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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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
24 * Lagarith lossless decoder
25 * @author Nathan Caldwell
32 #include "lagarithrac.h"
35 enum LagarithFrameType {
36 FRAME_RAW = 1, /**< uncompressed */
37 FRAME_U_RGB24 = 2, /**< unaligned RGB24 */
38 FRAME_ARITH_YUY2 = 3, /**< arithmetic coded YUY2 */
39 FRAME_ARITH_RGB24 = 4, /**< arithmetic coded RGB24 */
40 FRAME_SOLID_GRAY = 5, /**< solid grayscale color frame */
41 FRAME_SOLID_COLOR = 6, /**< solid non-grayscale color frame */
42 FRAME_OLD_ARITH_RGB = 7, /**< obsolete arithmetic coded RGB (no longer encoded by upstream since version 1.1.0) */
43 FRAME_ARITH_RGBA = 8, /**< arithmetic coded RGBA */
44 FRAME_SOLID_RGBA = 9, /**< solid RGBA color frame */
45 FRAME_ARITH_YV12 = 10, /**< arithmetic coded YV12 */
46 FRAME_REDUCED_RES = 11, /**< reduced resolution YV12 frame */
49 typedef struct LagarithContext {
50 AVCodecContext *avctx;
53 int zeros; /**< number of consecutive zero bytes encountered */
54 int zeros_rem; /**< number of zero bytes remaining to output */
60 * Compute the 52bit mantissa of 1/(double)denom.
61 * This crazy format uses floats in an entropy coder and we have to match x86
62 * rounding exactly, thus ordinary floats aren't portable enough.
63 * @param denom denominator
64 * @return 52bit mantissa
67 static uint64_t softfloat_reciprocal(uint32_t denom)
69 int shift = av_log2(denom - 1) + 1;
70 uint64_t ret = (1ULL << 52) / denom;
71 uint64_t err = (1ULL << 52) - ret * denom;
75 return ret + err / denom;
79 * (uint32_t)(x*f), where f has the given mantissa, and exponent 0
80 * Used in combination with softfloat_reciprocal computes x/(double)denom.
81 * @param x 32bit integer factor
82 * @param mantissa mantissa of f with exponent 0
83 * @return 32bit integer value (x*f)
84 * @see softfloat_reciprocal
86 static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
88 uint64_t l = x * (mantissa & 0xffffffff);
89 uint64_t h = x * (mantissa >> 32);
92 l += 1 << av_log2(h >> 21);
97 static uint8_t lag_calc_zero_run(int8_t x)
99 return (x << 1) ^ (x >> 7);
102 static int lag_decode_prob(GetBitContext *gb, uint32_t *value)
104 static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };
111 for (i = 0; i < 7; i++) {
120 if (bits < 0 || bits > 31) {
123 } else if (bits == 0) {
128 val = get_bits_long(gb, bits);
136 static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)
138 int i, j, scale_factor;
139 unsigned prob, cumulative_target;
140 unsigned cumul_prob = 0;
141 unsigned scaled_cumul_prob = 0;
144 rac->prob[257] = UINT_MAX;
145 /* Read probabilities from bitstream */
146 for (i = 1; i < 257; i++) {
147 if (lag_decode_prob(gb, &rac->prob[i]) < 0) {
148 av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");
151 if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {
152 av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");
155 cumul_prob += rac->prob[i];
157 if (lag_decode_prob(gb, &prob)) {
158 av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");
163 for (j = 0; j < prob; j++)
169 av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
173 /* Scale probabilities so cumulative probability is an even power of 2. */
174 scale_factor = av_log2(cumul_prob);
176 if (cumul_prob & (cumul_prob - 1)) {
177 uint64_t mul = softfloat_reciprocal(cumul_prob);
178 for (i = 1; i < 257; i++) {
179 rac->prob[i] = softfloat_mul(rac->prob[i], mul);
180 scaled_cumul_prob += rac->prob[i];
184 cumulative_target = 1 << scale_factor;
186 if (scaled_cumul_prob > cumulative_target) {
187 av_log(rac->avctx, AV_LOG_ERROR,
188 "Scaled probabilities are larger than target!\n");
192 scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
194 for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
199 /* Comment from reference source:
200 * if (b & 0x80 == 0) { // order of operations is 'wrong'; it has been left this way
201 * // since the compression change is negligible and fixing it
202 * // breaks backwards compatibility
203 * b =- (signed int)b;
213 rac->scale = scale_factor;
215 /* Fill probability array with cumulative probability for each symbol. */
216 for (i = 1; i < 257; i++)
217 rac->prob[i] += rac->prob[i - 1];
222 static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
223 uint8_t *diff, int w, int *left,
226 /* This is almost identical to add_hfyu_median_prediction in dsputil.h.
