta decoding into a separate function.

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Based on a patch by Stefano Sabatini.
git.videolan.org/ffmpeg.git
commit e280a4da2a
This commit is contained in:
Justin Ruggles 2011-09-06 15:13:59 -04:00
parent 1c2e07b811
commit ac68607bfe
1 changed files with 23 additions and 7 deletions
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30
libavcodec/8svx.c
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@ -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;
}