FFmpeg: libavcodec/tscc2.c Source File

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libavcodec

tscc2.c

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1 /*

2 * TechSmith Screen Codec 2 (aka Dora) 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 * TechSmith Screen Codec 2 decoder

25 */

27 #define BITSTREAM_READER_LE

28 #include "avcodec.h"

29 #include "get_bits.h"

30 #include "bytestream.h"

31 #include "internal.h"

32 #include "tscc2data.h"

34 typedef struct TSCC2Context {

35 AVCodecContext *avctx;

36 AVFrame *pic;

37 int mb_width, mb_height;

38 uint8_t *slice_quants;

39 int quant[2];

40 int q[2][3];

41 GetBitContext gb;

43 VLC dc_vlc, nc_vlc[NUM_VLC_SETS], ac_vlc[NUM_VLC_SETS];

44 int block[16];

45 } TSCC2Context;

47 static av_cold void free_vlcs(TSCC2Context *c)

48 {

49 int i;

51 ff_free_vlc(&c->dc_vlc);

52 for (i = 0; i < NUM_VLC_SETS; i++) {

53 ff_free_vlc(c->nc_vlc + i);

54 ff_free_vlc(c->ac_vlc + i);

55 }

56 }

58 static av_cold int init_vlcs(TSCC2Context *c)

59 {

60 int i, ret;

62 ret = ff_init_vlc_sparse(&c->dc_vlc, 9, DC_VLC_COUNT,

63 tscc2_dc_vlc_bits, 1, 1,

64 tscc2_dc_vlc_codes, 2, 2,

65 tscc2_dc_vlc_syms, 2, 2, INIT_VLC_LE);

66 if (ret)

67 return ret;

69 for (i = 0; i < NUM_VLC_SETS; i++) {

70 ret = ff_init_vlc_sparse(c->nc_vlc + i, 9, 16,

71 tscc2_nc_vlc_bits[i], 1, 1,

72 tscc2_nc_vlc_codes[i], 2, 2,

73 tscc2_nc_vlc_syms, 1, 1, INIT_VLC_LE);

74 if (ret) {

75 free_vlcs(c);

76 return ret;

77 }

78 ret = ff_init_vlc_sparse(c->ac_vlc + i, 9, tscc2_ac_vlc_sizes[i],

79 tscc2_ac_vlc_bits[i], 1, 1,

80 tscc2_ac_vlc_codes[i], 2, 2,

81 tscc2_ac_vlc_syms[i], 2, 2, INIT_VLC_LE);

82 if (ret) {

83 free_vlcs(c);

84 return ret;

85 }

86 }

88 return 0;

89 }

91 #define DEQUANT(val, q) ((q * val + 0x80) >> 8)

92 #define DCT1D(d0, d1, d2, d3, s0, s1, s2, s3, OP) \

93 OP(d0, 5 * ((s0) + (s1) + (s2)) + 2 * (s3)); \

94 OP(d1, 5 * ((s0) - (s2) - (s3)) + 2 * (s1)); \

95 OP(d2, 5 * ((s0) - (s2) + (s3)) - 2 * (s1)); \

96 OP(d3, 5 * ((s0) - (s1) + (s2)) - 2 * (s3)); \

98 #define COL_OP(a, b) a = b

99 #define ROW_OP(a, b) a = ((b) + 0x20) >> 6

100

101 static void tscc2_idct4_put(int *in, int q[3], uint8_t *dst, int stride)

102 {

103 int i;

104 int tblk[4 * 4];

105 int t0, t1, t2, t3;

106

107 for (i = 0; i < 4; i++) {

108 t0 = DEQUANT(q[0 + (i & 1)], in[0 * 4 + i]);

109 t1 = DEQUANT(q[1 + (i & 1)], in[1 * 4 + i]);

110 t2 = DEQUANT(q[0 + (i & 1)], in[2 * 4 + i]);

111 t3 = DEQUANT(q[1 + (i & 1)], in[3 * 4 + i]);

112 DCT1D(tblk[0 * 4 + i], tblk[1 * 4 + i],

113 tblk[2 * 4 + i], tblk[3 * 4 + i],

114 t0, t1, t2, t3, COL_OP);

115 }

116 for (i = 0; i < 4; i++) {

117 DCT1D(dst[0], dst[1], dst[2], dst[3],

118 tblk[i * 4 + 0], tblk[i * 4 + 1],

119 tblk[i * 4 + 2], tblk[i * 4 + 3], ROW_OP);

120 dst += stride;

121 }

122 }

123

124 static int tscc2_decode_mb(TSCC2Context *c, int *q, int vlc_set,

125 uint8_t *dst, int stride, int plane)

126 {

127 GetBitContext *gb = &c->gb;

128 int prev_dc, dc, nc, ac, bpos, val;

129 int i, j, k, l;

