libavcodec/avs.c
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00001 /*
00002  * AVS video decoder.
00003  * Copyright (c) 2006  Aurelien Jacobs <aurel@gnuage.org>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avcodec.h"
00023 #include "get_bits.h"
00024 
00025 
00026 typedef struct {
00027     AVFrame picture;
00028 } AvsContext;
00029 
00030 typedef enum {
00031     AVS_VIDEO     = 0x01,
00032     AVS_AUDIO     = 0x02,
00033     AVS_PALETTE   = 0x03,
00034     AVS_GAME_DATA = 0x04,
00035 } AvsBlockType;
00036 
00037 typedef enum {
00038     AVS_I_FRAME     = 0x00,
00039     AVS_P_FRAME_3X3 = 0x01,
00040     AVS_P_FRAME_2X2 = 0x02,
00041     AVS_P_FRAME_2X3 = 0x03,
00042 } AvsVideoSubType;
00043 
00044 
00045 static int
00046 avs_decode_frame(AVCodecContext * avctx,
00047                  void *data, int *data_size, AVPacket *avpkt)
00048 {
00049     const uint8_t *buf = avpkt->data;
00050     const uint8_t *buf_end = avpkt->data + avpkt->size;
00051     int buf_size = avpkt->size;
00052     AvsContext *const avs = avctx->priv_data;
00053     AVFrame *picture = data;
00054     AVFrame *const p = (AVFrame *) & avs->picture;
00055     const uint8_t *table, *vect;
00056     uint8_t *out;
00057     int i, j, x, y, stride, vect_w = 3, vect_h = 3;
00058     AvsVideoSubType sub_type;
00059     AvsBlockType type;
00060     GetBitContext change_map;
00061 
00062     if (avctx->reget_buffer(avctx, p)) {
00063         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
00064         return -1;
00065     }
00066     p->reference = 1;
00067     p->pict_type = AV_PICTURE_TYPE_P;
00068     p->key_frame = 0;
00069 
00070     out = avs->picture.data[0];
00071     stride = avs->picture.linesize[0];
00072 
00073     if (buf_end - buf < 4)
00074         return AVERROR_INVALIDDATA;
00075     sub_type = buf[0];
00076     type = buf[1];
00077     buf += 4;
00078 
00079     if (type == AVS_PALETTE) {
00080         int first, last;
00081         uint32_t *pal = (uint32_t *) avs->picture.data[1];
00082 
00083         first = AV_RL16(buf);
00084         last = first + AV_RL16(buf + 2);
00085         if (first >= 256 || last > 256 || buf_end - buf < 4 + 4 + 3 * (last - first))
00086             return AVERROR_INVALIDDATA;
00087         buf += 4;
00088         for (i=first; i<last; i++, buf+=3)
00089             pal[i] = (buf[0] << 18) | (buf[1] << 10) | (buf[2] << 2);
00090 
00091         sub_type = buf[0];
00092         type = buf[1];
00093         buf += 4;
00094     }
00095 
00096     if (type != AVS_VIDEO)
00097         return -1;
00098 
00099     switch (sub_type) {
00100     case AVS_I_FRAME:
00101         p->pict_type = AV_PICTURE_TYPE_I;
00102         p->key_frame = 1;
00103     case AVS_P_FRAME_3X3:
00104         vect_w = 3;
00105         vect_h = 3;
00106         break;
00107 
00108     case AVS_P_FRAME_2X2:
00109         vect_w = 2;
00110         vect_h = 2;
00111         break;
00112 
00113     case AVS_P_FRAME_2X3:
00114         vect_w = 2;
00115         vect_h = 3;
00116         break;
00117 
00118     default:
00119       return -1;
00120     }
00121 
00122     if (buf_end - buf < 256 * vect_w * vect_h)
00123         return AVERROR_INVALIDDATA;
00124     table = buf + (256 * vect_w * vect_h);
00125     if (sub_type != AVS_I_FRAME) {
00126         int map_size = ((318 / vect_w + 7) / 8) * (198 / vect_h);
00127         if (buf_end - table < map_size)
00128             return AVERROR_INVALIDDATA;
00129         init_get_bits(&change_map, table, map_size * 8);
00130         table += map_size;
00131     }
00132 
00133     for (y=0; y<198; y+=vect_h) {
00134         for (x=0; x<318; x+=vect_w) {
00135             if (sub_type == AVS_I_FRAME || get_bits1(&change_map)) {
00136                 if (buf_end - table < 1)
00137                     return AVERROR_INVALIDDATA;
00138                 vect = &buf[*table++ * (vect_w * vect_h)];
00139                 for (j=0; j<vect_w; j++) {
00140                     out[(y + 0) * stride + x + j] = vect[(0 * vect_w) + j];
00141                     out[(y + 1) * stride + x + j] = vect[(1 * vect_w) + j];
00142                     if (vect_h == 3)
00143                         out[(y + 2) * stride + x + j] =
00144                             vect[(2 * vect_w) + j];
00145                 }
00146             }
00147         }
00148         if (sub_type != AVS_I_FRAME)
00149             align_get_bits(&change_map);
00150     }
00151 
00152     *picture = *(AVFrame *) & avs->picture;
00153     *data_size = sizeof(AVPicture);
00154 
00155     return buf_size;
00156 }
00157 
00158 static av_cold int avs_decode_init(AVCodecContext * avctx)
00159 {
00160     avctx->pix_fmt = PIX_FMT_PAL8;
00161     avcodec_set_dimensions(avctx, 318, 198);
00162     return 0;
00163 }
00164 
00165 static av_cold int avs_decode_end(AVCodecContext *avctx)
00166 {
00167     AvsContext *s = avctx->priv_data;
00168     if (s->picture.data[0])
00169         avctx->release_buffer(avctx, &s->picture);
00170     return 0;
00171 }
00172 
00173 
00174 AVCodec ff_avs_decoder = {
00175     .name           = "avs",
00176     .type           = AVMEDIA_TYPE_VIDEO,
00177     .id             = CODEC_ID_AVS,
00178     .priv_data_size = sizeof(AvsContext),
00179     .init           = avs_decode_init,
00180     .decode         = avs_decode_frame,
00181     .close          = avs_decode_end,
00182     .capabilities   = CODEC_CAP_DR1,
00183     .long_name = NULL_IF_CONFIG_SMALL("AVS (Audio Video Standard) video"),
00184 };