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mpv/roqav.c

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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 <stdio.h>
#include <stdlib.h>
#include "config.h"
#include "bswap.h"
#include "mp_msg.h"
#include "mp_image.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;
// RoQ chunk types
#define RoQ_INFO 0x1001
#define RoQ_QUAD_CODEBOOK 0x1002
#define RoQ_QUAD_VQ 0x1011
#define RoQ_SOUND_MONO 0x1020
#define RoQ_SOUND_STEREO 0x1021
#define MAX_ROQ_CODEBOOK_SIZE 256
// codebook entry for 2x2 vector
typedef struct
{
// upper and lower luminance value pairs of 2x2 vector: [y0 y1], [y2 y3]
unsigned short v2_y_u;
unsigned short v2_y_l;
// chrominance components
unsigned char u, v;
// maintain separate bytes for the luminance values as well
unsigned char y0, y1, y2, y3;
} roq_v2_codebook;
// codebook entry for 4x4 vector
typedef struct
{
// these variables are for rendering a 4x4 block built from 4 2x2
// vectors [va vb vc vd]; e.g.:
// v4_y_row1 = [va.y0 va.y1 vb.y0 vb.y1]
// v4_y_row4 = [vc.y2 vc.y3 vd.y2 vd.y3]
unsigned long v4_y_row1;
unsigned long v4_y_row2;
unsigned long v4_y_row3;
unsigned long v4_y_row4;
// ex: v4_u_row1 = [va.u vb.u]
// v4_u_row2 = [vc.u vd.u]
unsigned short v4_u_row1;
unsigned short v4_u_row2;
unsigned short v4_v_row1;
unsigned short v4_v_row2;
// these variables are for rendering a 4x4 block doublesized to an
// 8x8 block
// ex: v4d_y_rows_12_l contains the 4 luminance values used to paint
// the left half (4 pixels) of rows 1 and 2 of the 8x8 block, which
// will be comprised from the original 2x2 vectors as
// [va.y0 va.y0 va.y1 va.y1]
unsigned long v4d_y_rows_12_l;
unsigned long v4d_y_rows_12_r;
unsigned long v4d_y_rows_34_l;
unsigned long v4d_y_rows_34_r;
unsigned long v4d_y_rows_56_l;
unsigned long v4d_y_rows_56_r;
unsigned long v4d_y_rows_78_l;
unsigned long v4d_y_rows_78_r;
// doublesized chrominance values
// ex: v4d_u_rows_12 = [va.u va.u vb.u vb.u]
unsigned long v4d_u_rows_12;
unsigned long v4d_u_rows_34;
unsigned long v4d_v_rows_12;
unsigned long v4d_v_rows_34;
} roq_v4_codebook;
typedef struct
{
roq_v2_codebook v2[MAX_ROQ_CODEBOOK_SIZE];
roq_v4_codebook v4[MAX_ROQ_CODEBOOK_SIZE];
mp_image_t *prev_frame;
} roqvideo_info;
// This function fills in the missing information for a v2 vector after
// loading the Y, U and V values.
inline void prep_v2(roq_v2_codebook *v2)
{
v2->v2_y_u = be2me_16((v2->y0 << 8) | v2->y1);
v2->v2_y_l = be2me_16((v2->y2 << 8) | v2->y3);
}
// This function fills in the missing information for a v4 vector based
// on 4 v2 indices.
