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libavcodec/bethsoftvideo.c

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00001 /*
00002  * Bethesda VID video decoder
00003  * Copyright (C) 2007 Nicholas Tung
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 
00030 #include "libavutil/common.h"
00031 #include "dsputil.h"
00032 #include "bethsoftvideo.h"
00033 #include "bytestream.h"
00034 
00035 typedef struct BethsoftvidContext {
00036     AVFrame frame;
00037 } BethsoftvidContext;
00038 
00039 static av_cold int bethsoftvid_decode_init(AVCodecContext *avctx)
00040 {
00041     BethsoftvidContext *vid = avctx->priv_data;
00042     avcodec_get_frame_defaults(&vid->frame);
00043     vid->frame.reference = 1;
00044     vid->frame.buffer_hints = FF_BUFFER_HINTS_VALID |
00045         FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
00046     avctx->pix_fmt = PIX_FMT_PAL8;
00047     return 0;
00048 }
00049 
00050 static void set_palette(AVFrame * frame, const uint8_t * palette_buffer)
00051 {
00052     uint32_t * palette = (uint32_t *)frame->data[1];
00053     int a;
00054     for(a = 0; a < 256; a++){
00055         palette[a] = AV_RB24(&palette_buffer[a * 3]) * 4;
00056     }
00057     frame->palette_has_changed = 1;
00058 }
00059 
00060 static int bethsoftvid_decode_frame(AVCodecContext *avctx,
00061                               void *data, int *data_size,
00062                               AVPacket *avpkt)
00063 {
00064     const uint8_t *buf = avpkt->data;
00065     int buf_size = avpkt->size;
00066     BethsoftvidContext * vid = avctx->priv_data;
00067     char block_type;
00068     uint8_t * dst;
00069     uint8_t * frame_end;
00070     int remaining = avctx->width;          // number of bytes remaining on a line
00071     const int wrap_to_next_line = vid->frame.linesize[0] - avctx->width;
00072     int code;
00073     int yoffset;
00074 
00075     if (avctx->reget_buffer(avctx, &vid->frame)) {
00076         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
00077         return -1;
00078     }
00079     dst = vid->frame.data[0];
00080     frame_end = vid->frame.data[0] + vid->frame.linesize[0] * avctx->height;
00081 
00082     switch(block_type = *buf++){
00083         case PALETTE_BLOCK:
00084             set_palette(&vid->frame, buf);
00085             return 0;
00086         case VIDEO_YOFF_P_FRAME:
00087             yoffset = bytestream_get_le16(&buf);
00088             if(yoffset >= avctx->height)
00089                 return -1;
00090             dst += vid->frame.linesize[0] * yoffset;
00091     }
00092 
00093     // main code
00094     while((code = *buf++)){
00095         int length = code & 0x7f;
00096 
00097         // copy any bytes starting at the current position, and ending at the frame width
00098         while(length > remaining){
00099             if(code < 0x80)
00100                 bytestream_get_buffer(&buf, dst, remaining);
00101             else if(block_type == VIDEO_I_FRAME)
00102                 memset(dst, buf[0], remaining);
00103             length -= remaining;      // decrement the number of bytes to be copied
00104             dst += remaining + wrap_to_next_line;    // skip over extra bytes at end of frame
00105             remaining = avctx->width;
00106             if(dst == frame_end)
00107                 goto end;
00108         }
00109 
00110         // copy any remaining bytes after / if line overflows
00111         if(code < 0x80)
00112             bytestream_get_buffer(&buf, dst, length);
00113         else if(block_type == VIDEO_I_FRAME)
00114             memset(dst, *buf++, length);
00115         remaining -= length;
00116         dst += length;
00117     }
00118     end:
00119 
00120     *data_size = sizeof(AVFrame);
00121     *(AVFrame*)data = vid->frame;
00122 
00123     return buf_size;
00124 }
00125 
00126 static av_cold int bethsoftvid_decode_end(AVCodecContext *avctx)
00127 {
00128     BethsoftvidContext * vid = avctx->priv_data;
00129     if(vid->frame.data[0])
00130         avctx->release_buffer(avctx, &vid->frame);
00131     return 0;
00132 }
00133 
00134 AVCodec ff_bethsoftvid_decoder = {
00135     .name = "bethsoftvid",
00136     .type = AVMEDIA_TYPE_VIDEO,
00137     .id = CODEC_ID_BETHSOFTVID,
00138     .priv_data_size = sizeof(BethsoftvidContext),
00139     .init = bethsoftvid_decode_init,
00140     .close = bethsoftvid_decode_end,
00141     .decode = bethsoftvid_decode_frame,
00142     .capabilities = CODEC_CAP_DR1,
00143     .long_name = NULL_IF_CONFIG_SMALL("Bethesda VID video"),
00144 };

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