FFmpeg: libavcodec/msvideo1.c Source File

00001 /*
00002  * Microsoft Video-1 Decoder
00003  * Copyright (C) 2003 the ffmpeg project
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 <stdio.h>
00031 #include <stdlib.h>
00032 #include <string.h>
00033 
00034 #include "libavutil/intreadwrite.h"
00035 #include "avcodec.h"
00036 
00037 #define PALETTE_COUNT 256
00038 #define CHECK_STREAM_PTR(n) \
00039   if ((stream_ptr + n) > s->size ) { \
00040     av_log(s->avctx, AV_LOG_ERROR, " MS Video-1 warning: stream_ptr out of bounds (%d >= %d)\n", \
00041       stream_ptr + n, s->size); \
00042     return; \
00043   }
00044 
00045 typedef struct Msvideo1Context {
00046 
00047     AVCodecContext *avctx;
00048     AVFrame frame;
00049 
00050     const unsigned char *buf;
00051     int size;
00052 
00053     int mode_8bit;  /* if it's not 8-bit, it's 16-bit */
00054 
00055     uint32_t pal[256];
00056 } Msvideo1Context;
00057 
00058 static av_cold int msvideo1_decode_init(AVCodecContext *avctx)
00059 {
00060     Msvideo1Context *s = avctx->priv_data;
00061 
00062     s->avctx = avctx;
00063 
00064     /* figure out the colorspace based on the presence of a palette */
00065     if (s->avctx->bits_per_coded_sample == 8) {
00066         s->mode_8bit = 1;
00067         avctx->pix_fmt = PIX_FMT_PAL8;
00068     } else {
00069         s->mode_8bit = 0;
00070         avctx->pix_fmt = PIX_FMT_RGB555;
00071     }
00072 
00073     avcodec_get_frame_defaults(&s->frame);
00074     s->frame.data[0] = NULL;
00075 
00076     return 0;
00077 }
00078 
00079 static void msvideo1_decode_8bit(Msvideo1Context *s)
00080 {
00081     int block_ptr, pixel_ptr;
00082     int total_blocks;
00083     int pixel_x, pixel_y;  /* pixel width and height iterators */
00084     int block_x, block_y;  /* block width and height iterators */
00085     int blocks_wide, blocks_high;  /* width and height in 4x4 blocks */
00086     int block_inc;
00087     int row_dec;
00088 
00089     /* decoding parameters */
00090     int stream_ptr;
00091     unsigned char byte_a, byte_b;
00092     unsigned short flags;
00093     int skip_blocks;
00094     unsigned char colors[8];
00095     unsigned char *pixels = s->frame.data[0];
00096     int stride = s->frame.linesize[0];
00097 
00098     stream_ptr = 0;
00099     skip_blocks = 0;
00100     blocks_wide = s->avctx->width / 4;
00101     blocks_high = s->avctx->height / 4;
00102     total_blocks = blocks_wide * blocks_high;
00103     block_inc = 4;
00104     row_dec = stride + 4;
00105 
00106     for (block_y = blocks_high; block_y > 0; block_y--) {
00107         block_ptr = ((block_y * 4) - 1) * stride;
00108         for (block_x = blocks_wide; block_x > 0; block_x--) {
00109             /* check if this block should be skipped */
00110             if (skip_blocks) {
00111                 block_ptr += block_inc;
00112                 skip_blocks--;
00113                 total_blocks--;
00114                 continue;
00115             }
00116 
00117             pixel_ptr = block_ptr;
00118 
00119             /* get the next two bytes in the encoded data stream */
00120             CHECK_STREAM_PTR(2);
00121             byte_a = s->buf[stream_ptr++];
00122             byte_b = s->buf[stream_ptr++];
00123 
00124             /* check if the decode is finished */
00125             if ((byte_a == 0) && (byte_b == 0) && (total_blocks == 0))
00126                 return;
00127             else if ((byte_b & 0xFC) == 0x84) {
00128                 /* skip code, but don't count the current block */
00129                 skip_blocks = ((byte_b - 0x84) << 8) + byte_a - 1;
00130             } else if (byte_b < 0x80) {
00131                 /* 2-color encoding */
00132                 flags = (byte_b << 8) | byte_a;
00133 
00134                 CHECK_STREAM_PTR(2);
00135                 colors[0] = s->buf[stream_ptr++];
00136                 colors[1] = s->buf[stream_ptr++];
00137 
00138                 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
00139                     for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
00140                         pixels[pixel_ptr++] = colors[(flags & 0x1) ^ 1];