void prep_v4(roq_v4_codebook *v4,
roq_v2_codebook *v2_a, roq_v2_codebook *v2_b,
roq_v2_codebook *v2_c, roq_v2_codebook *v2_d)
{
// fill in the v4 variables
v4->v4_y_row1 = be2me_32((v2_a->v2_y_u << 16) | v2_b->v2_y_u);
v4->v4_y_row2 = be2me_32((v2_a->v2_y_l << 16) | v2_b->v2_y_l);
v4->v4_y_row3 = be2me_32((v2_c->v2_y_u << 16) | v2_d->v2_y_u);
v4->v4_y_row4 = be2me_32((v2_c->v2_y_l << 16) | v2_d->v2_y_l);
v4->v4_u_row1 = be2me_16((v2_a->u << 8) | v2_b->u);
v4->v4_u_row2 = be2me_16((v2_c->u << 8) | v2_d->u);
v4->v4_v_row1 = be2me_16((v2_a->v << 8) | v2_b->v);
v4->v4_v_row2 = be2me_16((v2_c->v << 8) | v2_d->v);
// fill in the doublesized v4 variables
v4->v4d_y_rows_12_l = be2me_32((v2_a->y0 << 24) | (v2_a->y0 << 16) |
(v2_a->y1 << 8) | v2_a->y1);
v4->v4d_y_rows_12_r = be2me_32((v2_b->y0 << 24) | (v2_b->y0 << 16) |
(v2_b->y1 << 8) | v2_b->y1);
v4->v4d_y_rows_34_l = be2me_32((v2_a->y2 << 24) | (v2_a->y2 << 16) |
(v2_a->y3 << 8) | v2_a->y3);
v4->v4d_y_rows_34_r = be2me_32((v2_b->y2 << 24) | (v2_b->y2 << 16) |
(v2_b->y3 << 8) | v2_b->y3);
v4->v4d_y_rows_56_l = be2me_32((v2_c->y0 << 24) | (v2_c->y0 << 16) |
(v2_c->y1 << 8) | v2_c->y1);
v4->v4d_y_rows_56_r = be2me_32((v2_d->y0 << 24) | (v2_d->y0 << 16) |
(v2_d->y1 << 8) | v2_d->y1);
v4->v4d_y_rows_78_l = be2me_32((v2_c->y2 << 24) | (v2_c->y2 << 16) |
(v2_d->y3 << 8) | v2_d->y3);
v4->v4d_y_rows_78_r = be2me_32((v2_c->y2 << 24) | (v2_c->y2 << 16) |
(v2_d->y3 << 8) | v2_d->y3);
v4->v4d_u_rows_12 = be2me_32((v2_a->u << 24) | (v2_a->u << 16) |
(v2_b->u << 8) | v2_b->u);
v4->v4d_u_rows_34 = be2me_32((v2_c->u << 24) | (v2_c->u << 16) |
(v2_d->u << 8) | v2_d->u);
v4->v4d_v_rows_12 = be2me_32((v2_a->v << 24) | (v2_a->v << 16) |
(v2_b->v << 8) | v2_b->v);
v4->v4d_v_rows_34 = be2me_32((v2_c->v << 24) | (v2_c->v << 16) |
(v2_d->v << 8) | v2_d->v);
}
// This function copies the 4x4 block from the prev_*_planes to the
// current *_planes.
inline void copy_4x4_block(
unsigned char *y_plane,
unsigned char *u_plane,
unsigned char *v_plane,
unsigned char *prev_y_plane,
unsigned char *prev_u_plane,
unsigned char *prev_v_plane,
unsigned int y_stride,
unsigned int u_stride,
unsigned int v_stride)
{
int i;
// copy over the luminance components (4 rows, 2 uints each)
for (i = 0; i < 4; i++)
{
*(unsigned int *)y_plane = *(unsigned int *)prev_y_plane;
y_plane += y_stride;
prev_y_plane += y_stride;
}
// copy the chrominance values
for (i = 0; i < 2; i++)
{
*(unsigned short*)u_plane = *(unsigned short*)prev_u_plane;
u_plane += u_stride;
*(unsigned short*)v_plane = *(unsigned short*)prev_v_plane;
v_plane += v_stride;
}
}
// This function copies the 8x8 block from the prev_*_planes to the
// current *_planes.
inline void copy_8x8_block(
unsigned char *y_plane,
unsigned char *u_plane,
unsigned char *v_plane,
unsigned char *prev_y_plane,
unsigned char *prev_u_plane,
unsigned char *prev_v_plane,
unsigned int y_stride,
unsigned int u_stride,
unsigned int v_stride)
{
int i;
// copy over the luminance components (8 rows, 2 uints each)
for (i = 0; i < 8; i++)
{
((unsigned int *)y_plane)[0] = ((unsigned int *)prev_y_plane)[0];
((unsigned int *)y_plane)[1] = ((unsigned int *)prev_y_plane)[1];
y_plane += y_stride;
prev_y_plane += y_stride;
}
// copy the chrominance values
for (i = 0; i < 4; i++)
{
*(unsigned int*)u_plane = *(unsigned int*)prev_u_plane;
u_plane += u_stride;
*(unsigned int*)v_plane = *(unsigned int*)prev_v_plane;
v_plane += v_stride;
}
}
// This function creates storage space for the vector codebooks.
