FFmpeg: libavcodec/gif.c Source File

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libavcodec

gif.c

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1 /*

5 *

6 * first version by Francois Revol <revol@free.fr>

7 *

8 * This file is part of FFmpeg.

9 *

10 * FFmpeg is free software; you can redistribute it and/or

11 * modify it under the terms of the GNU Lesser General Public

12 * License as published by the Free Software Foundation; either

13 * version 2.1 of the License, or (at your option) any later version.

14 *

15 * FFmpeg is distributed in the hope that it will be useful,

16 * but WITHOUT ANY WARRANTY; without even the implied warranty of

17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

18 * Lesser General Public License for more details.

19 *

20 * You should have received a copy of the GNU Lesser General Public

21 * License along with FFmpeg; if not, write to the Free Software

22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

23 */

25 /**

26 * @file

27 * GIF encoder

28 * @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt

29 */

31 #include "libavutil/opt.h"

32 #include "libavutil/imgutils.h"

33 #include "avcodec.h"

34 #include "bytestream.h"

35 #include "internal.h"

36 #include "lzw.h"

37 #include "gif.h"

39 #define BITSTREAM_WRITER_LE

40 #include "put_bits.h"

42 typedef struct {

43 const AVClass *class;

44 LZWState *lzw;

45 uint8_t *buf;

46 AVFrame *last_frame;

47 int flags;

48 uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8

49 uint8_t *tmpl; ///< temporary line buffer

50 } GIFContext;

52 enum {

53 GF_OFFSETTING = 1<<0,

54 GF_TRANSDIFF = 1<<1,

55 };

57 static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)

58 {

59 int histogram[AVPALETTE_COUNT] = {0};

60 int x, y, i;

62 for (y = 0; y < h; y++) {

63 for (x = 0; x < w; x++)

64 histogram[buf[x]]++;

65 buf += linesize;

66 }

67 for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)

68 if (!histogram[i])

69 return i;

70 return -1;

71 }

73 static int gif_image_write_image(AVCodecContext *avctx,

74 uint8_t **bytestream, uint8_t *end,

75 const uint32_t *palette,

76 const uint8_t *buf, const int linesize,

77 AVPacket *pkt)

78 {

79 GIFContext *s = avctx->priv_data;

80 int len = 0, height = avctx->height, width = avctx->width, x, y;

81 int x_start = 0, y_start = 0, trans = -1;

82 const uint8_t *ptr;

84 /* Crop image */

85 // TODO support with palette change

86 if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {

87 const uint8_t *ref = s->last_frame->data[0];

88 const int ref_linesize = s->last_frame->linesize[0];

89 int x_end = avctx->width - 1,

90 y_end = avctx->height - 1;

92 /* skip common lines */

93 while (y_start < y_end) {

94 if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))

95 break;

96 y_start++;

97 }

98 while (y_end > y_start) {

99 if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))

100 break;

101 y_end--;

102 }

103 height = y_end + 1 - y_start;

104

105 /* skip common columns */

106 while (x_start < x_end) {

107 int same_column = 1;

108 for (y = y_start; y < y_end; y++) {

109 if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {

110 same_column = 0;

111 break;

112 }

113 }

114 if (!same_column)

115 break;

116 x_start++;

117 }

118 while (x_end > x_start) {

119 int same_column = 1;

120 for (y = y_start; y < y_end; y++) {

121 if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {

122 same_column = 0;

123 break;

124 }

125 }

126 if (!same_column)

127 break;

128 x_end--;

129 }

130 width = x_end + 1 - x_start;

131

132 av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",

133 width, height, x_start, y_start, avctx->width, avctx->height);

134 }

135

136 /* image block */

137 bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);

138 bytestream_put_le16(bytestream, x_start);

139 bytestream_put_le16(bytestream, y_start);

140 bytestream_put_le16(bytestream, width);

141 bytestream_put_le16(bytestream, height);

142

143 if (!palette) {

144 bytestream_put_byte(bytestream, 0x00); /* flags */

145 } else {

146 unsigned i;

147 bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */

148 for (i = 0; i < AVPALETTE_COUNT; i++) {

149 const uint32_t v = palette[i];

150 bytestream_put_be24(bytestream, v);

151 }

152 }

153

154 /* TODO: support with palette change (pal8) */

155 if ((s->flags & GF_TRANSDIFF) && s->last_frame && !palette) {

156 trans = pick_palette_entry(buf + y_start*linesize + x_start,

157 linesize, width, height);

158 if (trans < 0) { // TODO, patch welcome

159 av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");

160 } else {

161 uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);

162 if (!pal_exdata)

163 return AVERROR(ENOMEM);

164 memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);

165 pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;

166 }

167 }

168

169 bytestream_put_byte(bytestream, 0x08);

170

171 ff_lzw_encode_init(s->lzw, s->buf, width * height,

172 12, FF_LZW_GIF, put_bits);

