FFmpeg: libavcodec/kgv1dec.c Source File

FFmpeg

[フレーム]

libavcodec

kgv1dec.c

Go to the documentation of this file.

1 /*

2 * Kega Game Video (KGV1) 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 /**

23 * @file

24 * Kega Game Video decoder

25 */

27 #include "libavutil/common.h"

28 #include "libavutil/intreadwrite.h"

29 #include "libavutil/imgutils.h"

30 #include "avcodec.h"

31 #include "internal.h"

33 typedef struct KgvContext {

34 uint16_t *frame_buffer;

35 uint16_t *last_frame_buffer;

36 } KgvContext;

38 static void decode_flush(AVCodecContext *avctx)

39 {

40 KgvContext * const c = avctx->priv_data;

42 av_freep(&c->frame_buffer);

43 av_freep(&c->last_frame_buffer);

44 }

46 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

47 AVPacket *avpkt)

48 {

49 AVFrame *frame = data;

50 const uint8_t *buf = avpkt->data;

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

52 KgvContext * const c = avctx->priv_data;

53 int offsets[8];

54 uint8_t *out, *prev;

55 int outcnt = 0, maxcnt;

56 int w, h, i, res;

58 if (avpkt->size < 2)

59 return AVERROR_INVALIDDATA;

61 w = (buf[0] + 1) * 8;

62 h = (buf[1] + 1) * 8;

63 buf += 2;

65 if (w != avctx->width || h != avctx->height) {

66 av_freep(&c->frame_buffer);

67 av_freep(&c->last_frame_buffer);

68 if ((res = ff_set_dimensions(avctx, w, h)) < 0)

69 return res;

70 }

72 if (!c->frame_buffer) {

73 c->frame_buffer = av_mallocz(avctx->width * avctx->height * 2);

74 c->last_frame_buffer = av_mallocz(avctx->width * avctx->height * 2);

75 if (!c->frame_buffer || !c->last_frame_buffer) {

76 decode_flush(avctx);

77 return AVERROR(ENOMEM);

78 }

79 }

81 maxcnt = w * h;

83 if ((res = ff_get_buffer(avctx, frame, 0)) < 0)

84 return res;

85 out = (uint8_t*)c->frame_buffer;

86 prev = (uint8_t*)c->last_frame_buffer;

88 for (i = 0; i < 8; i++)

89 offsets[i] = -1;

91 while (outcnt < maxcnt && buf_end - 2 >= buf) {

92 int code = AV_RL16(buf);

93 buf += 2;

95 if (!(code & 0x8000)) {

96 AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly

97 outcnt++;

98 } else {

99 int count;

100

101 if ((code & 0x6000) == 0x6000) {

102 // copy from previous frame

103 int oidx = (code >> 10) & 7;

104 int start;

105

106 count = (code & 0x3FF) + 3;

107

108 if (offsets[oidx] < 0) {

109 if (buf_end - 3 < buf)

110 break;

111 offsets[oidx] = AV_RL24(buf);

112 buf += 3;

113 }

114

115 start = (outcnt + offsets[oidx]) % maxcnt;

116

117 if (maxcnt - start < count || maxcnt - outcnt < count)

118 break;

119

120 if (!prev) {

121 av_log(avctx, AV_LOG_ERROR,

122 "Frame reference does not exist\n");

123 break;

124 }

125

126 memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count);

127 } else {

128 // copy from earlier in this frame

129 int offset = (code & 0x1FFF) + 1;

130

131 if (!(code & 0x6000)) {

132 count = 2;

133 } else if ((code & 0x6000) == 0x2000) {

134 count = 3;

135 } else {

136 if (buf_end - 1 < buf)

137 break;

138 count = 4 + *buf++;

139 }

140

141 if (outcnt < offset || maxcnt - outcnt < count)

142 break;

143

144 av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count);

145 }

146 outcnt += count;

147 }

148 }

149

150 if (outcnt - maxcnt)

151 av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);

152

153 av_image_copy_plane(frame->data[0], frame->linesize[0],

154 (const uint8_t*)c->frame_buffer, avctx->width * 2,

155 avctx->width * 2, avctx->height);

156 FFSWAP(uint16_t *, c->frame_buffer, c->last_frame_buffer);

157

158 *got_frame = 1;

159

160 return avpkt->size;

161 }

162

163 static av_cold int decode_init(AVCodecContext *avctx)

164 {

165 avctx->pix_fmt = AV_PIX_FMT_RGB555;

166

167 return 0;

168 }

169

170 static av_cold int decode_end(AVCodecContext *avctx)

171 {

172 decode_flush(avctx);

173 return 0;

174 }

175

176 AVCodec ff_kgv1_decoder = {

177 .name = "kgv1",

178 .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),

179 .type = AVMEDIA_TYPE_VIDEO,

180 .id = AV_CODEC_ID_KGV1,

181 .priv_data_size = sizeof(KgvContext),

182 .init = decode_init,

183 .close = decode_end,

184 .decode = decode_frame,

185 .flush = decode_flush,

186 .capabilities = CODEC_CAP_DR1,

187 };

Generated on Sun Mar 8 2015 02:34:54 for FFmpeg by doxygen 1.8.2