227 * However the &0xFF on the gradient predictor yealds incorrect output
236 for (i = 0; i < w; i++) {
237 l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
246 static void lag_pred_line(LagarithContext *l, uint8_t *buf,
247 int width, int stride, int line)
252 /* Left prediction only for first line */
253 L = l->dsp.add_hfyu_left_prediction(buf, buf,
256 /* Left pixel is actually prev_row[width] */
257 L = buf[width - stride - 1];
260 /* Second line, left predict first pixel, the rest of the line is median predicted
261 * NOTE: In the case of RGB this pixel is top predicted */
262 TL = l->avctx->pix_fmt == AV_PIX_FMT_YUV420P ? buf[-stride] : L;
264 /* Top left is 2 rows back, last pixel */
265 TL = buf[width - (2 * stride) - 1];
268 add_lag_median_prediction(buf, buf - stride, buf,
273 static void lag_pred_line_yuy2(LagarithContext *l, uint8_t *buf,
274 int width, int stride, int line,
283 l->dsp.add_hfyu_left_prediction(buf, buf, width, 0);
289 const int HEAD = is_luma ? 4 : 2;
292 L = buf[width - stride - 1];
293 TL = buf[HEAD - stride - 1];
294 for (i = 0; i < HEAD; i++) {
298 for (; i<width; i++) {
299 L = mid_pred(L&0xFF, buf[i-stride], (L + buf[i-stride] - TL)&0xFF) + buf[i];
304 TL = buf[width - (2 * stride) - 1];
305 L = buf[width - stride - 1];
306 l->dsp.add_hfyu_median_prediction(buf, buf - stride, buf, width,
311 static int lag_decode_line(LagarithContext *l, lag_rac *rac,
312 uint8_t *dst, int width, int stride,
321 /* Output any zeros remaining from the previous run */
324 int count = FFMIN(l->zeros_rem, width - i);
325 memset(dst + i, 0, count);
327 l->zeros_rem -= count;
331 dst[i] = lag_get_rac(rac);
340 if (l->zeros == esc_count) {
341 int index = lag_get_rac(rac);
346 l->zeros_rem = lag_calc_zero_run(index);
353 static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
354 const uint8_t *src, const uint8_t *src_end,
355 int width, int esc_count)
359 uint8_t zero_run = 0;
360 const uint8_t *src_start = src;
361 uint8_t mask1 = -(esc_count < 2);
362 uint8_t mask2 = -(esc_count < 3);
363 uint8_t *end = dst + (width - 2);
367 count = FFMIN(l->zeros_rem, width - i);
368 if (end - dst < count) {
369 av_log(l->avctx, AV_LOG_ERROR, "Too many zeros remaining.\n");
370 return AVERROR_INVALIDDATA;
373 memset(dst, 0, count);
374 l->zeros_rem -= count;
380 while (!zero_run && dst + i < end) {
382 if (i+2 >= src_end - src)
383 return AVERROR_INVALIDDATA;
385 !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
392 l->zeros_rem = lag_calc_zero_run(src[i]);
402 return src - src_start;
407 static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
408 int width, int height, int stride,
409 const uint8_t *src, int src_size)
418 const uint8_t *src_end = src + src_size;
420 rac.avctx = l->avctx;
424 return AVERROR_INVALIDDATA;
428 length = width * height;
430 return AVERROR_INVALIDDATA;
431 if (esc_count && AV_RL32(src + 1) < length) {
432 length = AV_RL32(src + 1);
436 init_get_bits(&gb, src + offset, src_size * 8);
438 if (lag_read_prob_header(&rac, &gb) < 0)
441 ff_lag_rac_init(&rac, &gb, length - stride);
443 for (i = 0; i < height; i++)
444 read += lag_decode_line(l, &rac, dst + (i * stride), width,
448 av_log(l->avctx, AV_LOG_WARNING,
449 "Output more bytes than length (%d of %d)\n", read,
451 } else if (esc_count < 8) {
454 /* Zero run coding only, no range coding. */
455 for (i = 0; i < height; i++) {
456 int res = lag_decode_zero_run_line(l, dst + (i * stride), src,
457 src_end, width, esc_count);
463 if (src_size < width * height)
464 return AVERROR_INVALIDDATA; // buffer not big enough
465 /* Plane is stored uncompressed */
466 for (i = 0; i < height; i++) {
467 memcpy(dst + (i * stride), src, width);
471 } else if (esc_count == 0xff) {
472 /* Plane is a solid run of given value */
473 for (i = 0; i < height; i++)
474 memset(dst + i * stride, src[1], width);
475 /* Do not apply prediction.
