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/* Copyright (C) 2005 Ole André Vadla Ravnås <oleavr@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <string.h>
#include "mimic-private.h"
static gboolean decode(MimCtx *ctx, gboolean is_pframe);
/**
* Decode a MIMIC-encoded frame into RGB data.
*
* @param ctx the mimic context
* @param input_buffer buffer containing the MIMIC-encoded frame to decode
* @param output_buffer buffer that will receive the decoded frame in RGB 24-bpp packed pixel top-down format
* (use #mimic_get_property to determine the required buffer size, as well as frame width and height)
* @returns #TRUE on success
*/
gboolean mimic_decode_frame(MimCtx *ctx,
const guchar *input_buffer,
guchar *output_buffer)
{
gboolean result, is_pframe;
guchar *input_y, *input_cr, *input_cb;
gint width, height;
/*
* Some sanity checks.
*/
if (ctx == NULL || input_buffer == NULL || output_buffer == NULL)
{
return FALSE;
}
if (!ctx->decoder_initialized)
{
return FALSE;
}
/*
* Get frame dimensions.
*/
width = GUINT16_FROM_LE(*((guint16 *) (input_buffer + 4)));
height = GUINT16_FROM_LE(*((guint16 *) (input_buffer + 6)));
/*
* Resolution changing is not supported.
*/
if (width != ctx->frame_width ||
height != ctx->frame_height)
{
return FALSE;
}
/*
* Increment frame counter.
*/
ctx->frame_num++;
/*
* Initialize state.
*/
ctx->quality = GUINT16_FROM_LE(*((guint16 *) (input_buffer + 2)));
is_pframe = GUINT32_FROM_LE(*((guint32 *) (input_buffer + 12)));
ctx->num_coeffs = input_buffer[16];
ctx->data_buffer = (gchar *) (input_buffer + 20);
ctx->data_index = 0;
ctx->cur_chunk_len = 16;
ctx->read_odd = FALSE;
/*
* Decode frame.
*/
if (!(is_pframe && ctx->prev_frame_buf == NULL))
result = decode(ctx, is_pframe);
else
{
result = FALSE;
}
/*
* Perform YUV 420 to RGB conversion.
*/
input_y = ctx->cur_frame_buf;
input_cr = ctx->cur_frame_buf + ctx->y_size;
input_cb = ctx->cur_frame_buf + ctx->y_size + ctx->crcb_size;
_yuv_to_rgb(input_y,
input_cb,
input_cr,
output_buffer,
ctx->frame_width,
ctx->frame_height);
return result;
}
/*
* decode_main
*
* Main decoding loop.
*/
static gboolean decode(MimCtx *ctx, gboolean is_pframe)
{
gint y, x, i, j, chrom_ch, *bptr, base_offset, offset;
gint dct_block[64];
guchar *src, *dst, *p;
guint32 bit;
/*
* Clear Cr and Cb planes.
*/
p = ctx->cur_frame_buf + ctx->y_size;
memset(p, 128, 2 * ctx->crcb_size);
/*
* Decode Y plane.
*/
for (y = 0; y < ctx->num_vblocks_y; y++) {
base_offset = ctx->y_stride * 8 * y;
src = ctx->prev_frame_buf + base_offset;
dst = ctx->cur_frame_buf + base_offset;
for (x = 0; x < ctx->num_hblocks_y; x++) {
/* Check for a change condition in the current block. */
if (is_pframe)
bit = _read_bits(ctx, 1);
else
bit = 0;
if (bit == 0) {
/* Yes: Is the new content the same as it was in one of
* the 15 last frames preceding the previous? */
if (is_pframe)
bit = _read_bits(ctx, 1);
if (bit == 0) {
/* No: decode it. */
if (_vlc_decode_block(ctx, dct_block, ctx->num_coeffs) == FALSE) {
return FALSE;
}
_idct_dequant_block(ctx, dct_block, 0);
bptr = dct_block;
for (i = 0; i < 8; i++) {
offset = ctx->y_stride * i;
for (j = 0; j < 8; j++) {
guint v;
if (bptr[j] <= 255)
v = (bptr[j] >= 0) ? bptr[j] : 0;
else
v = 255;
*(dst + offset + j) = v;
}
bptr += 8;
}
} else {
guint32 backref;
/* Yes: read the backreference (4 bits) and copy. */
backref = _read_bits(ctx, 4);
p = ctx->buf_ptrs[(ctx->ptr_index + backref) % 16];
p += base_offset + (x * 8);
for (i = 0; i < 8; i++) {
offset = ctx->y_stride * i;
memcpy(dst + offset, p + offset, 8);
}
}
} else {
/* No change no worries: just copy from the previous frame. */
for (i = 0; i < 8; i++) {
offset = ctx->y_stride * i;
memcpy(dst + offset, src + offset, 8);
}
}
src += 8;
dst += 8;
}
}
/*
* Decode Cr and Cb planes.
*/
for (chrom_ch = 0; chrom_ch < 2; chrom_ch++) {
base_offset = ctx->y_size + (ctx->crcb_size * chrom_ch);
for (y = 0; y < ctx->num_vblocks_cbcr; y++) {
guint num_rows = 8;
/* The last row of blocks in chrominance for 160x120 resolution
* is half the normal height and must be accounted for. */
if (y + 1 == ctx->num_vblocks_cbcr && ctx->frame_height % 16 != 0)
num_rows = 4;
offset = base_offset + (ctx->crcb_stride * 8 * y);
src = ctx->prev_frame_buf + offset;
dst = ctx->cur_frame_buf + offset;
for (x = 0; x < ctx->num_hblocks_cbcr; x++) {
/* Check for a change condition in the current block. */
if (is_pframe)
bit = _read_bits(ctx, 1);
else
bit = 1;
if (bit == 1) {
/* Yes: decode it. */
if (_vlc_decode_block(ctx, dct_block, ctx->num_coeffs) == FALSE) {
/* Corrupted frame: clear Cr and Cb planes and return. */
p = ctx->cur_frame_buf + ctx->y_size;
memset(p, 128, ctx->crcb_size * 2);
return FALSE;
}
_idct_dequant_block(ctx, dct_block, 1);
for (i = 0; i < num_rows; i++) {
p = dst + (ctx->crcb_stride * i);
for (j = 0; j < 8; j++)
p[j] = dct_block[(i * 8) + j];
}
} else {
/* No change no worries: just copy from the previous frame. */
for (i = 0; i < num_rows; i++) {
offset = ctx->crcb_stride * i;
memcpy(dst + offset, src + offset, 8);
}
}
src += 8;
dst += 8;
}
}
}
/*
* Make a copy of the current frame and store in
* the circular pointer list of 16 entries.
*/
ctx->prev_frame_buf = ctx->buf_ptrs[ctx->ptr_index];
memcpy(ctx->prev_frame_buf, ctx->cur_frame_buf,
ctx->y_size + (ctx->crcb_size * 2));
if (--ctx->ptr_index < 0)
ctx->ptr_index = 15;
/*
* Perform deblocking on all planes.
*/
_deblock(ctx->cur_frame_buf,
ctx->y_stride, ctx->y_row_count);
_deblock(ctx->cur_frame_buf + ctx->y_size,
ctx->crcb_stride, ctx->crcb_row_count);
_deblock(ctx->cur_frame_buf + ctx->y_size + ctx->crcb_size,
ctx->crcb_stride, ctx->crcb_row_count);
return TRUE;
}
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