2 * Lagarith lossless decoder
3 * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
5 * This file is part of Libav.
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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)
250 /* Left pixel is actually prev_row[width] */
251 L = buf[width - stride - 1];
253 /* Left prediction only for first line */
254 L = l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1,
257 } else if (line == 1) {
258 /* Second line, left predict first pixel, the rest of the line is median predicted
259 * NOTE: In the case of RGB this pixel is top predicted */
260 TL = l->avctx->pix_fmt == PIX_FMT_YUV420P ? buf[-stride] : L;
262 /* Top left is 2 rows back, last pixel */
263 TL = buf[width - (2 * stride) - 1];
266 add_lag_median_prediction(buf, buf - stride, buf,
270 static int lag_decode_line(LagarithContext *l, lag_rac *rac,
271 uint8_t *dst, int width, int stride,
280 /* Output any zeros remaining from the previous run */
283 int count = FFMIN(l->zeros_rem, width - i);
284 memset(dst + i, 0, count);
286 l->zeros_rem -= count;
290 dst[i] = lag_get_rac(rac);
299 if (l->zeros == esc_count) {
300 int index = lag_get_rac(rac);
305 l->zeros_rem = lag_calc_zero_run(index);
312 static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
313 const uint8_t *src, int width,
318 uint8_t zero_run = 0;
319 const uint8_t *start = src;
320 uint8_t mask1 = -(esc_count < 2);
321 uint8_t mask2 = -(esc_count < 3);
322 uint8_t *end = dst + (width - 2);
326 count = FFMIN(l->zeros_rem, width - i);
327 memset(dst, 0, count);
328 l->zeros_rem -= count;
334 while (!zero_run && dst + i < end) {
337 !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
344 l->zeros_rem = lag_calc_zero_run(src[i]);
358 static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
359 int width, int height, int stride,
360 const uint8_t *src, int src_size)
366 int esc_count = src[0];
370 rac.avctx = l->avctx;
374 length = width * height;
375 if (esc_count && AV_RL32(src + 1) < length) {
376 length = AV_RL32(src + 1);
380 init_get_bits(&gb, src + offset, src_size * 8);
382 if (lag_read_prob_header(&rac, &gb) < 0)
385 ff_lag_rac_init(&rac, &gb, length - stride);
387 for (i = 0; i < height; i++)
388 read += lag_decode_line(l, &rac, dst + (i * stride), width,
392 av_log(l->avctx, AV_LOG_WARNING,
393 "Output more bytes than length (%d of %d)\n", read,
395 } else if (esc_count < 8) {
398 /* Zero run coding only, no range coding. */
399 for (i = 0; i < height; i++)
400 src += lag_decode_zero_run_line(l, dst + (i * stride), src,
403 /* Plane is stored uncompressed */
404 for (i = 0; i < height; i++) {
405 memcpy(dst + (i * stride), src, width);
409 } else if (esc_count == 0xff) {
410 /* Plane is a solid run of given value */
411 for (i = 0; i < height; i++)
412 memset(dst + i * stride, src[1], width);
413 /* Do not apply prediction.
414 Note: memset to 0 above, setting first value to src[1]
415 and applying prediction gives the same result. */
418 av_log(l->avctx, AV_LOG_ERROR,
419 "Invalid zero run escape code! (%#x)\n", esc_count);
423 for (i = 0; i < height; i++) {
424 lag_pred_line(l, dst, width, stride, i);
433 * @param avctx codec context
434 * @param data output AVFrame
435 * @param data_size size of output data or 0 if no picture is returned
436 * @param avpkt input packet
437 * @return number of consumed bytes on success or negative if decode fails
439 static int lag_decode_frame(AVCodecContext *avctx,
440 void *data, int *data_size, AVPacket *avpkt)
442 const uint8_t *buf = avpkt->data;
443 int buf_size = avpkt->size;
444 LagarithContext *l = avctx->priv_data;
445 AVFrame *const p = &l->picture;
446 uint8_t frametype = 0;
447 uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
449 uint8_t *srcs[4], *dst;
450 int i, j, planes = 3;
452 AVFrame *picture = data;
455 avctx->release_buffer(avctx, p);
462 offset_gu = AV_RL32(buf + 1);
463 offset_bv = AV_RL32(buf + 5);
466 case FRAME_SOLID_RGBA:
467 avctx->pix_fmt = PIX_FMT_RGB32;
469 if (avctx->get_buffer(avctx, p) < 0) {
470 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
475 for (j = 0; j < avctx->height; j++) {
476 for (i = 0; i < avctx->width; i++)
477 AV_WN32(dst + i * 4, offset_gu);
478 dst += p->linesize[0];
481 case FRAME_ARITH_RGBA:
482 avctx->pix_fmt = PIX_FMT_RGB32;
485 offs[3] = AV_RL32(buf + 9);
486 case FRAME_ARITH_RGB24:
487 if (frametype == FRAME_ARITH_RGB24)
488 avctx->pix_fmt = PIX_FMT_RGB24;
490 if (avctx->get_buffer(avctx, p) < 0) {
491 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
499 if (!l->rgb_planes) {
500 l->rgb_stride = FFALIGN(avctx->width, 16);
501 l->rgb_planes = av_malloc(l->rgb_stride * avctx->height * planes);
502 if (!l->rgb_planes) {
503 av_log(avctx, AV_LOG_ERROR, "cannot allocate temporary buffer\n");
504 return AVERROR(ENOMEM);
507 for (i = 0; i < planes; i++)
508 srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;
509 for (i = 0; i < planes; i++)
510 lag_decode_arith_plane(l, srcs[i],
511 avctx->width, avctx->height,
512 -l->rgb_stride, buf + offs[i],
515 for (i = 0; i < planes; i++)
516 srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;
517 for (j = 0; j < avctx->height; j++) {
518 for (i = 0; i < avctx->width; i++) {
525 if (frametype == FRAME_ARITH_RGBA) {
527 AV_WN32(dst + i * 4, MKBETAG(a, r, g, b));
534 dst += p->linesize[0];
535 for (i = 0; i < planes; i++)
536 srcs[i] += l->rgb_stride;
539 case FRAME_ARITH_YV12:
540 avctx->pix_fmt = PIX_FMT_YUV420P;
542 if (avctx->get_buffer(avctx, p) < 0) {
543 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
547 lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
548 p->linesize[0], buf + offset_ry,
550 lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
551 avctx->height / 2, p->linesize[2],
552 buf + offset_gu, buf_size);
553 lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
554 avctx->height / 2, p->linesize[1],
555 buf + offset_bv, buf_size);
558 av_log(avctx, AV_LOG_ERROR,
559 "Unsupported Lagarith frame type: %#x\n", frametype);
564 *data_size = sizeof(AVFrame);
569 static av_cold int lag_decode_init(AVCodecContext *avctx)
571 LagarithContext *l = avctx->priv_data;
574 ff_dsputil_init(&l->dsp, avctx);
579 static av_cold int lag_decode_end(AVCodecContext *avctx)
581 LagarithContext *l = avctx->priv_data;
583 if (l->picture.data[0])
584 avctx->release_buffer(avctx, &l->picture);
585 av_freep(&l->rgb_planes);
590 AVCodec ff_lagarith_decoder = {
592 .type = AVMEDIA_TYPE_VIDEO,
593 .id = CODEC_ID_LAGARITH,
594 .priv_data_size = sizeof(LagarithContext),
595 .init = lag_decode_init,
596 .close = lag_decode_end,
597 .decode = lag_decode_frame,
598 .capabilities = CODEC_CAP_DR1,
599 .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),