476 Note: memset to 0 above, setting first value to src[1]
477 and applying prediction gives the same result. */
480 av_log(l->avctx, AV_LOG_ERROR,
481 "Invalid zero run escape code! (%#x)\n", esc_count);
485 if (l->avctx->pix_fmt != AV_PIX_FMT_YUV422P) {
486 for (i = 0; i < height; i++) {
487 lag_pred_line(l, dst, width, stride, i);
491 for (i = 0; i < height; i++) {
492 lag_pred_line_yuy2(l, dst, width, stride, i,
493 width == l->avctx->width);
503 * @param avctx codec context
504 * @param data output AVFrame
505 * @param data_size size of output data or 0 if no picture is returned
506 * @param avpkt input packet
507 * @return number of consumed bytes on success or negative if decode fails
509 static int lag_decode_frame(AVCodecContext *avctx,
510 void *data, int *got_frame, AVPacket *avpkt)
512 const uint8_t *buf = avpkt->data;
513 unsigned int buf_size = avpkt->size;
514 LagarithContext *l = avctx->priv_data;
515 AVFrame *const p = &l->picture;
516 uint8_t frametype = 0;
517 uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
519 uint8_t *srcs[4], *dst;
520 int i, j, planes = 3;
523 AVFrame *picture = data;
526 ff_thread_release_buffer(avctx, p);
533 offset_gu = AV_RL32(buf + 1);
534 offset_bv = AV_RL32(buf + 5);
537 case FRAME_SOLID_RGBA:
538 avctx->pix_fmt = AV_PIX_FMT_RGB32;
539 case FRAME_SOLID_GRAY:
540 if (frametype == FRAME_SOLID_GRAY)
541 if (avctx->bits_per_coded_sample == 24) {
542 avctx->pix_fmt = AV_PIX_FMT_RGB24;
544 avctx->pix_fmt = AV_PIX_FMT_0RGB32;
548 if ((ret = ff_thread_get_buffer(avctx, p)) < 0) {
549 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
554 if (frametype == FRAME_SOLID_RGBA) {
555 for (j = 0; j < avctx->height; j++) {
556 for (i = 0; i < avctx->width; i++)
557 AV_WN32(dst + i * 4, offset_gu);
558 dst += p->linesize[0];
561 for (j = 0; j < avctx->height; j++) {
562 memset(dst, buf[1], avctx->width * planes);
563 dst += p->linesize[0];
567 case FRAME_ARITH_RGBA:
568 avctx->pix_fmt = AV_PIX_FMT_RGB32;
571 offs[3] = AV_RL32(buf + 9);
572 case FRAME_ARITH_RGB24:
574 if (frametype == FRAME_ARITH_RGB24 || frametype == FRAME_U_RGB24)
575 avctx->pix_fmt = AV_PIX_FMT_RGB24;
577 if ((ret = ff_thread_get_buffer(avctx, p)) < 0) {
578 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
586 if (!l->rgb_planes) {
587 l->rgb_stride = FFALIGN(avctx->width, 16);
588 l->rgb_planes = av_malloc(l->rgb_stride * avctx->height * 4 + 16);
589 if (!l->rgb_planes) {
590 av_log(avctx, AV_LOG_ERROR, "cannot allocate temporary buffer\n");
591 return AVERROR(ENOMEM);
594 for (i = 0; i < planes; i++)
595 srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;
596 for (i = 0; i < planes; i++)
597 if (buf_size <= offs[i]) {
598 av_log(avctx, AV_LOG_ERROR,
599 "Invalid frame offsets\n");
600 return AVERROR_INVALIDDATA;
603 for (i = 0; i < planes; i++)
604 lag_decode_arith_plane(l, srcs[i],
605 avctx->width, avctx->height,
