FFmpeg: libavcodec/flashsvenc.c Source File

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libavcodec

flashsvenc.c

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1 /*

2 * Flash Screen Video encoder

5 *

6 * This file is part of FFmpeg.

7 *

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

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

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

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

12 *

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

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

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

16 * Lesser General Public License for more details.

17 *

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

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

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

21 */

23 /* Encoding development sponsored by http://fh-campuswien.ac.at */

25 /**

26 * @file

27 * Flash Screen Video encoder

28 * @author Alex Beregszaszi

29 * @author Benjamin Larsson

30 *

31 * A description of the bitstream format for Flash Screen Video version 1/2

32 * is part of the SWF File Format Specification (version 10), which can be

33 * downloaded from http://www.adobe.com/devnet/swf.html.

34 */

36 /*

37 * Encoding ideas: A basic encoder would just use a fixed block size.

38 * Block sizes can be multiples of 16, from 16 to 256. The blocks don't

39 * have to be quadratic. A brute force search with a set of different

40 * block sizes should give a better result than to just use a fixed size.

41 *

42 * TODO:

43 * Don't reencode the frame in brute force mode if the frame is a dupe.

44 * Speed up. Make the difference check faster.

45 */

47 #include <stdio.h>

48 #include <stdlib.h>

49 #include <zlib.h>

51 #include "avcodec.h"

52 #include "internal.h"

53 #include "put_bits.h"

54 #include "bytestream.h"

57 typedef struct FlashSVContext {

58 AVCodecContext *avctx;

59 uint8_t *previous_frame;

60 int image_width, image_height;

61 int block_width, block_height;

62 uint8_t *tmpblock;

63 uint8_t *encbuffer;

64 int block_size;

65 z_stream zstream;

66 int last_key_frame;

67 } FlashSVContext;

69 static int copy_region_enc(uint8_t *sptr, uint8_t *dptr, int dx, int dy,

70 int h, int w, int stride, uint8_t *pfptr)

71 {

72 int i, j;

73 uint8_t *nsptr;

74 uint8_t *npfptr;

75 int diff = 0;

77 for (i = dx + h; i > dx; i--) {

78 nsptr = sptr + i * stride + dy * 3;

79 npfptr = pfptr + i * stride + dy * 3;

80 for (j = 0; j < w * 3; j++) {

81 diff |= npfptr[j] ^ nsptr[j];

82 dptr[j] = nsptr[j];

83 }

84 dptr += w * 3;

85 }

86 if (diff)

87 return 1;

88 return 0;

89 }

91 static av_cold int flashsv_encode_end(AVCodecContext *avctx)

92 {

93 FlashSVContext *s = avctx->priv_data;

95 deflateEnd(&s->zstream);

97 av_freep(&s->encbuffer);

98 av_freep(&s->previous_frame);

99 av_freep(&s->tmpblock);

100

101 av_frame_free(&avctx->coded_frame);

102

103 return 0;

104 }

105

106 static av_cold int flashsv_encode_init(AVCodecContext *avctx)

107 {

108 FlashSVContext *s = avctx->priv_data;

109

110 s->avctx = avctx;

111

112 if (avctx->width > 4095 || avctx->height > 4095) {

113 av_log(avctx, AV_LOG_ERROR,

114 "Input dimensions too large, input must be max 4096x4096 !\n");

115 return AVERROR_INVALIDDATA;

116 }

117

118 // Needed if zlib unused or init aborted before deflateInit

119 memset(&s->zstream, 0, sizeof(z_stream));

120

121 s->last_key_frame = 0;

122

123 s->image_width = avctx->width;

124 s->image_height = avctx->height;

125

126 s->tmpblock = av_mallocz(3 * 256 * 256);

127 s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);

128

129 if (!s->tmpblock || !s->encbuffer) {

130 av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");

131 return AVERROR(ENOMEM);

132 }

133

134 avctx->coded_frame = av_frame_alloc();

135 if (!avctx->coded_frame) {

136 flashsv_encode_end(avctx);

137 return AVERROR(ENOMEM);

138 }

139

140 return 0;

141 }

142

143

144 static int encode_bitstream(FlashSVContext *s, const AVFrame *p, uint8_t *buf,

145 int buf_size, int block_width, int block_height,

146 uint8_t *previous_frame, int *I_frame)

147 {

148

149 PutBitContext pb;

150 int h_blocks, v_blocks, h_part, v_part, i, j;

151 int buf_pos, res;

152 int pred_blocks = 0;

153

154 init_put_bits(&pb, buf, buf_size);

155

156 put_bits(&pb, 4, block_width / 16 - 1);

157 put_bits(&pb, 12, s->image_width);

158 put_bits(&pb, 4, block_height / 16 - 1);

159 put_bits(&pb, 12, s->image_height);