00141                     pixel_ptr -= row_dec;
00142                 }
00143             } else if (byte_b >= 0x90) {
00144                 /* 8-color encoding */
00145                 flags = (byte_b << 8) | byte_a;
00146 
00147                 CHECK_STREAM_PTR(8);
00148                 memcpy(colors, &s->buf[stream_ptr], 8);
00149                 stream_ptr += 8;
00150 
00151                 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
00152                     for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
00153                         pixels[pixel_ptr++] =
00154                             colors[((pixel_y & 0x2) << 1) +
00155                                 (pixel_x & 0x2) + ((flags & 0x1) ^ 1)];
00156                     pixel_ptr -= row_dec;
00157                 }
00158             } else {
00159                 /* 1-color encoding */
00160                 colors[0] = byte_a;
00161 
00162                 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
00163                     for (pixel_x = 0; pixel_x < 4; pixel_x++)
00164                         pixels[pixel_ptr++] = colors[0];
00165                     pixel_ptr -= row_dec;
00166                 }
00167             }
00168 
00169             block_ptr += block_inc;
00170             total_blocks--;
00171         }
00172     }
00173 
00174     /* make the palette available on the way out */
00175     if (s->avctx->pix_fmt == PIX_FMT_PAL8)
00176         memcpy(s->frame.data[1], s->pal, AVPALETTE_SIZE);
00177 }
00178 
00179 static void msvideo1_decode_16bit(Msvideo1Context *s)
00180 {
00181     int block_ptr, pixel_ptr;
00182     int total_blocks;
00183     int pixel_x, pixel_y;  /* pixel width and height iterators */
00184     int block_x, block_y;  /* block width and height iterators */
00185     int blocks_wide, blocks_high;  /* width and height in 4x4 blocks */
00186     int block_inc;
00187     int row_dec;
00188 
00189     /* decoding parameters */
00190     int stream_ptr;
00191     unsigned char byte_a, byte_b;
00192     unsigned short flags;
00193     int skip_blocks;
00194     unsigned short colors[8];
00195     unsigned short *pixels = (unsigned short *)s->frame.data[0];
00196     int stride = s->frame.linesize[0] / 2;
00197 
00198     stream_ptr = 0;
00199     skip_blocks = 0;
00200     blocks_wide = s->avctx->width / 4;
00201     blocks_high = s->avctx->height / 4;
00202     total_blocks = blocks_wide * blocks_high;
00203     block_inc = 4;
00204     row_dec = stride + 4;
00205 
00206     for (block_y = blocks_high; block_y > 0; block_y--) {
00207         block_ptr = ((block_y * 4) - 1) * stride;
00208         for (block_x = blocks_wide; block_x > 0; block_x--) {
00209             /* check if this block should be skipped */
00210             if (skip_blocks) {
00211                 block_ptr += block_inc;
00212                 skip_blocks--;
00213                 total_blocks--;
00214                 continue;
00215             }
00216 
00217             pixel_ptr = block_ptr;
00218 
00219             /* get the next two bytes in the encoded data stream */
00220             CHECK_STREAM_PTR(2);
00221             byte_a = s->buf[stream_ptr++];
00222             byte_b = s->buf[stream_ptr++];
00223 
00224             /* check if the decode is finished */
00225             if ((byte_a == 0) && (byte_b == 0) && (total_blocks == 0)) {
00226                 return;
00227             } else if ((byte_b & 0xFC) == 0x84) {
00228                 /* skip code, but don't count the current block */
00229                 skip_blocks = ((byte_b - 0x84) << 8) + byte_a - 1;
00230             } else if (byte_b < 0x80) {
00231                 /* 2- or 8-color encoding modes */
00232                 flags = (byte_b << 8) | byte_a;
00233 
00234                 CHECK_STREAM_PTR(4);
00235                 colors[0] = AV_RL16(&s->buf[stream_ptr]);
00236                 stream_ptr += 2;
00237                 colors[1] = AV_RL16(&s->buf[stream_ptr]);
00238                 stream_ptr += 2;
00239 
00240                 if (colors[0] & 0x8000) {
00241                     /* 8-color encoding */
