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/*
RoQ A/V decoder for the MPlayer program
by Mike Melanson
based on Dr. Tim Ferguson's RoQ document and accompanying source
code found at:
http://www.csse.monash.edu.au/~timf/videocodec.html
*/
#include "config.h"
#include "bswap.h"
#include <stdio.h>
#include <stdlib.h>
#define LE_16(x) (le2me_16(*(unsigned short *)(x)))
#define LE_32(x) (le2me_32(*(unsigned int *)(x)))
#define CLAMP_S16(x) if (x < -32768) x = -32768; \
else if (x > 32767) x = 32767;
#define SE_16BIT(x) if (x & 0x8000) x -= 0x10000;
// sign extend a 4-bit value
void *roq_decode_video_init(void)
{
}
void roq_decode_video(
unsigned char *encoded,
int encoded_size,
unsigned char *decoded,
int width,
int height,
void *context)
{
}
// Initialize the RoQ audio decoder, which is to say, initialize the table
// of squares.
void *roq_decode_audio_init(void)
{
short *square_array;
short square;
int i;
square_array = (short *)malloc(256 * sizeof(short));
if (!square_array)
return NULL;
for (i = 0; i < 128; i++)
{
square = i * i;
square_array[i] = square;
square_array[i + 128] = -square;
}
return square_array;
}
int roq_decode_audio(
unsigned short *output,
unsigned char *input,
int encoded_size,
int channels,
void *context)
{
short *square_array = (short *)context;
int i;
int predictor[2];
int channel_number = 0;
// prepare the initial predictors
if (channels == 1)
predictor[0] = LE_16(&input[0]);
else
{
predictor[0] = input[1] << 8;
predictor[1] = input[0] << 8;
}
SE_16BIT(predictor[0]);
SE_16BIT(predictor[1]);
// decode the samples
for (i = 2; i < encoded_size; i++)
{
predictor[channel_number] += square_array[input[i]];
CLAMP_S16(predictor[channel_number]);
output[i - 2] = predictor[channel_number];
// toggle channel
channel_number ^= channels - 1;
}
// return the number of samples decoded
return (encoded_size - 2);
}
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