160 flush_put_bits(&pb);

161 buf_pos = 4;

162

163 h_blocks = s->image_width / block_width;

164 h_part = s->image_width % block_width;

165 v_blocks = s->image_height / block_height;

166 v_part = s->image_height % block_height;

167

168 /* loop over all block columns */

169 for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {

170

171 int y_pos = j * block_height; // vertical position in frame

172 int cur_blk_height = (j < v_blocks) ? block_height : v_part;

173

174 /* loop over all block rows */

175 for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {

176 int x_pos = i * block_width; // horizontal position in frame

177 int cur_blk_width = (i < h_blocks) ? block_width : h_part;

178 int ret = Z_OK;

179 uint8_t *ptr = buf + buf_pos;

180

181 /* copy the block to the temp buffer before compression

182 * (if it differs from the previous frame's block) */

183 res = copy_region_enc(p->data[0], s->tmpblock,

184 s->image_height - (y_pos + cur_blk_height + 1),

185 x_pos, cur_blk_height, cur_blk_width,

186 p->linesize[0], previous_frame);

187

188 if (res || *I_frame) {

189 unsigned long zsize = 3 * block_width * block_height;

190 ret = compress2(ptr + 2, &zsize, s->tmpblock,

191 3 * cur_blk_width * cur_blk_height, 9);

192

193 //ret = deflateReset(&s->zstream);

194 if (ret != Z_OK)

195 av_log(s->avctx, AV_LOG_ERROR,

196 "error while compressing block %dx%d\n", i, j);

197

198 bytestream_put_be16(&ptr, zsize);

199 buf_pos += zsize + 2;

200 av_dlog(s->avctx, "buf_pos = %d\n", buf_pos);

201 } else {

202 pred_blocks++;

203 bytestream_put_be16(&ptr, 0);

204 buf_pos += 2;

205 }

206 }

207 }

208

209 if (pred_blocks)

210 *I_frame = 0;

211 else

212 *I_frame = 1;

213

214 return buf_pos;

215 }

216

217

218 static int flashsv_encode_frame(AVCodecContext *avctx, AVPacket *pkt,

219 const AVFrame *pict, int *got_packet)

220 {

221 FlashSVContext * const s = avctx->priv_data;

222 const AVFrame * const p = pict;

223 uint8_t *pfptr;

224 int res;

225 int I_frame = 0;

226 int opt_w = 4, opt_h = 4;

227

228 /* First frame needs to be a keyframe */

229 if (avctx->frame_number == 0) {

230 s->previous_frame = av_mallocz(FFABS(p->linesize[0]) * s->image_height);

231 if (!s->previous_frame) {

232 av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");

233 return AVERROR(ENOMEM);

234 }

235 I_frame = 1;

236 }

237

238 if (p->linesize[0] < 0)

239 pfptr = s->previous_frame - (s->image_height - 1) * p->linesize[0];

240 else

241 pfptr = s->previous_frame;

242

243 /* Check the placement of keyframes */

244 if (avctx->gop_size > 0 &&

245 avctx->frame_number >= s->last_key_frame + avctx->gop_size) {

246 I_frame = 1;

247 }

248

249 if ((res = ff_alloc_packet2(avctx, pkt, s->image_width * s->image_height * 3)) < 0)

250 return res;

251

252 pkt->size = encode_bitstream(s, p, pkt->data, pkt->size, opt_w * 16, opt_h * 16,

253 pfptr, &I_frame);

254

255 //save the current frame

256 if (p->linesize[0] > 0)

257 memcpy(s->previous_frame, p->data[0], s->image_height * p->linesize[0]);

258 else

259 memcpy(s->previous_frame,

260 p->data[0] + p->linesize[0] * (s->image_height - 1),

261 s->image_height * FFABS(p->linesize[0]));

262

263 //mark the frame type so the muxer can mux it correctly

264 if (I_frame) {

265 avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;

266 avctx->coded_frame->key_frame = 1;

267 s->last_key_frame = avctx->frame_number;

268 av_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);

269 } else {

270 avctx->coded_frame->pict_type = AV_PICTURE_TYPE_P;

271 avctx->coded_frame->key_frame = 0;

272 }

273

274 if (avctx->coded_frame->key_frame)

275 pkt->flags |= AV_PKT_FLAG_KEY;

276 *got_packet = 1;

277

278 return 0;

279 }

280

281 AVCodec ff_flashsv_encoder = {

282 .name = "flashsv",

283 .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"),

284 .type = AVMEDIA_TYPE_VIDEO,

285 .id = AV_CODEC_ID_FLASHSV,

286 .priv_data_size = sizeof(FlashSVContext),

287 .init = flashsv_encode_init,

288 .encode2 = flashsv_encode_frame,

289 .close = flashsv_encode_end,

290 .pix_fmts = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },

291 };

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