2 * Lagarith lossless decoder
3 * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
5 * This file is part of FFmpeg.
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8 * modify it under the terms of the GNU Lesser General Public
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19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * Lagarith lossless decoder
25 * @author Nathan Caldwell
32 #include "lagarithrac.h"
34 enum LagarithFrameType {
35 FRAME_RAW = 1, /**< uncompressed */
36 FRAME_U_RGB24 = 2, /**< unaligned RGB24 */
37 FRAME_ARITH_YUY2 = 3, /**< arithmetic coded YUY2 */
38 FRAME_ARITH_RGB24 = 4, /**< arithmetic coded RGB24 */
39 FRAME_SOLID_GRAY = 5, /**< solid grayscale color frame */
40 FRAME_SOLID_COLOR = 6, /**< solid non-grayscale color frame */
41 FRAME_OLD_ARITH_RGB = 7, /**< obsolete arithmetic coded RGB (no longer encoded by upstream since version 1.1.0) */
42 FRAME_ARITH_RGBA = 8, /**< arithmetic coded RGBA */
43 FRAME_SOLID_RGBA = 9, /**< solid RGBA color frame */
44 FRAME_ARITH_YV12 = 10, /**< arithmetic coded YV12 */
45 FRAME_REDUCED_RES = 11, /**< reduced resolution YV12 frame */
48 typedef struct LagarithContext {
49 AVCodecContext *avctx;
52 int zeros; /**< number of consecutive zero bytes encountered */
53 int zeros_rem; /**< number of zero bytes remaining to output */
59 * Compute the 52bit mantissa of 1/(double)denom.
60 * This crazy format uses floats in an entropy coder and we have to match x86
61 * rounding exactly, thus ordinary floats aren't portable enough.
62 * @param denom denominator
63 * @return 52bit mantissa
66 static uint64_t softfloat_reciprocal(uint32_t denom)
68 int shift = av_log2(denom - 1) + 1;
69 uint64_t ret = (1ULL << 52) / denom;
70 uint64_t err = (1ULL << 52) - ret * denom;
74 return ret + err / denom;
78 * (uint32_t)(x*f), where f has the given mantissa, and exponent 0
79 * Used in combination with softfloat_reciprocal computes x/(double)denom.
80 * @param x 32bit integer factor
81 * @param mantissa mantissa of f with exponent 0
82 * @return 32bit integer value (x*f)
83 * @see softfloat_reciprocal
85 static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
87 uint64_t l = x * (mantissa & 0xffffffff);
88 uint64_t h = x * (mantissa >> 32);
91 l += 1 << av_log2(h >> 21);
96 static uint8_t lag_calc_zero_run(int8_t x)
98 return (x << 1) ^ (x >> 7);
101 static int lag_decode_prob(GetBitContext *gb, uint32_t *value)
103 static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };
110 for (i = 0; i < 7; i++) {
119 if (bits < 0 || bits > 31) {
122 } else if (bits == 0) {
127 val = get_bits_long(gb, bits);
135 static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)
137 int i, j, scale_factor;
138 unsigned prob, cumulative_target;
139 unsigned cumul_prob = 0;
140 unsigned scaled_cumul_prob = 0;
143 rac->prob[257] = UINT_MAX;
144 /* Read probabilities from bitstream */
145 for (i = 1; i < 257; i++) {
146 if (lag_decode_prob(gb, &rac->prob[i]) < 0) {
147 av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");
150 if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {
151 av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");
154 cumul_prob += rac->prob[i];
156 if (lag_decode_prob(gb, &prob)) {
157 av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");
162 for (j = 0; j < prob; j++)
168 av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
172 /* Scale probabilities so cumulative probability is an even power of 2. */
173 scale_factor = av_log2(cumul_prob);
175 if (cumul_prob & (cumul_prob - 1)) {
176 uint64_t mul = softfloat_reciprocal(cumul_prob);
177 for (i = 1; i < 257; i++) {
178 rac->prob[i] = softfloat_mul(rac->prob[i], mul);
179 scaled_cumul_prob += rac->prob[i];
183 cumulative_target = 1 << scale_factor;
185 if (scaled_cumul_prob > cumulative_target) {
186 av_log(rac->avctx, AV_LOG_ERROR,
187 "Scaled probabilities are larger than target!\n");
191 scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
193 for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
198 /* Comment from reference source:
199 * if (b & 0x80 == 0) { // order of operations is 'wrong'; it has been left this way
200 * // since the compression change is negligable and fixing it
201 * // breaks backwards compatibilty
202 * b =- (signed int)b;
212 rac->scale = scale_factor;
214 /* Fill probability array with cumulative probability for each symbol. */
215 for (i = 1; i < 257; i++)
216 rac->prob[i] += rac->prob[i - 1];
221 static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
222 uint8_t *diff, int w, int *left,
225 /* This is almost identical to add_hfyu_median_prediction in dsputil.h.
