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* Quicktime Graphics (SMC) Video Decoder
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* Copyright (C) 2003 the ffmpeg project
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* QT SMC Video Decoder by Mike Melanson (melanson@pcisys.net)
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* For more information about the SMC format, visit:
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* http://www.pcisys.net/~melanson/codecs/
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* The SMC decoder outputs PAL8 colorspace data.
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#define COLORS_PER_TABLE 256
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typedef struct SmcContext {
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AVCodecContext *avctx;
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/* SMC color tables */
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unsigned char color_pairs[COLORS_PER_TABLE * CPAIR];
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unsigned char color_quads[COLORS_PER_TABLE * CQUAD];
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unsigned char color_octets[COLORS_PER_TABLE * COCTET];
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#define GET_BLOCK_COUNT() \
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(opcode & 0x10) ? (1 + s->buf[stream_ptr++]) : 1 + (opcode & 0x0F);
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#define ADVANCE_BLOCK() \
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if (pixel_ptr >= width) \
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row_ptr += stride * 4; \
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if (total_blocks < 0) \
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av_log(s->avctx, AV_LOG_INFO, "warning: block counter just went negative (this should not happen)\n"); \
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static void smc_decode_stream(SmcContext *s)
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int width = s->avctx->width;
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int height = s->avctx->height;
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int stride = s->frame.linesize[0];
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unsigned int color_flags;
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unsigned int color_flags_a;
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unsigned int color_flags_b;
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unsigned int flag_mask;
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unsigned char *pixels = s->frame.data[0];
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int image_size = height * s->frame.linesize[0];
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int pixel_x, pixel_y;
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int row_inc = stride - 4;
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int prev_block_ptr1, prev_block_ptr2;
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int color_table_index; /* indexes to color pair, quad, or octet tables */
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int color_pair_index = 0;
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int color_quad_index = 0;
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int color_octet_index = 0;
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/* make the palette available */
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memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);
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if (s->avctx->palctrl->palette_changed) {
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s->frame.palette_has_changed = 1;
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s->avctx->palctrl->palette_changed = 0;
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chunk_size = BE_32(&s->buf[stream_ptr]) & 0x00FFFFFF;
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if (chunk_size != s->size)
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av_log(s->avctx, AV_LOG_INFO, "warning: MOV chunk size != encoded chunk size (%d != %d); using MOV chunk size\n",
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chunk_size, s->size);
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chunk_size = s->size;
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total_blocks = ((s->avctx->width + 3) / 4) * ((s->avctx->height + 3) / 4);
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/* traverse through the blocks */
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while (total_blocks) {
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/* make sure stream ptr hasn't gone out of bounds */
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if (stream_ptr > chunk_size) {
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av_log(s->avctx, AV_LOG_INFO, "SMC decoder just went out of bounds (stream ptr = %d, chunk size = %d)\n",
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stream_ptr, chunk_size);
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/* make sure the row pointer hasn't gone wild */
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if (row_ptr >= image_size) {
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av_log(s->avctx, AV_LOG_INFO, "SMC decoder just went out of bounds (row ptr = %d, height = %d)\n",
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row_ptr, image_size);
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opcode = s->buf[stream_ptr++];
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switch (opcode & 0xF0) {
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n_blocks = GET_BLOCK_COUNT();
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/* repeat last block n times */
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n_blocks = GET_BLOCK_COUNT();
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if ((row_ptr == 0) && (pixel_ptr == 0)) {
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av_log(s->avctx, AV_LOG_INFO, "encountered repeat block opcode (%02X) but no blocks rendered yet\n",
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/* figure out where the previous block started */
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(row_ptr - s->avctx->width * 4) + s->avctx->width - 4;
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prev_block_ptr1 = row_ptr + pixel_ptr - 4;
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block_ptr = row_ptr + pixel_ptr;
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prev_block_ptr = prev_block_ptr1;
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for (pixel_y = 0; pixel_y < 4; pixel_y++) {
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for (pixel_x = 0; pixel_x < 4; pixel_x++) {
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pixels[block_ptr++] = pixels[prev_block_ptr++];
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block_ptr += row_inc;
