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"

26 typedef struct AvsContext {

27 AVFrame *frame;

28 } AvsContext;

30 typedef enum {

31 AVS_VIDEO = 0x01,

32 AVS_AUDIO = 0x02,

33 AVS_PALETTE = 0x03,

34 AVS_GAME_DATA = 0x04,

35 } AvsBlockType;

37 typedef enum {

38 AVS_I_FRAME = 0x00,

39 AVS_P_FRAME_3X3 = 0x01,

40 AVS_P_FRAME_2X2 = 0x02,

41 AVS_P_FRAME_2X3 = 0x03,

42 } AvsVideoSubType;

45 static int

46 avs_decode_frame(AVCodecContext * avctx,

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

48 {

49 const uint8_t *buf = avpkt->data;

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

51 int buf_size = avpkt->size;

52 AvsContext *const avs = avctx->priv_data;

53 AVFrame *picture = data;

54 AVFrame *const p = avs->frame;

55 const uint8_t *table, *vect;

56 uint8_t *out;

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

58 AvsVideoSubType sub_type;

59 AvsBlockType type;

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

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

63 return ret;

64 p->pict_type = AV_PICTURE_TYPE_P;

65 p->key_frame = 0;

67 out = p->data[0];

68 stride = p->linesize[0];

70 if (buf_end - buf < 4)

71 return AVERROR_INVALIDDATA;

72 sub_type = buf[0];

73 type = buf[1];

74 buf += 4;

76 if (type == AVS_PALETTE) {

77 int first, last;

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

80 first = AV_RL16(buf);

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

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

83 return AVERROR_INVALIDDATA;

84 buf += 4;

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

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

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

88 }

90 sub_type = buf[0];

91 type = buf[1];

92 buf += 4;

93 }

95 if (type != AVS_VIDEO)

96 return AVERROR_INVALIDDATA;

98 switch (sub_type) {

99 case AVS_I_FRAME:

100 p->pict_type = AV_PICTURE_TYPE_I;

101 p->key_frame = 1;

102 case AVS_P_FRAME_3X3:

103 vect_w = 3;

104 vect_h = 3;

105 break;

106

107 case AVS_P_FRAME_2X2:

108 vect_w = 2;

109 vect_h = 2;

110 break;

111

112 case AVS_P_FRAME_2X3:

113 vect_w = 2;

114 vect_h = 3;

115 break;

116

117 default:

118 return AVERROR_INVALIDDATA;

119 }

120

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

122 return AVERROR_INVALIDDATA;

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

124 if (sub_type != AVS_I_FRAME) {

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

126 if (buf_end - table < map_size)

127 return AVERROR_INVALIDDATA;

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

129 table += map_size;

130 }

131

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

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

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

135 if (buf_end - table < 1)

136 return AVERROR_INVALIDDATA;

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

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

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

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

141 if (vect_h == 3)

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

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

144 }

145 }

146 }

147 if (sub_type != AVS_I_FRAME)

148 align_get_bits(&change_map);

149 }

150

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

152 return ret;

153 *got_frame = 1;

154

155 return buf_size;

156 }

157

158 static av_cold int avs_decode_init(AVCodecContext * avctx)

159 {

160 AvsContext *s = avctx->priv_data;

161

162 s->frame = av_frame_alloc();

163 if (!s->frame)

164 return AVERROR(ENOMEM);

165

166 avctx->pix_fmt = AV_PIX_FMT_PAL8;

167

168 return ff_set_dimensions(avctx, 318, 198);

169 }

170

171 static av_cold int avs_decode_end(AVCodecContext *avctx)

172 {

173 AvsContext *s = avctx->priv_data;

174 av_frame_free(&s->frame);

175 return 0;

176 }

177

178

179 AVCodec ff_avs_decoder = {

180 .name = "avs",

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

182 .type = AVMEDIA_TYPE_VIDEO,

183 .id = AV_CODEC_ID_AVS,

184 .priv_data_size = sizeof(AvsContext),

185 .init = avs_decode_init,

186 .decode = avs_decode_frame,

187 .close = avs_decode_end,

188 .capabilities = CODEC_CAP_DR1,

189 };

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