130

131 if (get_bits1(gb)) {

132 if (get_bits1(gb)) {

133 val = get_bits(gb, 8);

134 for (i = 0; i < 8; i++, dst += stride)

135 memset(dst, val, 16);

136 } else {

137 if (get_bits_left(gb) < 16 * 8 * 8)

138 return AVERROR_INVALIDDATA;

139 for (i = 0; i < 8; i++) {

140 for (j = 0; j < 16; j++)

141 dst[j] = get_bits(gb, 8);

142 dst += stride;

143 }

144 }

145 return 0;

146 }

147

148 prev_dc = 0;

149 for (j = 0; j < 2; j++) {

150 for (k = 0; k < 4; k++) {

151 if (!(j | k)) {

152 dc = get_bits(gb, 8);

153 } else {

154 dc = get_vlc2(gb, c->dc_vlc.table, 9, 2);

155 if (dc == -1)

156 return AVERROR_INVALIDDATA;

157 if (dc == 0x100)

158 dc = get_bits(gb, 8);

159 }

160 dc = (dc + prev_dc) & 0xFF;

161 prev_dc = dc;

162 c->block[0] = dc;

163

164 nc = get_vlc2(gb, c->nc_vlc[vlc_set].table, 9, 1);

165 if (nc == -1)

166 return AVERROR_INVALIDDATA;

167

168 bpos = 1;

169 memset(c->block + 1, 0, 15 * sizeof(*c->block));

170 for (l = 0; l < nc; l++) {

171 ac = get_vlc2(gb, c->ac_vlc[vlc_set].table, 9, 2);

172 if (ac == -1)

173 return AVERROR_INVALIDDATA;

174 if (ac == 0x1000)

175 ac = get_bits(gb, 12);

176 bpos += ac & 0xF;

177 if (bpos >= 16)

178 return AVERROR_INVALIDDATA;

179 val = sign_extend(ac >> 4, 8);

180 c->block[tscc2_zigzag[bpos++]] = val;

181 }

182 tscc2_idct4_put(c->block, q, dst + k * 4, stride);

183 }

184 dst += 4 * stride;

185 }

186 return 0;

187 }

188

189 static int tscc2_decode_slice(TSCC2Context *c, int mb_y,

190 const uint8_t *buf, int buf_size)

191 {

192 int i, mb_x, q, ret;

193 int off;

194

195 init_get_bits(&c->gb, buf, buf_size * 8);

196

197 for (mb_x = 0; mb_x < c->mb_width; mb_x++) {

198 q = c->slice_quants[mb_x + c->mb_width * mb_y];

199

200 if (q == 0 || q == 3) // skip block

201 continue;

202 for (i = 0; i < 3; i++) {

203 off = mb_x * 16 + mb_y * 8 * c->pic->linesize[i];

204 ret = tscc2_decode_mb(c, c->q[q - 1], c->quant[q - 1] - 2,

205 c->pic->data[i] + off, c->pic->linesize[i], i);

206 if (ret)

207 return ret;

208 }

209 }

210

211 return 0;

212 }

213

214 static int tscc2_decode_frame(AVCodecContext *avctx, void *data,

215 int *got_frame, AVPacket *avpkt)

216 {

217 const uint8_t *buf = avpkt->data;

218 int buf_size = avpkt->size;

219 TSCC2Context *c = avctx->priv_data;

220 GetByteContext gb;

221 uint32_t frame_type, size;

222 int i, val, len, pos = 0;

223 int num_mb = c->mb_width * c->mb_height;

224 int ret;

225

226 bytestream2_init(&gb, buf, buf_size);

227 frame_type = bytestream2_get_byte(&gb);

228 if (frame_type > 1) {

229 av_log(avctx, AV_LOG_ERROR, "Incorrect frame type %d\n", frame_type);

230 return AVERROR_INVALIDDATA;

231 }

232

233 if ((ret = ff_reget_buffer(avctx, c->pic)) < 0) {

234 return ret;

235 }

236

237 if (frame_type == 0) {

238 *got_frame = 1;

239 if ((ret = av_frame_ref(data, c->pic)) < 0)

240 return ret;

241

242 return buf_size;

243 }

244

245 if (bytestream2_get_bytes_left(&gb) < 4) {

246 av_log(avctx, AV_LOG_ERROR, "Frame is too short\n");

247 return AVERROR_INVALIDDATA;

248 }

249

250 c->quant[0] = bytestream2_get_byte(&gb);

251 c->quant[1] = bytestream2_get_byte(&gb);

252 if (c->quant[0] < 2 || c->quant[0] > NUM_VLC_SETS + 1 ||

253 c->quant[1] < 2 || c->quant[1] > NUM_VLC_SETS + 1) {

254 av_log(avctx, AV_LOG_ERROR, "Invalid quantisers %d / %d\n",

255 c->quant[0], c->quant[1]);