173

174 ptr = buf + y_start*linesize + x_start;

175 if (trans >= 0) {

176 const int ref_linesize = s->last_frame->linesize[0];

177 const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;

178

179 for (y = 0; y < height; y++) {

180 memcpy(s->tmpl, ptr, width);

181 for (x = 0; x < width; x++)

182 if (ref[x] == ptr[x])

183 s->tmpl[x] = trans;

184 len += ff_lzw_encode(s->lzw, s->tmpl, width);

185 ptr += linesize;

186 ref += ref_linesize;

187 }

188 } else {

189 for (y = 0; y < height; y++) {

190 len += ff_lzw_encode(s->lzw, ptr, width);

191 ptr += linesize;

192 }

193 }

194 len += ff_lzw_encode_flush(s->lzw, flush_put_bits);

195

196 ptr = s->buf;

197 while (len > 0) {

198 int size = FFMIN(255, len);

199 bytestream_put_byte(bytestream, size);

200 if (end - *bytestream < size)

201 return -1;

202 bytestream_put_buffer(bytestream, ptr, size);

203 ptr += size;

204 len -= size;

205 }

206 bytestream_put_byte(bytestream, 0x00); /* end of image block */

207 return 0;

208 }

209

210 static av_cold int gif_encode_init(AVCodecContext *avctx)

211 {

212 GIFContext *s = avctx->priv_data;

213

214 if (avctx->width > 65535 || avctx->height > 65535) {

215 av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");

216 return AVERROR(EINVAL);

217 }

218

219 s->lzw = av_mallocz(ff_lzw_encode_state_size);

220 s->buf = av_malloc(avctx->width*avctx->height*2);

221 s->tmpl = av_malloc(avctx->width);

222 if (!s->tmpl || !s->buf || !s->lzw)

223 return AVERROR(ENOMEM);

224

225 if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)

226 av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);

227

228 return 0;

229 }

230

231 static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,

232 const AVFrame *pict, int *got_packet)

233 {

234 GIFContext *s = avctx->priv_data;

235 AVFrame *const p = (AVFrame *)pict;

236 uint8_t *outbuf_ptr, *end;

237 const uint32_t *palette = NULL;

238 int ret;

239

240 if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + FF_MIN_BUFFER_SIZE)) < 0)

241 return ret;

242 outbuf_ptr = pkt->data;

243 end = pkt->data + pkt->size;

244

245 p->pict_type = AV_PICTURE_TYPE_I;

246 p->key_frame = 1;

247

248 if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {

249 uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);

250 if (!pal_exdata)

251 return AVERROR(ENOMEM);

252 memcpy(pal_exdata, p->data[1], AVPALETTE_SIZE);

253 palette = (uint32_t*)p->data[1];

254 }

255

256 gif_image_write_image(avctx, &outbuf_ptr, end, palette,

257 pict->data[0], pict->linesize[0], pkt);

258 if (!s->last_frame) {

259 s->last_frame = av_frame_alloc();

260 if (!s->last_frame)

261 return AVERROR(ENOMEM);

262 }

263 av_frame_unref(s->last_frame);

264 ret = av_frame_ref(s->last_frame, (AVFrame*)pict);

265 if (ret < 0)

266 return ret;

267

268 pkt->size = outbuf_ptr - pkt->data;

269 pkt->flags |= AV_PKT_FLAG_KEY;

270 *got_packet = 1;

271

272 return 0;

273 }

274

275 static int gif_encode_close(AVCodecContext *avctx)

276 {

277 GIFContext *s = avctx->priv_data;

278

279 av_freep(&s->lzw);

280 av_freep(&s->buf);

281 av_frame_free(&s->last_frame);

282 av_freep(&s->tmpl);

283 return 0;

284 }

285

286 #define OFFSET(x) offsetof(GIFContext, x)

287 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM

288 static const AVOption gif_options[] = {

289 { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },

290 { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },

291 { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },

292 { NULL }

293 };

294

295 static const AVClass gif_class = {

296 .class_name = "GIF encoder",

297 .item_name = av_default_item_name,

298 .option = gif_options,

299 .version = LIBAVUTIL_VERSION_INT,

300 };

301

302 AVCodec ff_gif_encoder = {

303 .name = "gif",

304 .type = AVMEDIA_TYPE_VIDEO,

305 .id = AV_CODEC_ID_GIF,

306 .priv_data_size = sizeof(GIFContext),

307 .init = gif_encode_init,

308 .encode2 = gif_encode_frame,

309 .close = gif_encode_close,

310 .pix_fmts = (const enum AVPixelFormat[]){

311 AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,

312 AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE

313 },

314 .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),

315 .priv_class = &gif_class,

316 };

Generated on Wed Jul 10 2013 23:47:58 for FFmpeg by doxygen 1.8.2