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libavcodec/mmvideo.c

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00001 /*
00002  * American Laser Games MM Video Decoder
00003  * Copyright (c) 2006,2008 Peter Ross
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 
00034 #include "libavutil/intreadwrite.h"
00035 #include "avcodec.h"
00036 #include "bytestream.h"
00037 
00038 #define MM_PREAMBLE_SIZE    6
00039 
00040 #define MM_TYPE_INTER       0x5
00041 #define MM_TYPE_INTRA       0x8
00042 #define MM_TYPE_INTRA_HH    0xc
00043 #define MM_TYPE_INTER_HH    0xd
00044 #define MM_TYPE_INTRA_HHV   0xe
00045 #define MM_TYPE_INTER_HHV   0xf
00046 #define MM_TYPE_PALETTE     0x31
00047 
00048 typedef struct MmContext {
00049     AVCodecContext *avctx;
00050     AVFrame frame;
00051     int palette[AVPALETTE_COUNT];
00052     GetByteContext gb;
00053 } MmContext;
00054 
00055 static av_cold int mm_decode_init(AVCodecContext *avctx)
00056 {
00057     MmContext *s = avctx->priv_data;
00058 
00059     s->avctx = avctx;
00060 
00061     avctx->pix_fmt = PIX_FMT_PAL8;
00062 
00063     s->frame.reference = 1;
00064 
00065     return 0;
00066 }
00067 
00068 static int mm_decode_pal(MmContext *s)
00069 {
00070     int i;
00071 
00072     bytestream2_skip(&s->gb, 4);
00073     for (i = 0; i < 128; i++) {
00074         s->palette[i] = bytestream2_get_be24(&s->gb);
00075         s->palette[i+128] = s->palette[i]<<2;
00076     }
00077 
00078     return 0;
00079 }
00080 
00085 static int mm_decode_intra(MmContext * s, int half_horiz, int half_vert)
00086 {
00087     int i, x, y;
00088     i=0; x=0; y=0;
00089 
00090     while (bytestream2_get_bytes_left(&s->gb) > 0) {
00091         int run_length, color;
00092 
00093         if (y >= s->avctx->height)
00094             return 0;
00095 
00096         color = bytestream2_get_byte(&s->gb);
00097         if (color & 0x80) {
00098             run_length = 1;
00099         }else{
00100             run_length = (color & 0x7f) + 2;
00101             color = bytestream2_get_byte(&s->gb);
00102         }
00103 
00104         if (half_horiz)
00105             run_length *=2;
00106 
00107         if (color) {
00108             memset(s->frame.data[0] + y*s->frame.linesize[0] + x, color, run_length);
00109             if (half_vert)
00110                 memset(s->frame.data[0] + (y+1)*s->frame.linesize[0] + x, color, run_length);
00111         }
00112         x+= run_length;
00113 
00114         if (x >= s->avctx->width) {
00115             x=0;
00116             y += 1 + half_vert;
00117         }
00118     }
00119 
00120     return 0;
00121 }
00122 
00123 /*
00124  * @param half_horiz Half horizontal resolution (0 or 1)
00125  * @param half_vert Half vertical resolution (0 or 1)
00126  */
00127 static int mm_decode_inter(MmContext * s, int half_horiz, int half_vert)
00128 {
00129     int data_off = bytestream2_get_le16(&s->gb), y;
00130     GetByteContext data_ptr;
00131 
00132     if (bytestream2_get_bytes_left(&s->gb) < data_off)
00133         return AVERROR_INVALIDDATA;
00134 
00135     bytestream2_init(&data_ptr, s->gb.buffer + data_off, bytestream2_get_bytes_left(&s->gb) - data_off);
00136     while (s->gb.buffer < data_ptr.buffer_start) {
00137         int i, j;
00138         int length = bytestream2_get_byte(&s->gb);
00139         int x = bytestream2_get_byte(&s->gb) + ((length & 0x80) << 1);
00140         length &= 0x7F;
00141 
00142         if (length==0) {
00143             y += x;
00144             continue;
00145         }
00146 
