FFmpeg: libavcodec/avs.c Source File

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libavcodec

avs.c

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1 /*

2 * AVS video decoder.

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 */

22 #include "avcodec.h"

23 #include "get_bits.h"

24 #include "internal.h"

27 typedef struct {

28 AVFrame *frame;

29 } AvsContext;

31 typedef enum {

32 AVS_VIDEO = 0x01,

33 AVS_AUDIO = 0x02,

34 AVS_PALETTE = 0x03,

35 AVS_GAME_DATA = 0x04,

36 } AvsBlockType;

38 typedef enum {

39 AVS_I_FRAME = 0x00,

40 AVS_P_FRAME_3X3 = 0x01,

41 AVS_P_FRAME_2X2 = 0x02,

42 AVS_P_FRAME_2X3 = 0x03,

43 } AvsVideoSubType;

46 static int

47 avs_decode_frame(AVCodecContext * avctx,

48 void *data, int *got_frame, AVPacket *avpkt)

49 {

50 const uint8_t *buf = avpkt->data;

51 const uint8_t *buf_end = avpkt->data + avpkt->size;

52 int buf_size = avpkt->size;

53 AvsContext *const avs = avctx->priv_data;

54 AVFrame *picture = data;

55 AVFrame *const p = avs->frame;

56 const uint8_t *table, *vect;

57 uint8_t *out;

58 int i, j, x, y, stride, ret, vect_w = 3, vect_h = 3;

59 AvsVideoSubType sub_type;

60 AvsBlockType type;

61 GetBitContext change_map = {0}; //init to silence warning

63 if ((ret = ff_reget_buffer(avctx, p)) < 0)

64 return ret;

65 p->pict_type = AV_PICTURE_TYPE_P;

66 p->key_frame = 0;

68 out = p->data[0];

69 stride = p->linesize[0];

71 if (buf_end - buf < 4)

72 return AVERROR_INVALIDDATA;

73 sub_type = buf[0];

74 type = buf[1];

75 buf += 4;

77 if (type == AVS_PALETTE) {

78 int first, last;

79 uint32_t *pal = (uint32_t *) p->data[1];

81 first = AV_RL16(buf);

82 last = first + AV_RL16(buf + 2);

83 if (first >= 256 || last > 256 || buf_end - buf < 4 + 4 + 3 * (last - first))

84 return AVERROR_INVALIDDATA;

85 buf += 4;

86 for (i=first; i<last; i++, buf+=3) {

87 pal[i] = (buf[0] << 18) | (buf[1] << 10) | (buf[2] << 2);

88 pal[i] |= 0xFFU << 24 | (pal[i] >> 6) & 0x30303;

89 }

91 sub_type = buf[0];

92 type = buf[1];

93 buf += 4;

94 }

96 if (type != AVS_VIDEO)

97 return AVERROR_INVALIDDATA;

99 switch (sub_type) {

100 case AVS_I_FRAME:

101 p->pict_type = AV_PICTURE_TYPE_I;

102 p->key_frame = 1;

103 case AVS_P_FRAME_3X3:

104 vect_w = 3;

105 vect_h = 3;

106 break;

107

108 case AVS_P_FRAME_2X2:

109 vect_w = 2;

110 vect_h = 2;

111 break;

112

113 case AVS_P_FRAME_2X3:

114 vect_w = 2;

115 vect_h = 3;

116 break;

117

118 default:

119 return AVERROR_INVALIDDATA;

120 }

121

122 if (buf_end - buf < 256 * vect_w * vect_h)

123 return AVERROR_INVALIDDATA;

124 table = buf + (256 * vect_w * vect_h);

125 if (sub_type != AVS_I_FRAME) {

126 int map_size = ((318 / vect_w + 7) / 8) * (198 / vect_h);

127 if (buf_end - table < map_size)

128 return AVERROR_INVALIDDATA;

129 init_get_bits(&change_map, table, map_size * 8);

130 table += map_size;

131 }

132

133 for (y=0; y<198; y+=vect_h) {

134 for (x=0; x<318; x+=vect_w) {

135 if (sub_type == AVS_I_FRAME || get_bits1(&change_map)) {

136 if (buf_end - table < 1)

137 return AVERROR_INVALIDDATA;

138 vect = &buf[*table++ * (vect_w * vect_h)];

139 for (j=0; j<vect_w; j++) {

140 out[(y + 0) * stride + x + j] = vect[(0 * vect_w) + j];

141 out[(y + 1) * stride + x + j] = vect[(1 * vect_w) + j];

142 if (vect_h == 3)

143 out[(y + 2) * stride + x + j] =

144 vect[(2 * vect_w) + j];

145 }

146 }

147 }

148 if (sub_type != AVS_I_FRAME)

149 align_get_bits(&change_map);

150 }

151

152 if ((ret = av_frame_ref(picture, p)) < 0)

153 return ret;

154 *got_frame = 1;

155

156 return buf_size;

157 }

158

159 static av_cold int avs_decode_init(AVCodecContext * avctx)

160 {

161 AvsContext *s = avctx->priv_data;

162

163 s->frame = av_frame_alloc();

164 if (!s->frame)

165 return AVERROR(ENOMEM);

166

167 avctx->pix_fmt = AV_PIX_FMT_PAL8;

168 avcodec_set_dimensions(avctx, 318, 198);

169

170 return 0;

171 }

172

173 static av_cold int avs_decode_end(AVCodecContext *avctx)

174 {

175 AvsContext *s = avctx->priv_data;

176 av_frame_free(&s->frame);

177 return 0;

178 }

179

180

181 AVCodec ff_avs_decoder = {

182 .name = "avs",

183 .long_name = NULL_IF_CONFIG_SMALL("AVS (Audio Video Standard) video"),

184 .type = AVMEDIA_TYPE_VIDEO,

185 .id = AV_CODEC_ID_AVS,

186 .priv_data_size = sizeof(AvsContext),

187 .init = avs_decode_init,

188 .decode = avs_decode_frame,

189 .close = avs_decode_end,

190 .capabilities = CODEC_CAP_DR1,

191 };

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