mirror of
https://github.com/mpv-player/mpv
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80168a072d
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@4487 b3059339-0415-0410-9bf9-f77b7e298cf2
95 lines
1.9 KiB
C
95 lines
1.9 KiB
C
/*
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RoQ A/V decoder for the MPlayer program
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by Mike Melanson
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based on Dr. Tim Ferguson's RoQ document and accompanying source
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code found at:
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http://www.csse.monash.edu.au/~timf/videocodec.html
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*/
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#include "config.h"
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#include "bswap.h"
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#include <stdio.h>
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#include <stdlib.h>
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#define LE_16(x) (le2me_16(*(unsigned short *)(x)))
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#define LE_32(x) (le2me_32(*(unsigned int *)(x)))
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#define CLAMP_S16(x) if (x < -32768) x = -32768; \
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else if (x > 32767) x = 32767;
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#define SE_16BIT(x) if (x & 0x8000) x -= 0x10000;
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// sign extend a 4-bit value
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void *roq_decode_video_init(void)
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{
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}
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void roq_decode_video(
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unsigned char *encoded,
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int encoded_size,
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unsigned char *decoded,
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int width,
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int height,
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void *context)
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{
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}
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// Initialize the RoQ audio decoder, which is to say, initialize the table
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// of squares.
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void *roq_decode_audio_init(void)
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{
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short *square_array;
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short square;
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int i;
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square_array = (short *)malloc(256 * sizeof(short));
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if (!square_array)
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return NULL;
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for (i = 0; i < 128; i++)
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{
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square = i * i;
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square_array[i] = square;
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square_array[i + 128] = -square;
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}
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return square_array;
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}
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int roq_decode_audio(
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unsigned short *output,
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unsigned char *input,
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int encoded_size,
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int channels,
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void *context)
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{
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short *square_array = (short *)context;
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int i;
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int predictor[2];
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int channel_number = 0;
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// prepare the initial predictors
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if (channels == 1)
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predictor[0] = LE_16(&input[0]);
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else
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{
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predictor[0] = input[1] << 8;
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predictor[1] = input[0] << 8;
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}
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SE_16BIT(predictor[0]);
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SE_16BIT(predictor[1]);
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// decode the samples
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for (i = 2; i < encoded_size; i++)
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{
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predictor[channel_number] += square_array[input[i]];
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CLAMP_S16(predictor[channel_number]);
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output[i - 2] = predictor[channel_number];
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// toggle channel
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channel_number ^= channels - 1;
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}
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// return the number of samples decoded
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return (encoded_size - 2);
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}
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