00147         if (y + half_vert >= s->avctx->height)
00148             return 0;
00149 
00150         for(i=0; i<length; i++) {
00151             int replace_array = bytestream2_get_byte(&s->gb);
00152             for(j=0; j<8; j++) {
00153                 int replace = (replace_array >> (7-j)) & 1;
00154                 if (replace) {
00155                     int color = bytestream2_get_byte(&data_ptr);
00156                     s->frame.data[0][y*s->frame.linesize[0] + x] = color;
00157                     if (half_horiz)
00158                         s->frame.data[0][y*s->frame.linesize[0] + x + 1] = color;
00159                     if (half_vert) {
00160                         s->frame.data[0][(y+1)*s->frame.linesize[0] + x] = color;
00161                         if (half_horiz)
00162                             s->frame.data[0][(y+1)*s->frame.linesize[0] + x + 1] = color;
00163                     }
00164                 }
00165                 x += 1 + half_horiz;
00166             }
00167         }
00168 
00169         y += 1 + half_vert;
00170     }
00171 
00172     return 0;
00173 }
00174 
00175 static int mm_decode_frame(AVCodecContext *avctx,
00176                             void *data, int *data_size,
00177                             AVPacket *avpkt)
00178 {
00179     const uint8_t *buf = avpkt->data;
00180     int buf_size = avpkt->size;
00181     MmContext *s = avctx->priv_data;
00182     int type, res;
00183 
00184     if (buf_size < MM_PREAMBLE_SIZE)
00185         return AVERROR_INVALIDDATA;
00186     type = AV_RL16(&buf[0]);
00187     buf += MM_PREAMBLE_SIZE;
00188     buf_size -= MM_PREAMBLE_SIZE;
00189     bytestream2_init(&s->gb, buf, buf_size);
00190 
00191     if (avctx->reget_buffer(avctx, &s->frame) < 0) {
00192         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
00193         return -1;
00194     }
00195 
00196     switch(type) {
00197     case MM_TYPE_PALETTE   : res = mm_decode_pal(s); return buf_size;
00198     case MM_TYPE_INTRA     : res = mm_decode_intra(s, 0, 0); break;
00199     case MM_TYPE_INTRA_HH  : res = mm_decode_intra(s, 1, 0); break;
00200     case MM_TYPE_INTRA_HHV : res = mm_decode_intra(s, 1, 1); break;
00201     case MM_TYPE_INTER     : res = mm_decode_inter(s, 0, 0); break;
00202     case MM_TYPE_INTER_HH  : res = mm_decode_inter(s, 1, 0); break;
00203     case MM_TYPE_INTER_HHV : res = mm_decode_inter(s, 1, 1); break;
00204     default:
00205         res = AVERROR_INVALIDDATA;
00206         break;
00207     }
00208     if (res < 0)
00209         return res;
00210 
00211     memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
00212 
00213     *data_size = sizeof(AVFrame);
00214     *(AVFrame*)data = s->frame;
00215 
00216     return buf_size;
00217 }
00218 
00219 static av_cold int mm_decode_end(AVCodecContext *avctx)
00220 {
00221     MmContext *s = avctx->priv_data;
00222 
00223     if(s->frame.data[0])
00224         avctx->release_buffer(avctx, &s->frame);
00225 
00226     return 0;
00227 }
00228 
00229 AVCodec ff_mmvideo_decoder = {
00230     .name           = "mmvideo",
00231     .type           = AVMEDIA_TYPE_VIDEO,
00232     .id             = CODEC_ID_MMVIDEO,
00233     .priv_data_size = sizeof(MmContext),
00234     .init           = mm_decode_init,
00235     .close          = mm_decode_end,
00236     .decode         = mm_decode_frame,
00237     .capabilities   = CODEC_CAP_DR1,
00238     .long_name = NULL_IF_CONFIG_SMALL("American Laser Games MM Video"),
00239 };
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