void *roq_decode_video_init(void)
{
roqvideo_info *info =
(roqvideo_info *)malloc(sizeof(roqvideo_info));
info->prev_frame = NULL;
return info;
}
#define EMPTY_ROQ_CODEWORD 0xFFFF0000
#define FETCH_NEXT_CODE() \
if (current_roq_codeword == EMPTY_ROQ_CODEWORD) \
{ \
if (stream_ptr + 2 > encoded_size) \
{ \
mp_msg(MSGT_DECVIDEO, MSGL_WARN, \
"RoQ video: stream pointer just went out of bounds (1)\n"); \
return; \
} \
current_roq_codeword = (0x0000FFFF) | \
(encoded[stream_ptr + 0] << 16) | \
(encoded[stream_ptr + 1] << 24); \
stream_ptr += 2; \
} \
roq_code = ((current_roq_codeword >> 30) & 0x03); \
current_roq_codeword <<= 2;
#define FETCH_NEXT_ARGUMENT() \
if (stream_ptr + 1 > encoded_size) \
{ \
mp_msg(MSGT_DECVIDEO, MSGL_WARN, \
"RoQ video: stream pointer just went out of bounds (2)\n"); \
return; \
} \
argument = encoded[stream_ptr++];
#define CHECK_PREV_FRAME() \
if (!info->prev_frame) \
{ \
mp_msg(MSGT_DECVIDEO, MSGL_WARN, \
"RoQ video: can't handle motion vector when there's no previous frame\n"); \
return; \
}
void roq_decode_video(void *context, unsigned char *encoded,
int encoded_size, mp_image_t *mpi)
{
roqvideo_info *info = (roqvideo_info *)context;
int stream_ptr = 0;
int i, j, k;
int chunk_length;
int v2_count;
int v4_count;
int v2_ia, v2_ib, v2_ic, v2_id;
int roq_code;
unsigned int current_roq_codeword = EMPTY_ROQ_CODEWORD;
unsigned char argument = 0;
int mean_motion_x;
int mean_motion_y;
int mx, my; // for calculating the motion vector
int mblock_x = 0;
int mblock_y = 0;
int quad8_x, quad8_y; // for pointing to 8x8 blocks in a macroblock
int quad4_x, quad4_y; // for pointing to 4x4 blocks in an 8x8 block
int quad2_x, quad2_y; // for pointing to 2x2 blocks in a 4x4 block
unsigned char *y_plane;
unsigned char *u_plane;
unsigned char *v_plane;
unsigned char *prev_y_plane;
unsigned char *prev_u_plane;
unsigned char *prev_v_plane;
unsigned int y_stride = mpi->stride[0];
unsigned int u_stride = mpi->stride[1];
unsigned int v_stride = mpi->stride[2];
roq_v4_codebook v4;
roq_v2_codebook v2;
int debugger = 0;
// make sure the encoded chunk is of minimal acceptable length
if (encoded_size < 8)
{
mp_msg(MSGT_DECVIDEO, MSGL_WARN,
"RoQ video: chunk isn't even 8 bytes long (minimum acceptable length)\n");
return;
}
// make sure the resolution checks out
if ((mpi->width % 16 != 0) || (mpi->height % 16 != 0))
{
mp_msg(MSGT_DECVIDEO, MSGL_WARN,
"RoQ video resolution: %d x %d; expected dimensions divisible by 16\n");
return;
}
if (LE_16(&encoded[stream_ptr]) == RoQ_QUAD_CODEBOOK)
{
if (debugger)
printf ("parsing codebook\n");
stream_ptr += 2;
chunk_length = LE_32(&encoded[stream_ptr]);
stream_ptr += 4;
v4_count = encoded[stream_ptr++];
v2_count = encoded[stream_ptr++];
if (v2_count == 0)
v2_count = 256;