00242                     CHECK_STREAM_PTR(12);
00243                     colors[2] = AV_RL16(&s->buf[stream_ptr]);
00244                     stream_ptr += 2;
00245                     colors[3] = AV_RL16(&s->buf[stream_ptr]);
00246                     stream_ptr += 2;
00247                     colors[4] = AV_RL16(&s->buf[stream_ptr]);
00248                     stream_ptr += 2;
00249                     colors[5] = AV_RL16(&s->buf[stream_ptr]);
00250                     stream_ptr += 2;
00251                     colors[6] = AV_RL16(&s->buf[stream_ptr]);
00252                     stream_ptr += 2;
00253                     colors[7] = AV_RL16(&s->buf[stream_ptr]);
00254                     stream_ptr += 2;
00255 
00256                     for (pixel_y = 0; pixel_y < 4; pixel_y++) {
00257                         for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
00258                             pixels[pixel_ptr++] =
00259                                 colors[((pixel_y & 0x2) << 1) +
00260                                     (pixel_x & 0x2) + ((flags & 0x1) ^ 1)];
00261                         pixel_ptr -= row_dec;
00262                     }
00263                 } else {
00264                     /* 2-color encoding */
00265                     for (pixel_y = 0; pixel_y < 4; pixel_y++) {
00266                         for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
00267                             pixels[pixel_ptr++] = colors[(flags & 0x1) ^ 1];
00268                         pixel_ptr -= row_dec;
00269                     }
00270                 }
00271             } else {
00272                 /* otherwise, it's a 1-color block */
00273                 colors[0] = (byte_b << 8) | byte_a;
00274 
00275                 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
00276                     for (pixel_x = 0; pixel_x < 4; pixel_x++)
00277                         pixels[pixel_ptr++] = colors[0];
00278                     pixel_ptr -= row_dec;
00279                 }
00280             }
00281 
00282             block_ptr += block_inc;
00283             total_blocks--;
00284         }
00285     }
00286 }
00287 
00288 static int msvideo1_decode_frame(AVCodecContext *avctx,
00289                                 void *data, int *data_size,
00290                                 AVPacket *avpkt)
00291 {
00292     const uint8_t *buf = avpkt->data;
00293     int buf_size = avpkt->size;
00294     Msvideo1Context *s = avctx->priv_data;
00295 
00296     s->buf = buf;
00297     s->size = buf_size;
00298 
00299     s->frame.reference = 3;
00300     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
00301     if (avctx->reget_buffer(avctx, &s->frame)) {
00302         av_log(s->avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
00303         return -1;
00304     }
00305 
00306     if (s->mode_8bit) {
00307         const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL);
00308 
00309         if (pal) {
00310             memcpy(s->pal, pal, AVPALETTE_SIZE);
00311             s->frame.palette_has_changed = 1;
00312         }
00313     }
00314 
00315     if (s->mode_8bit)
00316         msvideo1_decode_8bit(s);
00317     else
00318         msvideo1_decode_16bit(s);
00319 
00320     *data_size = sizeof(AVFrame);
00321     *(AVFrame*)data = s->frame;
00322 
00323     /* report that the buffer was completely consumed */
00324     return buf_size;
00325 }
00326 
00327 static av_cold int msvideo1_decode_end(AVCodecContext *avctx)
00328 {
00329     Msvideo1Context *s = avctx->priv_data;
00330 
00331     if (s->frame.data[0])
00332         avctx->release_buffer(avctx, &s->frame);
00333 
00334     return 0;
00335 }
00336 
00337 AVCodec ff_msvideo1_decoder = {
00338     .name           = "msvideo1",
00339     .type           = AVMEDIA_TYPE_VIDEO,
00340     .id             = CODEC_ID_MSVIDEO1,
00341     .priv_data_size = sizeof(Msvideo1Context),
00342     .init           = msvideo1_decode_init,
00343     .close          = msvideo1_decode_end,
00344     .decode         = msvideo1_decode_frame,
00345     .capabilities   = CODEC_CAP_DR1,
00346     .long_name= NULL_IF_CONFIG_SMALL("Microsoft Video 1"),
00347 };