256 return AVERROR_INVALIDDATA;

257 }

258

259 for (i = 0; i < 3; i++) {

260 c->q[0][i] = tscc2_quants[c->quant[0] - 2][i];

261 c->q[1][i] = tscc2_quants[c->quant[1] - 2][i];

262 }

263

264 bytestream2_skip(&gb, 1);

265

266 size = bytestream2_get_le32(&gb);

267 if (size > bytestream2_get_bytes_left(&gb)) {

268 av_log(avctx, AV_LOG_ERROR, "Slice properties chunk is too large\n");

269 return AVERROR_INVALIDDATA;

270 }

271

272 for (i = 0; i < size; i++) {

273 val = bytestream2_get_byte(&gb);

274 len = val & 0x3F;

275 val >>= 6;

276 if (pos + len > num_mb) {

277 av_log(avctx, AV_LOG_ERROR, "Too many slice properties\n");

278 return AVERROR_INVALIDDATA;

279 }

280 memset(c->slice_quants + pos, val, len);

281 pos += len;

282 }

283 if (pos < num_mb) {

284 av_log(avctx, AV_LOG_ERROR, "Too few slice properties (%d / %d)\n",

285 pos, num_mb);

286 return AVERROR_INVALIDDATA;

287 }

288

289 for (i = 0; i < c->mb_height; i++) {

290 size = bytestream2_peek_byte(&gb);

291 if (size & 1) {

292 size = bytestream2_get_byte(&gb) - 1;

293 } else {

294 size = bytestream2_get_le32(&gb) >> 1;

295 }

296 if (!size) {

297 int skip_row = 1, j, off = i * c->mb_width;

298 for (j = 0; j < c->mb_width; j++) {

299 if (c->slice_quants[off + j] == 1 ||

300 c->slice_quants[off + j] == 2) {

301 skip_row = 0;

302 break;

303 }

304 }

305 if (!skip_row) {

306 av_log(avctx, AV_LOG_ERROR, "Non-skip row with zero size\n");

307 return AVERROR_INVALIDDATA;

308 }

309 }

310 if (bytestream2_get_bytes_left(&gb) < size) {

311 av_log(avctx, AV_LOG_ERROR, "Invalid slice size (%d/%d)\n",

312 size, bytestream2_get_bytes_left(&gb));

313 return AVERROR_INVALIDDATA;

314 }

315 ret = tscc2_decode_slice(c, i, buf + bytestream2_tell(&gb), size);

316 if (ret) {

317 av_log(avctx, AV_LOG_ERROR, "Error decoding slice %d\n", i);

318 return ret;

319 }

320 bytestream2_skip(&gb, size);

321 }

322

323 *got_frame = 1;

324 if ((ret = av_frame_ref(data, c->pic)) < 0)

325 return ret;

326

327 /* always report that the buffer was completely consumed */

328 return buf_size;

329 }

330

331 static av_cold int tscc2_decode_end(AVCodecContext *avctx)

332 {

333 TSCC2Context * const c = avctx->priv_data;

334

335 av_frame_free(&c->pic);

336 av_freep(&c->slice_quants);

337 free_vlcs(c);

338

339 return 0;

340 }

341

342 static av_cold int tscc2_decode_init(AVCodecContext *avctx)

343 {

344 TSCC2Context * const c = avctx->priv_data;

345 int ret;

346

347 c->avctx = avctx;

348

349 avctx->pix_fmt = AV_PIX_FMT_YUV444P;

350

351 if ((ret = init_vlcs(c)) < 0) {

352 av_log(avctx, AV_LOG_ERROR, "Cannot initialise VLCs\n");

353 return ret;

354 }

355

356 c->mb_width = FFALIGN(avctx->width, 16) >> 4;

357 c->mb_height = FFALIGN(avctx->height, 8) >> 3;

358 c->slice_quants = av_malloc(c->mb_width * c->mb_height);

359 if (!c->slice_quants) {

360 av_log(avctx, AV_LOG_ERROR, "Cannot allocate slice information\n");

361 free_vlcs(c);

362 return AVERROR(ENOMEM);

363 }

364

365 c->pic = av_frame_alloc();

366 if (!c->pic) {

367 tscc2_decode_end(avctx);

368 return AVERROR(ENOMEM);

369 }

370

371 return 0;

372 }

373

374 AVCodec ff_tscc2_decoder = {

375 .name = "tscc2",

376 .type = AVMEDIA_TYPE_VIDEO,

377 .id = AV_CODEC_ID_TSCC2,

378 .priv_data_size = sizeof(TSCC2Context),

379 .init = tscc2_decode_init,

380 .close = tscc2_decode_end,

381 .decode = tscc2_decode_frame,

382 .capabilities = CODEC_CAP_DR1,

383 .long_name = NULL_IF_CONFIG_SMALL("TechSmith Screen Codec 2"),

384 };

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