if ((v4_count == 0) && (v2_count * 6 < chunk_length))
v4_count = 256;
// make sure the lengths agree with each other
if (((v2_count * 6) + (v4_count * 4)) != chunk_length)
{
mp_msg(MSGT_DECVIDEO, MSGL_WARN,
"RoQ video: encountered quad codebook chunk with weird lengths (1)\n");
return;
}
if ((v2_count * 6) > (encoded_size - stream_ptr))
{
mp_msg(MSGT_DECVIDEO, MSGL_WARN,
"RoQ video: encountered quad codebook chunk with weird lengths (2)\n");
return;
}
// load the 2x2 vectors
for (i = 0; i < v2_count; i++)
{
info->v2[i].y0 = encoded[stream_ptr++];
info->v2[i].y1 = encoded[stream_ptr++];
info->v2[i].y2 = encoded[stream_ptr++];
info->v2[i].y3 = encoded[stream_ptr++];
info->v2[i].u = encoded[stream_ptr++];
info->v2[i].v = encoded[stream_ptr++];
prep_v2(&info->v2[i]);
}
if ((v4_count * 4) > (encoded_size - stream_ptr))
{
mp_msg(MSGT_DECVIDEO, MSGL_WARN,
"RoQ video: encountered quad codebook chunk with weird lengths (3)\n");
return;
}
// load the 4x4 vectors
for (i = 0; i < v4_count; i++)
{
v2_ia = encoded[stream_ptr++];
v2_ib = encoded[stream_ptr++];
v2_ic = encoded[stream_ptr++];
v2_id = encoded[stream_ptr++];
prep_v4(&info->v4[i], &info->v2[v2_ia], &info->v2[v2_ib],
&info->v2[v2_ic], &info->v2[v2_id]);
}
}
if (LE_16(&encoded[stream_ptr]) == RoQ_QUAD_VQ)
{
if (debugger)
printf ("parsing quad vq\n");
stream_ptr += 2;
chunk_length = LE_32(&encoded[stream_ptr]);
stream_ptr += 4;
mean_motion_y = encoded[stream_ptr++];
mean_motion_x = encoded[stream_ptr++];
if (debugger){
for (i = 0; i < 16; i++)
printf (" %02X", encoded[stream_ptr + i]);
printf("\n");}
// iterate through the 16x16 macroblocks
for (mblock_y = 0; mblock_y < mpi->height; mblock_y += 16)
{
for (mblock_x = 0; mblock_x < mpi->width; mblock_x += 16)
{
// iterate through the 4 quadrants of the macroblock
for (i = 0; i < 4; i++)
{
quad8_x = mblock_x;
quad8_y = mblock_y;
if (i & 0x01) quad8_x += 8;
if (i & 0x02) quad8_y += 8;
// set up the planes
y_plane = mpi->planes[0] + quad8_y * y_stride + quad8_x;
u_plane = mpi->planes[1] + (quad8_y / 2) * u_stride + (quad8_x / 2);
v_plane = mpi->planes[2] + (quad8_y / 2) * v_stride + (quad8_x / 2);
// decide how to handle this 8x8 quad
FETCH_NEXT_CODE();
if (debugger)
printf (" (%d, %d), %d\n", quad8_x, quad8_y, roq_code);
switch(roq_code)
{
// 8x8 block is painted with the same block as the last frame
case 0:
CHECK_PREV_FRAME();
// prepare the pointers to the planes in the previous frame
prev_y_plane = info->prev_frame->planes[0] +
quad8_y * y_stride + quad8_x;
prev_u_plane = info->prev_frame->planes[1] +
(quad8_y / 2) * u_stride + (quad8_x / 2);
prev_v_plane = info->prev_frame->planes[2] +
(quad8_y / 2) * v_stride + (quad8_x / 2);
// sanity check before rendering
copy_8x8_block(
y_plane,
u_plane,
v_plane,
prev_y_plane,