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prev_block_ptr += row_inc;
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/* repeat previous pair of blocks n times */
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n_blocks = GET_BLOCK_COUNT();
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if ((row_ptr == 0) && (pixel_ptr < 2 * 4)) {
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av_log(s->avctx, AV_LOG_INFO, "encountered repeat block opcode (%02X) but not enough blocks rendered yet\n",
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/* figure out where the previous 2 blocks started */
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prev_block_ptr1 = (row_ptr - s->avctx->width * 4) +
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s->avctx->width - 4 * 2;
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else if (pixel_ptr == 4)
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prev_block_ptr1 = (row_ptr - s->avctx->width * 4) + row_inc;
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prev_block_ptr1 = row_ptr + pixel_ptr - 4 * 2;
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prev_block_ptr2 = (row_ptr - s->avctx->width * 4) + row_inc;
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prev_block_ptr2 = row_ptr + pixel_ptr - 4;
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block_ptr = row_ptr + pixel_ptr;
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prev_block_ptr = prev_block_ptr2;
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prev_block_ptr = prev_block_ptr1;
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prev_block_flag = !prev_block_flag;
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for (pixel_y = 0; pixel_y < 4; pixel_y++) {
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for (pixel_x = 0; pixel_x < 4; pixel_x++) {
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pixels[block_ptr++] = pixels[prev_block_ptr++];
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block_ptr += row_inc;
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prev_block_ptr += row_inc;
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/* 1-color block encoding */
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n_blocks = GET_BLOCK_COUNT();
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pixel = s->buf[stream_ptr++];
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block_ptr = row_ptr + pixel_ptr;
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for (pixel_y = 0; pixel_y < 4; pixel_y++) {
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for (pixel_x = 0; pixel_x < 4; pixel_x++) {
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pixels[block_ptr++] = pixel;
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block_ptr += row_inc;
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/* 2-color block encoding */
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n_blocks = (opcode & 0x0F) + 1;
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/* figure out which color pair to use to paint the 2-color block */
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if ((opcode & 0xF0) == 0x80) {
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/* fetch the next 2 colors from bytestream and store in next
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* available entry in the color pair table */
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for (i = 0; i < CPAIR; i++) {
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pixel = s->buf[stream_ptr++];
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color_table_index = CPAIR * color_pair_index + i;
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s->color_pairs[color_table_index] = pixel;
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/* this is the base index to use for this block */
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color_table_index = CPAIR * color_pair_index;
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if (color_pair_index == COLORS_PER_TABLE)
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color_pair_index = 0;
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color_table_index = CPAIR * s->buf[stream_ptr++];
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color_flags = BE_16(&s->buf[stream_ptr]);
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block_ptr = row_ptr + pixel_ptr;
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for (pixel_y = 0; pixel_y < 4; pixel_y++) {
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for (pixel_x = 0; pixel_x < 4; pixel_x++) {
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if (color_flags & flag_mask)
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pixel = color_table_index + 1;
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pixel = color_table_index;
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pixels[block_ptr++] = s->color_pairs[pixel];
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block_ptr += row_inc;
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/* 4-color block encoding */
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n_blocks = (opcode & 0x0F) + 1;
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/* figure out which color quad to use to paint the 4-color block */
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if ((opcode & 0xF0) == 0xA0) {
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/* fetch the next 4 colors from bytestream and store in next
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* available entry in the color quad table */
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for (i = 0; i < CQUAD; i++) {
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pixel = s->buf[stream_ptr++];
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color_table_index = CQUAD * color_quad_index + i;
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s->color_quads[color_table_index] = pixel;
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/* this is the base index to use for this block */
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color_table_index = CQUAD * color_quad_index;
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if (color_quad_index == COLORS_PER_TABLE)
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color_quad_index = 0;
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color_table_index = CQUAD * s->buf[stream_ptr++];
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color_flags = BE_32(&s->buf[stream_ptr]);
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/* flag mask actually acts as a bit shift count here */
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block_ptr = row_ptr + pixel_ptr;
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for (pixel_y = 0; pixel_y < 4; pixel_y++) {
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for (pixel_x = 0; pixel_x < 4; pixel_x++) {
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pixel = color_table_index +
