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libavcodec/flashsv.c

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00001 /*
00002  * Flash Screen Video decoder
00003  * Copyright (C) 2004 Alex Beregszaszi
00004  * Copyright (C) 2006 Benjamin Larsson
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00030 /* Bitstream description
00031  * The picture is divided into blocks that are zlib compressed.
00032  *
00033  * The decoder is fed complete frames, the frameheader contains:
00034  * 4bits of block width
00035  * 12bits of frame width
00036  * 4bits of block height
00037  * 12bits of frame height
00038  *
00039  * Directly after the header are the compressed blocks. The blocks
00040  * have their compressed size represented with 16bits in the beginnig.
00041  * If the size = 0 then the block is unchanged from the previous frame.
00042  * All blocks are decompressed until the buffer is consumed.
00043  *
00044  * Encoding ideas, a basic encoder would just use a fixed block size.
00045  * Block sizes can be multipels of 16, from 16 to 256. The blocks don't
00046  * have to be quadratic. A brute force search with a set of diffrent
00047  * block sizes should give a better result then to just use a fixed size.
00048  */
00049 
00050 #include <stdio.h>
00051 #include <stdlib.h>
00052 
00053 #include "avcodec.h"
00054 #include "get_bits.h"
00055 
00056 #include <zlib.h>
00057 
00058 typedef struct FlashSVContext {
00059     AVCodecContext *avctx;
00060     AVFrame frame;
00061     int image_width, image_height;
00062     int block_width, block_height;
00063     uint8_t* tmpblock;
00064     int block_size;
00065     z_stream zstream;
00066 } FlashSVContext;
00067 
00068 
00069 static void copy_region(uint8_t *sptr, uint8_t *dptr,
00070         int dx, int dy, int h, int w, int stride)
00071 {
00072     int i;
00073 
00074     for (i = dx+h; i > dx; i--)
00075     {
00076         memcpy(dptr+(i*stride)+dy*3, sptr, w*3);
00077         sptr += w*3;
00078     }
00079 }
00080 
00081 
00082 static av_cold int flashsv_decode_init(AVCodecContext *avctx)
00083 {
00084     FlashSVContext *s = avctx->priv_data;
00085     int zret; // Zlib return code
00086 
00087     s->avctx = avctx;
00088     s->zstream.zalloc = Z_NULL;
00089     s->zstream.zfree = Z_NULL;
00090     s->zstream.opaque = Z_NULL;
00091     zret = inflateInit(&(s->zstream));
00092     if (zret != Z_OK) {
00093         av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
00094         return 1;
00095     }
00096     avctx->pix_fmt = PIX_FMT_BGR24;
00097     s->frame.data[0] = NULL;
00098 
00099     return 0;
00100 }
00101 
00102 
00103 static int flashsv_decode_frame(AVCodecContext *avctx,
00104                                     void *data, int *data_size,
00105                                     AVPacket *avpkt)
00106 {
00107     const uint8_t *buf = avpkt->data;
00108     int buf_size = avpkt->size;
00109     FlashSVContext *s = avctx->priv_data;
00110     int h_blocks, v_blocks, h_part, v_part, i, j;
00111     GetBitContext gb;
00112 
00113     /* no supplementary picture */
00114     if (buf_size == 0)
00115         return 0;
00116     if (buf_size < 4)
00117         return -1;
00118 
00119     init_get_bits(&gb, buf, buf_size * 8);
00120 
00121     /* start to parse the bitstream */
00122     s->block_width = 16* (get_bits(&gb, 4)+1);
00123     s->image_width =     get_bits(&gb,12);
00124     s->block_height= 16* (get_bits(&gb, 4)+1);
00125     s->image_height=     get_bits(&gb,12);
00126 
00127     /* calculate amount of blocks and the size of the border blocks */
00128     h_blocks = s->image_width / s->block_width;
00129     h_part = s->image_width % s->block_width;
00130     v_blocks = s->image_height / s->block_height;
00131     v_part = s->image_height % s->block_height;
00132 
00133     /* the block size could change between frames, make sure the buffer
00134      * is large enough, if not, get a larger one */
00135     if(s->block_size < s->block_width*s->block_height) {
00136         if (s->tmpblock != NULL)
00137             av_free(s->tmpblock);
00138         if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) {
00139             av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
00140             return -1;
00141         }
00142     }
00143     s->block_size = s->block_width*s->block_height;
00144 
00145     /* init the image size once */
00146     if((avctx->width==0) && (avctx->height==0)){
00147         avctx->width = s->image_width;
00148         avctx->height = s->image_height;
00149     }
00150 
