/* * Interplay C93 video decoder * Copyright (c) 2007 Anssi Hannula * * This file is part of Libav. * * Libav 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. * * Libav 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 Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "avcodec.h" #include "bytestream.h" #include "internal.h" typedef struct C93DecoderContext { AVFrame *pictures[2]; int currentpic; } C93DecoderContext; typedef enum { C93_8X8_FROM_PREV = 0x02, C93_4X4_FROM_PREV = 0x06, C93_4X4_FROM_CURR = 0x07, C93_8X8_2COLOR = 0x08, C93_4X4_2COLOR = 0x0A, C93_4X4_4COLOR_GRP = 0x0B, C93_4X4_4COLOR = 0x0D, C93_NOOP = 0x0E, C93_8X8_INTRA = 0x0F, } C93BlockType; #define WIDTH 320 #define HEIGHT 192 #define C93_HAS_PALETTE 0x01 #define C93_FIRST_FRAME 0x02 static av_cold int decode_end(AVCodecContext *avctx) { C93DecoderContext * const c93 = avctx->priv_data; av_frame_free(&c93->pictures[0]); av_frame_free(&c93->pictures[1]); return 0; } static av_cold int decode_init(AVCodecContext *avctx) { C93DecoderContext *s = avctx->priv_data; avctx->pix_fmt = AV_PIX_FMT_PAL8; s->pictures[0] = av_frame_alloc(); s->pictures[1] = av_frame_alloc(); if (!s->pictures[0] || !s->pictures[1]) { decode_end(avctx); return AVERROR(ENOMEM); } return 0; } static inline int copy_block(AVCodecContext *avctx, uint8_t *to, uint8_t *from, int offset, int height, int stride) { int i; int width = height; int from_x = offset % WIDTH; int from_y = offset / WIDTH; int overflow = from_x + width - WIDTH; if (!from) { /* silently ignoring predictive blocks in first frame */ return 0; } if (from_y + height > HEIGHT) { av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n", offset); return AVERROR_INVALIDDATA; } if (overflow > 0) { width -= overflow; for (i = 0; i < height; i++) { memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow); } } for (i = 0; i < height; i++) { memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width); } return 0; } static inline void draw_n_color(uint8_t *out, int stride, int width, int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col) { int x, y; for (y = 0; y < height; y++) { if (grps) cols[0] = grps[3 * (y >> 1)]; for (x = 0; x < width; x++) { if (grps) cols[1]= grps[(x >> 1) + 1]; out[x + y*stride] = cols[col & ((1 << bpp) - 1)]; col >>= bpp; } } } static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt) { const uint8_t *buf = avpkt->data; int buf_size = avpkt->size; C93DecoderContext * const c93 = avctx->priv_data; AVFrame * const newpic = c93->pictures[c93->currentpic]; AVFrame * const oldpic = c93->pictures[c93->currentpic^1]; GetByteContext gb; uint8_t *out; int stride, ret, i, x, y, b, bt = 0; c93->currentpic ^= 1; if ((ret = ff_reget_buffer(avctx, newpic)) < 0) { av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n"); return ret; } stride = newpic->linesize[0]; bytestream2_init(&gb, buf, buf_size); b = bytestream2_get_byte(&gb); if (b & C93_FIRST_FRAME) { newpic->pict_type = AV_PICTURE_TYPE_I; newpic->key_frame = 1; } else { newpic->pict_type = AV_PICTURE_TYPE_P; newpic->key_frame = 0; } for (y = 0; y < HEIGHT; y += 8) { out = newpic->data[0] + y * stride; for (x = 0; x < WIDTH; x += 8) { uint8_t *copy_from = oldpic->data[0]; unsigned int offset, j; uint8_t cols[4], grps[4]; C93BlockType block_type; if (!bt) bt = bytestream2_get_byte(&gb); block_type= bt & 0x0F; switch (block_type) { case C93_8X8_FROM_PREV: offset = bytestream2_get_le16(&gb); if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0) return ret; break; case C93_4X4_FROM_CURR: copy_from = newpic->data[0]; case C93_4X4_FROM_PREV: for (j = 0; j < 8; j += 4) { for (i = 0; i < 8; i += 4) { offset = bytestream2_get_le16(&gb); if ((ret = copy_block(avctx, &out[j*stride+i], copy_from, offset, 4, stride)) < 0) return ret; } } break; case C93_8X8_2COLOR: bytestream2_get_buffer(&gb, cols, 2); for (i = 0; i < 8; i++) { draw_n_color(out + i*stride, stride, 8, 1, 1, cols, NULL, bytestream2_get_byte(&gb)); } break; case C93_4X4_2COLOR: case C93_4X4_4COLOR: case C93_4X4_4COLOR_GRP: for (j = 0; j < 8; j += 4) { for (i = 0; i < 8; i += 4) { if (block_type == C93_4X4_2COLOR) { bytestream2_get_buffer(&gb, cols, 2); draw_n_color(out + i + j*stride, stride, 4, 4, 1, cols, NULL, bytestream2_get_le16(&gb)); } else if (block_type == C93_4X4_4COLOR) { bytestream2_get_buffer(&gb, cols, 4); draw_n_color(out + i + j*stride, stride, 4, 4, 2, cols, NULL, bytestream2_get_le32(&gb)); } else { bytestream2_get_buffer(&gb, grps, 4); draw_n_color(out + i + j*stride, stride, 4, 4, 1, cols, grps, bytestream2_get_le16(&gb)); } } } break; case C93_NOOP: break; case C93_8X8_INTRA: for (j = 0; j < 8; j++) bytestream2_get_buffer(&gb, out + j*stride, 8); break; default: av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n", block_type, x, y); return AVERROR_INVALIDDATA; } bt >>= 4; out += 8; } } if (b & C93_HAS_PALETTE) { uint32_t *palette = (uint32_t *) newpic->data[1]; for (i = 0; i < 256; i++) { palette[i] = bytestream2_get_be24(&gb); } newpic->palette_has_changed = 1; } else { if (oldpic->data[1]) memcpy(newpic->data[1], oldpic->data[1], 256 * 4); } if ((ret = av_frame_ref(data, newpic)) < 0) return ret; *got_frame = 1; return buf_size; } AVCodec ff_c93_decoder = { .name = "c93", .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"), .type = AVMEDIA_TYPE_VIDEO, .id = AV_CODEC_ID_C93, .priv_data_size = sizeof(C93DecoderContext), .init = decode_init, .close = decode_end, .decode = decode_frame, .capabilities = AV_CODEC_CAP_DR1, };