libavcodec/wnv1.c

   1 /*
   2  * Winnov WNV1 codec
   3  * Copyright (c) 2005 Konstantin Shishkov
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * Winnov WNV1 codec.
  25  */
  26
  27 #include "libavutil/thread.h"
  28
  29 #define BITSTREAM_READER_LE
  30 #include "avcodec.h"
  31 #include "codec_internal.h"
  32 #include "decode.h"
  33 #include "get_bits.h"
  34
  35 static const uint8_t code_tab[16][2] = {
  36     {  7, 1 }, {  8, 3 }, {  6, 3 }, { 9, 4 }, {  5, 4 }, { 10, 5 }, {  4, 5 },
  37     { 11, 6 }, {  3, 6 }, { 12, 7 }, { 2, 7 }, { 13, 8 }, {  1, 8 }, { 14, 9 },
  38     {  0, 9 }, { 15, 8 }
  39 };
  40
  41 #define CODE_VLC_BITS 9
  42 static VLCElem code_vlc[1 << CODE_VLC_BITS];
  43
  44 /* returns modified base_value */
  45 static inline int wnv1_get_code(GetBitContext *gb, int shift, int base_value)
  46 {
  47     int v = get_vlc2(gb, code_vlc, CODE_VLC_BITS, 1);
  48
  49     if (v == 8)
  50         return get_bits(gb, 8 - shift) << shift;
  51     else
  52         return base_value + v * (1 << shift);
  53 }
  54
  55 static int decode_frame(AVCodecContext *avctx, AVFrame *p,
  56                         int *got_frame, AVPacket *avpkt)
  57 {
  58     const uint8_t *buf    = avpkt->data;
  59     int buf_size          = avpkt->size;
  60     GetBitContext gb;
  61     unsigned char *Y,*U,*V;
  62     int i, j, ret, shift;
  63     int prev_y = 0, prev_u = 0, prev_v = 0;
  64
  65     if (buf_size < 8 + avctx->height * (avctx->width/2)/8) {
  66         av_log(avctx, AV_LOG_ERROR, "Packet size %d is too small\n", buf_size);
  67         return AVERROR_INVALIDDATA;
  68     }
  69
  70     if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
  71         return ret;
  72
  73     if ((ret = init_get_bits8(&gb, buf + 8, buf_size - 8)) < 0)
  74         return ret;
  75
  76     if (buf[2] >> 4 == 6)
  77         shift = 2;
  78     else {
  79         shift = 8 - (buf[2] >> 4);
  80         if (shift > 4) {
  81             avpriv_request_sample(avctx,
  82                                   "Unknown WNV1 frame header value %i",
  83                                   buf[2] >> 4);
  84             shift = 4;
  85         }
  86         if (shift < 1) {
  87             avpriv_request_sample(avctx,
  88                                   "Unknown WNV1 frame header value %i",
  89                                   buf[2] >> 4);
  90             shift = 1;
  91         }
  92     }
  93
  94     Y = p->data[0];
  95     U = p->data[1];
  96     V = p->data[2];
  97     for (j = 0; j < avctx->height; j++) {
  98         for (i = 0; i < avctx->width / 2; i++) {
  99             Y[i * 2] = wnv1_get_code(&gb, shift, prev_y);
 100             prev_u = U[i] = wnv1_get_code(&gb, shift, prev_u);
 101             prev_y = Y[(i * 2) + 1] = wnv1_get_code(&gb, shift, Y[i * 2]);
 102             prev_v = V[i] = wnv1_get_code(&gb, shift, prev_v);
 103         }
 104         Y += p->linesize[0];
 105         U += p->linesize[1];
 106         V += p->linesize[2];
 107     }
 108
 109
 110     *got_frame      = 1;
 111
 112     return buf_size;
 113 }
 114
 115 static av_cold void wnv1_init_static(void)
 116 {
 117     VLC_INIT_STATIC_TABLE_FROM_LENGTHS(code_vlc, CODE_VLC_BITS, 16,
 118                                        &code_tab[0][1], 2,
 119                                        &code_tab[0][0], 2, 1,
 120                                        -7, VLC_INIT_OUTPUT_LE);
 121 }
 122
 123 static av_cold int decode_init(AVCodecContext *avctx)
 124 {
 125     static AVOnce init_static_once = AV_ONCE_INIT;
 126
 127     if (avctx->width <= 1)
 128         return AVERROR_INVALIDDATA;
 129
 130     avctx->pix_fmt = AV_PIX_FMT_YUV422P;
 131
 132     ff_thread_once(&init_static_once, wnv1_init_static);
 133
 134     return 0;
 135 }
 136
 137 const FFCodec ff_wnv1_decoder = {
 138     .p.name         = "wnv1",
 139     CODEC_LONG_NAME("Winnov WNV1"),
 140     .p.type         = AVMEDIA_TYPE_VIDEO,
 141     .p.id           = AV_CODEC_ID_WNV1,
 142     .init           = decode_init,
 143     FF_CODEC_DECODE_CB(decode_frame),
 144     .p.capabilities = AV_CODEC_CAP_DR1,
 145 };