prev_u_plane,
prev_v_plane,
y_stride,
u_stride,
v_stride
);
break;
// 8x8 block is painted with an 8x8 block from the last frame
// (i.e., motion compensation)
case 1:
CHECK_PREV_FRAME();
// prepare the pointers to the planes in the previous frame
FETCH_NEXT_ARGUMENT(); // argument contains motion vectors
// figure out the motion vectors
mx = quad8_x + 8 - (argument >> 4) - mean_motion_x;
my = quad8_y + 8 - (argument & 0x0F) - mean_motion_y;
prev_y_plane = info->prev_frame->planes[0] +
my * y_stride + mx;
prev_u_plane = info->prev_frame->planes[1] +
(my / 2) * u_stride + (mx + 1) / 2;
prev_v_plane = info->prev_frame->planes[2] +
(my / 2) * v_stride + (mx + 1) / 2;
// sanity check before rendering
copy_8x8_block(
y_plane,
u_plane,
v_plane,
prev_y_plane,
prev_u_plane,
prev_v_plane,
y_stride,
u_stride,
v_stride
);
break;
// 8x8 block is painted with a doublesized 4x4 vector
case 2:
FETCH_NEXT_ARGUMENT();
v4 = info->v4[argument];
if (debugger)
printf (" vector: %d, %08X %08X %08X %08X %08X %08X\n", argument,
v4.v4d_y_rows_12_l, v4.v4d_y_rows_12_r,
v4.v4d_y_rows_34_l, v4.v4d_y_rows_34_r,
v4.v4d_u_rows_12, v4.v4d_u_rows_34);
// sanity check before rendering
// take care of the 8 luminance rows
((unsigned int*)y_plane)[0] = v4.v4d_y_rows_12_l;
((unsigned int*)y_plane)[1] = v4.v4d_y_rows_12_r;
y_plane += y_stride;
((unsigned int*)y_plane)[0] = v4.v4d_y_rows_12_l;
((unsigned int*)y_plane)[1] = v4.v4d_y_rows_12_r;
y_plane += y_stride;
((unsigned int*)y_plane)[0] = v4.v4d_y_rows_34_l;
((unsigned int*)y_plane)[1] = v4.v4d_y_rows_34_r;
y_plane += y_stride;
((unsigned int*)y_plane)[0] = v4.v4d_y_rows_34_l;
((unsigned int*)y_plane)[1] = v4.v4d_y_rows_34_r;
y_plane += y_stride;
((unsigned int*)y_plane)[0] = v4.v4d_y_rows_56_l;
((unsigned int*)y_plane)[1] = v4.v4d_y_rows_56_r;
y_plane += y_stride;
((unsigned int*)y_plane)[0] = v4.v4d_y_rows_56_l;
((unsigned int*)y_plane)[1] = v4.v4d_y_rows_56_r;
y_plane += y_stride;
((unsigned int*)y_plane)[0] = v4.v4d_y_rows_78_l;
((unsigned int*)y_plane)[1] = v4.v4d_y_rows_78_r;
y_plane += y_stride;
((unsigned int*)y_plane)[0] = v4.v4d_y_rows_78_l;
((unsigned int*)y_plane)[1] = v4.v4d_y_rows_78_r;
// then the 4 U & V chrominance rows
*(unsigned int*)u_plane = v4.v4d_u_rows_12;
u_plane += u_stride;
*(unsigned int*)u_plane = v4.v4d_u_rows_12;
u_plane += u_stride;
*(unsigned int*)u_plane = v4.v4d_u_rows_34;
u_plane += u_stride;
*(unsigned int*)u_plane = v4.v4d_u_rows_34;
*(unsigned int*)v_plane = v4.v4d_v_rows_12;
v_plane += v_stride;
*(unsigned int*)v_plane = v4.v4d_v_rows_12;
v_plane += v_stride;
*(unsigned int*)v_plane = v4.v4d_v_rows_34;
v_plane += v_stride;
*(unsigned int*)v_plane = v4.v4d_v_rows_34;
break;
// 8x8 block is broken down into 4 4x4 blocks and painted using
// 4 different codes.