00151     /* check for changes of image width and image height */
00152     if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
00153         av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
00154         av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d  vs  ch = %d, cv = %d\n",avctx->height,
00155         avctx->width,s->image_height,s->image_width);
00156         return -1;
00157     }
00158 
00159     av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
00160         s->image_width, s->image_height, s->block_width, s->block_height,
00161         h_blocks, v_blocks, h_part, v_part);
00162 
00163     s->frame.reference = 1;
00164     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
00165     if(avctx->reget_buffer(avctx, &s->frame) < 0){
00166       av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
00167       return -1;
00168     }
00169 
00170     /* loop over all block columns */
00171     for (j = 0; j < v_blocks + (v_part?1:0); j++)
00172     {
00173 
00174         int hp = j*s->block_height; // horiz position in frame
00175         int hs = (j<v_blocks)?s->block_height:v_part; // size of block
00176 
00177 
00178         /* loop over all block rows */
00179         for (i = 0; i < h_blocks + (h_part?1:0); i++)
00180         {
00181             int wp = i*s->block_width; // vert position in frame
00182             int ws = (i<h_blocks)?s->block_width:h_part; // size of block
00183 
00184             /* get the size of the compressed zlib chunk */
00185             int size = get_bits(&gb, 16);
00186             if (8 * size > get_bits_left(&gb)) {
00187                 avctx->release_buffer(avctx, &s->frame);
00188                 s->frame.data[0] = NULL;
00189                 return -1;
00190             }
00191 
00192             if (size == 0) {
00193                 /* no change, don't do anything */
00194             } else {
00195                 /* decompress block */
00196                 int ret = inflateReset(&(s->zstream));
00197                 if (ret != Z_OK)
00198                 {
00199                     av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
00200                     /* return -1; */
00201                 }
00202                 s->zstream.next_in = buf+(get_bits_count(&gb)/8);
00203                 s->zstream.avail_in = size;
00204                 s->zstream.next_out = s->tmpblock;
00205                 s->zstream.avail_out = s->block_size*3;
00206                 ret = inflate(&(s->zstream), Z_FINISH);
00207                 if (ret == Z_DATA_ERROR)
00208                 {
00209                     av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
00210                     inflateSync(&(s->zstream));
00211                     ret = inflate(&(s->zstream), Z_FINISH);
00212                 }
00213 
00214                 if ((ret != Z_OK) && (ret != Z_STREAM_END))
00215                 {
00216                     av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
00217                     /* return -1; */
00218                 }
00219                 copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
00220                 skip_bits_long(&gb, 8*size);   /* skip the consumed bits */
00221             }
00222         }
00223     }
00224 
00225     *data_size = sizeof(AVFrame);
00226     *(AVFrame*)data = s->frame;
00227 
00228     if ((get_bits_count(&gb)/8) != buf_size)
00229         av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
00230             buf_size, (get_bits_count(&gb)/8));
00231 
00232     /* report that the buffer was completely consumed */
00233     return buf_size;
00234 }
00235 
00236 
00237 static av_cold int flashsv_decode_end(AVCodecContext *avctx)
00238 {
00239     FlashSVContext *s = avctx->priv_data;
00240     inflateEnd(&(s->zstream));
00241     /* release the frame if needed */
00242     if (s->frame.data[0])
00243         avctx->release_buffer(avctx, &s->frame);
00244 
00245     /* free the tmpblock */
00246     if (s->tmpblock != NULL)
00247         av_free(s->tmpblock);
00248 
00249     return 0;
00250 }
00251 
00252 
00253 AVCodec flashsv_decoder = {
00254     "flashsv",
00255     AVMEDIA_TYPE_VIDEO,
00256     CODEC_ID_FLASHSV,
00257     sizeof(FlashSVContext),
00258     flashsv_decode_init,
00259     NULL,
00260     flashsv_decode_end,
00261     flashsv_decode_frame,
00262     CODEC_CAP_DR1,
00263     .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
00264     .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),
00265 };

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