226 * However the &0xFF on the gradient predictor yealds incorrect output
235 for (i = 0; i < w; i++) {
236 l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
245 static void lag_pred_line(LagarithContext *l, uint8_t *buf,
246 int width, int stride, int line)
251 /* Left prediction only for first line */
252 L = l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1,
255 /* Left pixel is actually prev_row[width] */
256 L = buf[width - stride - 1];
259 /* Second line, left predict first pixel, the rest of the line is median predicted
260 * NOTE: In the case of RGB this pixel is top predicted */
261 TL = l->avctx->pix_fmt == PIX_FMT_YUV420P ? buf[-stride] : L;
263 /* Top left is 2 rows back, last pixel */
264 TL = buf[width - (2 * stride) - 1];
267 add_lag_median_prediction(buf, buf - stride, buf,
272 static int lag_decode_line(LagarithContext *l, lag_rac *rac,
273 uint8_t *dst, int width, int stride,
282 /* Output any zeros remaining from the previous run */
285 int count = FFMIN(l->zeros_rem, width - i);
286 memset(dst + i, 0, count);
288 l->zeros_rem -= count;
292 dst[i] = lag_get_rac(rac);
301 if (l->zeros == esc_count) {
302 int index = lag_get_rac(rac);
307 l->zeros_rem = lag_calc_zero_run(index);
314 static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
315 const uint8_t *src, const uint8_t *src_end,
316 int width, int esc_count)
320 uint8_t zero_run = 0;
321 const uint8_t *src_start = src;
322 uint8_t mask1 = -(esc_count < 2);
323 uint8_t mask2 = -(esc_count < 3);
324 uint8_t *end = dst + (width - 2);
328 count = FFMIN(l->zeros_rem, width - i);
329 if(end - dst < count) {
330 av_log(l->avctx, AV_LOG_ERROR, "too many zeros remaining\n");
331 return AVERROR_INVALIDDATA;
333 memset(dst, 0, count);
334 l->zeros_rem -= count;
340 while (!zero_run && dst + i < end) {
342 if (i+2 >= src_end - src)
343 return AVERROR_INVALIDDATA;
345 !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
352 l->zeros_rem = lag_calc_zero_run(src[i]);
362 return src - src_start;
367 static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
368 int width, int height, int stride,
369 const uint8_t *src, int src_size)
378 const uint8_t *src_end = src + src_size;
380 rac.avctx = l->avctx;
384 return AVERROR_INVALIDDATA;
388 length = width * height;
390 return AVERROR_INVALIDDATA;
391 if (esc_count && AV_RL32(src + 1) < length) {
392 length = AV_RL32(src + 1);
396 init_get_bits(&gb, src + offset, src_size * 8);
398 if (lag_read_prob_header(&rac, &gb) < 0)
401 ff_lag_rac_init(&rac, &gb, length - stride);
403 for (i = 0; i < height; i++)
404 read += lag_decode_line(l, &rac, dst + (i * stride), width,
408 av_log(l->avctx, AV_LOG_WARNING,
409 "Output more bytes than length (%d of %d)\n", read,
411 } else if (esc_count < 8) {
414 /* Zero run coding only, no range coding. */
415 for (i = 0; i < height; i++) {
416 int res = lag_decode_zero_run_line(l, dst + (i * stride), src,
417 src_end, width, esc_count);
423 if (src_size < width * height)
424 return AVERROR_INVALIDDATA; // buffer not big enough
425 /* Plane is stored uncompressed */
426 for (i = 0; i < height; i++) {
427 memcpy(dst + (i * stride), src, width);
431 } else if (esc_count == 0xff) {
432 /* Plane is a solid run of given value */
433 for (i = 0; i < height; i++)
434 memset(dst + i * stride, src[1], width);
435 /* Do not apply prediction.