case 3:
// iterate through 4 4x4 blocks
for (j = 0; j < 4; j++)
{
quad4_x = quad8_x;
quad4_y = quad8_y;
if (j & 0x01) quad4_x += 4;
if (j & 0x02) quad4_y += 4;
// set up the planes
y_plane = mpi->planes[0] + quad4_y * y_stride + quad4_x;
u_plane = mpi->planes[1] +
(quad4_y / 2) * u_stride + (quad4_x / 2);
v_plane = mpi->planes[2] +
(quad4_y / 2) * v_stride + (quad4_x / 2);
// decide how to handle this 4x4 quad
FETCH_NEXT_CODE();
if (debugger)
printf (" (%d, %d), %d\n", quad4_x, quad4_y, roq_code);
switch(roq_code)
{
// 4x4 block is the same as in the previous frame
case 0:
CHECK_PREV_FRAME();
// prepare the pointers to the planes in the previous frame
prev_y_plane = info->prev_frame->planes[0] +
quad4_y * y_stride + quad4_x;
prev_u_plane = info->prev_frame->planes[1] +
(quad4_y / 2) * u_stride + (quad4_x / 2);
prev_v_plane = info->prev_frame->planes[2] +
(quad4_y / 2) * v_stride + (quad4_x / 2);
// sanity check before rendering
copy_4x4_block(
y_plane,
u_plane,
v_plane,
prev_y_plane,
prev_u_plane,
prev_v_plane,
y_stride,
u_stride,
v_stride
);
break;
// 4x4 block is motion compensated from the previous frame
case 1:
CHECK_PREV_FRAME();
// prepare the pointers to the planes in the previous frame
FETCH_NEXT_ARGUMENT(); // argument contains motion vectors
// figure out the motion vectors
mx = quad4_x + 8 - (argument >> 4) - mean_motion_x;
my = quad4_y + 8 - (argument & 0x0F) - mean_motion_y;
prev_y_plane = info->prev_frame->planes[0] +
my * y_stride + mx;
prev_u_plane = info->prev_frame->planes[1] +
(my / 2) * u_stride + (mx + 1) / 2;
prev_v_plane = info->prev_frame->planes[2] +
(my / 2) * u_stride + (mx + 1) / 2;
// sanity check before rendering
copy_4x4_block(
y_plane,
u_plane,
v_plane,
prev_y_plane,
prev_u_plane,
prev_v_plane,
y_stride,
u_stride,
v_stride
);
break;
// 4x4 block is copied directly from v4 vector table
case 2:
FETCH_NEXT_ARGUMENT();
v4 = info->v4[argument];
// copy the 4 luminance rows
*(unsigned int*)y_plane = v4.v4_y_row1;
y_plane += y_stride;
*(unsigned int*)y_plane = v4.v4_y_row2;
y_plane += y_stride;
*(unsigned int*)y_plane = v4.v4_y_row3;
y_plane += y_stride;
*(unsigned int*)y_plane = v4.v4_y_row4;
// copy the U & V chrominance rows
*(unsigned short*)u_plane = v4.v4_u_row1;
u_plane += u_stride;
*(unsigned short*)u_plane = v4.v4_u_row2;
*(unsigned short*)v_plane = v4.v4_v_row1;
v_plane += v_stride;
*(unsigned short*)v_plane = v4.v4_v_row2;
break;
// 4x4 block is built from 4 2x2 vectors
case 3:
// iterate through 4 2x2 blocks
for (k = 0; k < 4; k++)
{
quad2_x = quad4_x;
quad2_y = quad4_y;
if (k & 0x01) quad2_x += 2;
if (k & 0x02) quad2_y += 2;
// set up the planes
y_plane = mpi->planes[0] + quad2_y * y_stride + quad2_x;
u_plane = mpi->planes[1] +
(quad2_y / 2) * u_stride + (quad2_x / 2);
v_plane = mpi->planes[2] +
(quad2_y / 2) * v_stride + (quad2_x / 2);
// fetch the next index into the v2 vector table
FETCH_NEXT_ARGUMENT();
if (debugger)
printf (" (%d, %d), %d\n", quad2_x, quad2_y, argument);
v2 = info->v2[argument];
// copy the luminance components
*(unsigned short*)y_plane = v2.v2_y_u;
y_plane += y_stride;
*(unsigned short*)y_plane = v2.v2_y_l;
// copy the U and V bytes
u_plane[0] = v2.u;
v_plane[0] = v2.v;
}
break;
}
}
break;
}
}
}
}
}
// one last sanity check on the way out
// (apparently, it's not unusual to have 2 bytes left over after decode)
if (stream_ptr < encoded_size - 2)
{
mp_msg(MSGT_DECVIDEO, MSGL_WARN,
"RoQ video: completed frame decode with bytes left over (%d < %d)\n",
stream_ptr, encoded_size);
}
// save the current frame as the previous frame for the next iteration
info->prev_frame = mpi;
}
// 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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