libavcodec/bfi.c
Go to the documentation of this file.
00001 /*
00002  * Brute Force & Ignorance (BFI) video decoder
00003  * Copyright (c) 2008 Sisir Koppaka
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00029 #include "libavutil/common.h"
00030 #include "avcodec.h"
00031 #include "bytestream.h"
00032 
00033 typedef struct BFIContext {
00034     AVCodecContext *avctx;
00035     AVFrame frame;
00036     uint8_t *dst;
00037     uint32_t pal[256];
00038 } BFIContext;
00039 
00040 static av_cold int bfi_decode_init(AVCodecContext *avctx)
00041 {
00042     BFIContext *bfi = avctx->priv_data;
00043     avctx->pix_fmt = PIX_FMT_PAL8;
00044     avcodec_get_frame_defaults(&bfi->frame);
00045     bfi->dst = av_mallocz(avctx->width * avctx->height);
00046     return 0;
00047 }
00048 
00049 static int bfi_decode_frame(AVCodecContext *avctx, void *data,
00050                             int *data_size, AVPacket *avpkt)
00051 {
00052     GetByteContext g;
00053     int buf_size = avpkt->size;
00054     BFIContext *bfi = avctx->priv_data;
00055     uint8_t *dst = bfi->dst;
00056     uint8_t *src, *dst_offset, colour1, colour2;
00057     uint8_t *frame_end = bfi->dst + avctx->width * avctx->height;
00058     uint32_t *pal;
00059     int i, j, height = avctx->height;
00060 
00061     if (bfi->frame.data[0])
00062         avctx->release_buffer(avctx, &bfi->frame);
00063 
00064     bfi->frame.reference = 3;
00065 
00066     if (avctx->get_buffer(avctx, &bfi->frame) < 0) {
00067         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00068         return -1;
00069     }
00070 
00071     bytestream2_init(&g, avpkt->data, buf_size);
00072 
00073     /* Set frame parameters and palette, if necessary */
00074     if (!avctx->frame_number) {
00075         bfi->frame.pict_type = AV_PICTURE_TYPE_I;
00076         bfi->frame.key_frame = 1;
00077         /* Setting the palette */
00078         if (avctx->extradata_size > 768) {
00079             av_log(NULL, AV_LOG_ERROR, "Palette is too large.\n");
00080             return -1;
00081         }
00082         pal = (uint32_t *)bfi->frame.data[1];
00083         for (i = 0; i < avctx->extradata_size / 3; i++) {
00084             int shift = 16;
00085             *pal = 0xFF << 24;
00086             for (j = 0; j < 3; j++, shift -= 8)
00087                 *pal +=
00088                     ((avctx->extradata[i * 3 + j] << 2) |
00089                     (avctx->extradata[i * 3 + j] >> 4)) << shift;
00090             pal++;
00091         }
00092         memcpy(bfi->pal, bfi->frame.data[1], sizeof(bfi->pal));
00093         bfi->frame.palette_has_changed = 1;
00094     } else {
00095         bfi->frame.pict_type = AV_PICTURE_TYPE_P;
00096         bfi->frame.key_frame = 0;
00097         bfi->frame.palette_has_changed = 0;
00098         memcpy(bfi->frame.data[1], bfi->pal, sizeof(bfi->pal));
00099     }
00100 
00101     bytestream2_skip(&g, 4); // Unpacked size, not required.
00102 
00103     while (dst != frame_end) {
00104         static const uint8_t lentab[4] = { 0, 2, 0, 1 };
00105         unsigned int byte   = bytestream2_get_byte(&g), av_uninit(offset);
00106         unsigned int code   = byte >> 6;
00107         unsigned int length = byte & ~0xC0;
00108 
00109         if (!bytestream2_get_bytes_left(&g)) {
00110             av_log(avctx, AV_LOG_ERROR,
00111                    "Input resolution larger than actual frame.\n");
00112             return -1;
00113         }
00114 
00115         /* Get length and offset(if required) */
00116         if (length == 0) {
00117             if (code == 1) {
00118                 length = bytestream2_get_byte(&g);
00119                 offset = bytestream2_get_le16(&g);
00120             } else {
00121                 length = bytestream2_get_le16(&g);
00122                 if (code == 2 && length == 0)
00123                     break;
00124             }
00125         } else {
00126             if (code == 1)
00127                 offset = bytestream2_get_byte(&g);
00128         }
00129 
00130         /* Do boundary check */
00131         if (dst + (length << lentab[code]) > frame_end)
00132             break;
00133 
00134         switch (code) {
00135 
00136         case 0:                //Normal Chain
00137             if (length >= bytestream2_get_bytes_left(&g)) {
00138                 av_log(avctx, AV_LOG_ERROR, "Frame larger than buffer.\n");
00139                 return -1;
00140             }
00141             bytestream2_get_buffer(&g, dst, length);
00142             dst += length;
00143             break;
00144 
00145         case 1:                //Back Chain
00146             dst_offset = dst - offset;
00147             length *= 4;        //Convert dwords to bytes.
00148             if (dst_offset < bfi->dst)
00149                 break;
00150             while (length--)
00151                 *dst++ = *dst_offset++;
00152             break;
00153 
00154         case 2:                //Skip Chain
00155             dst += length;
00156             break;
00157 
00158         case 3:                //Fill Chain
00159             colour1 = bytestream2_get_byte(&g);
00160             colour2 = bytestream2_get_byte(&g);
00161             while (length--) {
00162                 *dst++ = colour1;
00163                 *dst++ = colour2;
00164             }
00165             break;
00166 
00167         }
00168     }
00169 
00170     src = bfi->dst;
00171     dst = bfi->frame.data[0];
00172     while (height--) {
00173         memcpy(dst, src, avctx->width);
00174         src += avctx->width;
00175         dst += bfi->frame.linesize[0];
00176     }
00177     *data_size = sizeof(AVFrame);
00178     *(AVFrame *)data = bfi->frame;
00179     return buf_size;
00180 }
00181 
00182 static av_cold int bfi_decode_close(AVCodecContext * avctx)
00183 {
00184     BFIContext *bfi = avctx->priv_data;
00185     if (bfi->frame.data[0])
00186         avctx->release_buffer(avctx, &bfi->frame);
00187     av_free(bfi->dst);
00188     return 0;
00189 }
00190 
00191 AVCodec ff_bfi_decoder = {
00192     .name = "bfi",
00193     .type = AVMEDIA_TYPE_VIDEO,
00194     .id = CODEC_ID_BFI,
00195     .priv_data_size = sizeof(BFIContext),
00196     .init = bfi_decode_init,
00197     .close = bfi_decode_close,
00198     .decode = bfi_decode_frame,
00199     .capabilities = CODEC_CAP_DR1,
00200     .long_name = NULL_IF_CONFIG_SMALL("Brute Force & Ignorance"),
00201 };