606 -l->rgb_stride, buf + offs[i],
609 for (i = 0; i < planes; i++)
610 srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;
611 for (j = 0; j < avctx->height; j++) {
612 for (i = 0; i < avctx->width; i++) {
619 if (frametype == FRAME_ARITH_RGBA) {
621 AV_WN32(dst + i * 4, MKBETAG(a, r, g, b));
628 dst += p->linesize[0];
629 for (i = 0; i < planes; i++)
630 srcs[i] += l->rgb_stride;
633 case FRAME_ARITH_YUY2:
634 avctx->pix_fmt = AV_PIX_FMT_YUV422P;
636 if ((ret = ff_thread_get_buffer(avctx, p)) < 0) {
637 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
641 if (offset_ry >= buf_size ||
642 offset_gu >= buf_size ||
643 offset_bv >= buf_size) {
644 av_log(avctx, AV_LOG_ERROR,
645 "Invalid frame offsets\n");
646 return AVERROR_INVALIDDATA;
649 lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
650 p->linesize[0], buf + offset_ry,
651 buf_size - offset_ry);
652 lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
653 avctx->height, p->linesize[1],
654 buf + offset_gu, buf_size - offset_gu);
655 lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
656 avctx->height, p->linesize[2],
657 buf + offset_bv, buf_size - offset_bv);
659 case FRAME_ARITH_YV12:
660 avctx->pix_fmt = AV_PIX_FMT_YUV420P;
662 if ((ret = ff_thread_get_buffer(avctx, p)) < 0) {
663 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
666 if (buf_size <= offset_ry || buf_size <= offset_gu || buf_size <= offset_bv) {
667 return AVERROR_INVALIDDATA;
670 if (offset_ry >= buf_size ||
671 offset_gu >= buf_size ||
672 offset_bv >= buf_size) {
673 av_log(avctx, AV_LOG_ERROR,
674 "Invalid frame offsets\n");
675 return AVERROR_INVALIDDATA;
678 lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
679 p->linesize[0], buf + offset_ry,
680 buf_size - offset_ry);
681 lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
682 avctx->height / 2, p->linesize[2],
683 buf + offset_gu, buf_size - offset_gu);
684 lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
685 avctx->height / 2, p->linesize[1],
686 buf + offset_bv, buf_size - offset_bv);
689 av_log(avctx, AV_LOG_ERROR,
690 "Unsupported Lagarith frame type: %#x\n", frametype);
691 return AVERROR_PATCHWELCOME;
700 static av_cold int lag_decode_init(AVCodecContext *avctx)
702 LagarithContext *l = avctx->priv_data;
705 ff_dsputil_init(&l->dsp, avctx);
710 static av_cold int lag_decode_end(AVCodecContext *avctx)
712 LagarithContext *l = avctx->priv_data;
714 if (l->picture.data[0])
715 ff_thread_release_buffer(avctx, &l->picture);
716 av_freep(&l->rgb_planes);
721 AVCodec ff_lagarith_decoder = {
723 .type = AVMEDIA_TYPE_VIDEO,
724 .id = AV_CODEC_ID_LAGARITH,
725 .priv_data_size = sizeof(LagarithContext),
726 .init = lag_decode_init,
727 .close = lag_decode_end,
728 .decode = lag_decode_frame,
729 .capabilities = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
730 .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),