436 Note: memset to 0 above, setting first value to src[1]
437 and applying prediction gives the same result. */
440 av_log(l->avctx, AV_LOG_ERROR,
441 "Invalid zero run escape code! (%#x)\n", esc_count);
445 for (i = 0; i < height; i++) {
446 lag_pred_line(l, dst, width, stride, i);
455 * @param avctx codec context
456 * @param data output AVFrame
457 * @param data_size size of output data or 0 if no picture is returned
458 * @param avpkt input packet
459 * @return number of consumed bytes on success or negative if decode fails
461 static int lag_decode_frame(AVCodecContext *avctx,
462 void *data, int *data_size, AVPacket *avpkt)
464 const uint8_t *buf = avpkt->data;
465 unsigned int buf_size = avpkt->size;
466 LagarithContext *l = avctx->priv_data;
467 AVFrame *const p = &l->picture;
468 uint8_t frametype = 0;
469 uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
471 uint8_t *srcs[4], *dst;
472 int i, j, planes = 3;
474 AVFrame *picture = data;
477 avctx->release_buffer(avctx, p);
484 offset_gu = AV_RL32(buf + 1);
485 offset_bv = AV_RL32(buf + 5);
488 case FRAME_SOLID_RGBA:
489 avctx->pix_fmt = PIX_FMT_RGB32;
491 if (avctx->get_buffer(avctx, p) < 0) {
492 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
497 for (j = 0; j < avctx->height; j++) {
498 for (i = 0; i < avctx->width; i++)
499 AV_WN32(dst + i * 4, offset_gu);
500 dst += p->linesize[0];
503 case FRAME_ARITH_RGBA:
504 avctx->pix_fmt = PIX_FMT_RGB32;
507 offs[3] = AV_RL32(buf + 9);
508 case FRAME_ARITH_RGB24:
510 if (frametype == FRAME_ARITH_RGB24 || frametype == FRAME_U_RGB24)
511 avctx->pix_fmt = PIX_FMT_RGB24;
513 if (avctx->get_buffer(avctx, p) < 0) {
514 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
522 if (!l->rgb_planes) {
523 l->rgb_stride = FFALIGN(avctx->width, 16);
524 l->rgb_planes = av_malloc(l->rgb_stride * avctx->height * planes + 16);
525 if (!l->rgb_planes) {
526 av_log(avctx, AV_LOG_ERROR, "cannot allocate temporary buffer\n");
527 return AVERROR(ENOMEM);
530 for (i = 0; i < planes; i++)
531 srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;
532 for (i = 0; i < planes; i++)
533 if (buf_size <= offs[i]) {
534 av_log(avctx, AV_LOG_ERROR,
535 "Invalid frame offsets\n");
536 return AVERROR_INVALIDDATA;
539 for (i = 0; i < planes; i++)
540 lag_decode_arith_plane(l, srcs[i],
541 avctx->width, avctx->height,
542 -l->rgb_stride, buf + offs[i],
545 for (i = 0; i < planes; i++)
546 srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;
547 for (j = 0; j < avctx->height; j++) {
548 for (i = 0; i < avctx->width; i++) {
555 if (frametype == FRAME_ARITH_RGBA) {
557 AV_WN32(dst + i * 4, MKBETAG(a, r, g, b));
564 dst += p->linesize[0];
565 for (i = 0; i < planes; i++)
566 srcs[i] += l->rgb_stride;
569 case FRAME_ARITH_YV12:
570 avctx->pix_fmt = PIX_FMT_YUV420P;
572 if (avctx->get_buffer(avctx, p) < 0) {
573 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
576 if (buf_size <= offset_ry || buf_size <= offset_gu || buf_size <= offset_bv) {
577 return AVERROR_INVALIDDATA;
580 if (offset_ry >= buf_size ||
581 offset_gu >= buf_size ||
582 offset_bv >= buf_size) {
583 av_log(avctx, AV_LOG_ERROR,
584 "Invalid frame offsets\n");
585 return AVERROR_INVALIDDATA;
588 lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
589 p->linesize[0], buf + offset_ry,
590 buf_size - offset_ry);
591 lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
592 avctx->height / 2, p->linesize[2],
593 buf + offset_gu, buf_size - offset_gu);
594 lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
595 avctx->height / 2, p->linesize[1],
596 buf + offset_bv, buf_size - offset_bv);
599 av_log(avctx, AV_LOG_ERROR,
600 "Unsupported Lagarith frame type: %#x\n", frametype);
605 *data_size = sizeof(AVFrame);
610 static av_cold int lag_decode_init(AVCodecContext *avctx)
612 LagarithContext *l = avctx->priv_data;
615 ff_dsputil_init(&l->dsp, avctx);
620 static av_cold int lag_decode_end(AVCodecContext *avctx)
622 LagarithContext *l = avctx->priv_data;
624 if (l->picture.data[0])
625 avctx->release_buffer(avctx, &l->picture);
626 av_freep(&l->rgb_planes);
631 AVCodec ff_lagarith_decoder = {
633 .type = AVMEDIA_TYPE_VIDEO,
634 .id = CODEC_ID_LAGARITH,
635 .priv_data_size = sizeof(LagarithContext),
636 .init = lag_decode_init,
637 .close = lag_decode_end,
638 .decode = lag_decode_frame,
639 .capabilities = CODEC_CAP_DR1,
640 .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),