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((color_flags >> flag_mask) & 0x03);
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pixels[block_ptr++] = s->color_quads[pixel];
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block_ptr += row_inc;
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/* 8-color block encoding */
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n_blocks = (opcode & 0x0F) + 1;
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/* figure out which color octet to use to paint the 8-color block */
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if ((opcode & 0xF0) == 0xC0) {
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/* fetch the next 8 colors from bytestream and store in next
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* available entry in the color octet table */
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for (i = 0; i < COCTET; i++) {
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pixel = s->buf[stream_ptr++];
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color_table_index = COCTET * color_octet_index + i;
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s->color_octets[color_table_index] = pixel;
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/* this is the base index to use for this block */
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color_table_index = COCTET * color_octet_index;
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if (color_octet_index == COLORS_PER_TABLE)
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color_octet_index = 0;
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color_table_index = COCTET * s->buf[stream_ptr++];
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For this input of 6 hex bytes:
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Mangle it to this output:
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flags_a = xx012456, flags_b = xx89A37B
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/* build the color flags */
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color_flags_a = color_flags_b = 0;
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(s->buf[stream_ptr + 0] << 16) |
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((s->buf[stream_ptr + 1] & 0xF0) << 8) |
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((s->buf[stream_ptr + 2] & 0xF0) << 4) |
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((s->buf[stream_ptr + 2] & 0x0F) << 4) |
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((s->buf[stream_ptr + 3] & 0xF0) >> 4);
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(s->buf[stream_ptr + 4] << 16) |
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((s->buf[stream_ptr + 5] & 0xF0) << 8) |
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((s->buf[stream_ptr + 1] & 0x0F) << 8) |
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((s->buf[stream_ptr + 3] & 0x0F) << 4) |
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(s->buf[stream_ptr + 5] & 0x0F);
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color_flags = color_flags_a;
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/* flag mask actually acts as a bit shift count here */
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block_ptr = row_ptr + pixel_ptr;
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for (pixel_y = 0; pixel_y < 4; pixel_y++) {
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/* reload flags at third row (iteration pixel_y == 2) */
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color_flags = color_flags_b;
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for (pixel_x = 0; pixel_x < 4; pixel_x++) {
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pixel = color_table_index +
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((color_flags >> flag_mask) & 0x07);
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pixels[block_ptr++] = s->color_octets[pixel];
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block_ptr += row_inc;
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/* 16-color block encoding (every pixel is a different color) */
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n_blocks = (opcode & 0x0F) + 1;
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block_ptr = row_ptr + pixel_ptr;
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for (pixel_y = 0; pixel_y < 4; pixel_y++) {
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for (pixel_x = 0; pixel_x < 4; pixel_x++) {
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pixels[block_ptr++] = s->buf[stream_ptr++];
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block_ptr += row_inc;
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av_log(s->avctx, AV_LOG_INFO, "0xF0 opcode seen in SMC chunk (contact the developers)\n");
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static int smc_decode_init(AVCodecContext *avctx)
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SmcContext *s = (SmcContext *)avctx->priv_data;
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avctx->pix_fmt = PIX_FMT_PAL8;
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avctx->has_b_frames = 0;
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dsputil_init(&s->dsp, avctx);
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s->frame.data[0] = NULL;
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static int smc_decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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uint8_t *buf, int buf_size)
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SmcContext *s = (SmcContext *)avctx->priv_data;
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s->frame.reference = 1;
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s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
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FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
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if (avctx->reget_buffer(avctx, &s->frame)) {
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av_log(s->avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
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smc_decode_stream(s);
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*data_size = sizeof(AVFrame);
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*(AVFrame*)data = s->frame;
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/* always report that the buffer was completely consumed */
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static int smc_decode_end(AVCodecContext *avctx)
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SmcContext *s = (SmcContext *)avctx->priv_data;
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if (s->frame.data[0])
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avctx->release_buffer(avctx, &s->frame);
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AVCodec smc_decoder = {
added
removed
adm_lavcodec/smc.c
