vble.c
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1 /*
2  * VBLE Decoder
3  * Copyright (c) 2011 Derek Buitenhuis
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
27 #define BITSTREAM_READER_LE
28 
29 #include "avcodec.h"
30 #include "dsputil.h"
31 #include "get_bits.h"
32 
33 typedef struct {
36 
37  int size;
38  uint8_t *val; /* First holds the lengths of vlc symbols and then their values */
39 } VBLEContext;
40 
42 {
43  /* At most we need to read 9 bits total to get indices up to 8 */
44  uint8_t val = show_bits(gb, 8);
45 
46  if (val) {
47  val = 7 - av_log2_16bit(av_reverse[val]);
48  skip_bits(gb, val + 1);
49  return val;
50  } else {
51  skip_bits(gb, 8);
52  if (get_bits1(gb))
53  return 8;
54  }
55 
56  /* Return something larger than 8 on error */
57  return UINT8_MAX;
58 }
59 
60 static int vble_unpack(VBLEContext *ctx, GetBitContext *gb)
61 {
62  int i;
63 
64  /* Read all the lengths in first */
65  for (i = 0; i < ctx->size; i++) {
66  ctx->val[i] = vble_read_reverse_unary(gb);
67 
68  if (ctx->val[i] == UINT8_MAX)
69  return -1;
70  }
71 
72  for (i = 0; i < ctx->size; i++) {
73  /* Check we have enough bits left */
74  if (get_bits_left(gb) < ctx->val[i])
75  return -1;
76 
77  /* get_bits can't take a length of 0 */
78  if (ctx->val[i])
79  ctx->val[i] = (1 << ctx->val[i]) + get_bits(gb, ctx->val[i]) - 1;
80  }
81 
82  return 0;
83 }
84 
85 static void vble_restore_plane(VBLEContext *ctx, int plane, int offset,
86  int width, int height)
87 {
88  AVFrame *pic = ctx->avctx->coded_frame;
89  uint8_t *dst = pic->data[plane];
90  uint8_t *val = ctx->val + offset;
91  int stride = pic->linesize[plane];
92  int i, j, left, left_top;
93 
94  for (i = 0; i < height; i++) {
95  for (j = 0; j < width; j++)
96  val[j] = (val[j] >> 1) ^ -(val[j] & 1);
97 
98  if (i) {
99  left = 0;
100  left_top = dst[-stride];
101  ctx->dsp.add_hfyu_median_prediction(dst, dst-stride, val,
102  width, &left, &left_top);
103  } else {
104  dst[0] = val[0];
105  for (j = 1; j < width; j++)
106  dst[j] = val[j] + dst[j - 1];
107  }
108  dst += stride;
109  val += width;
110  }
111 }
112 
113 static int vble_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
114  AVPacket *avpkt)
115 {
116  VBLEContext *ctx = avctx->priv_data;
117  AVFrame *pic = avctx->coded_frame;
118  GetBitContext gb;
119  const uint8_t *src = avpkt->data;
120  int version;
121  int offset = 0;
122  int width_uv = avctx->width / 2, height_uv = avctx->height / 2;
123 
124  pic->reference = 0;
125 
126  /* Clear buffer if need be */
127  if (pic->data[0])
128  avctx->release_buffer(avctx, pic);
129 
130  /* Allocate buffer */
131  if (avctx->get_buffer(avctx, pic) < 0) {
132  av_log(avctx, AV_LOG_ERROR, "Could not allocate buffer.\n");
133  return AVERROR(ENOMEM);
134  }
135 
136  /* Set flags */
137  pic->key_frame = 1;
139 
140  /* Version should always be 1 */
141  version = AV_RL32(src);
142 
143  if (version != 1) {
144  av_log(avctx, AV_LOG_ERROR, "Unsupported VBLE Version: %d\n", version);
145  return AVERROR_INVALIDDATA;
146  }
147 
148  init_get_bits(&gb, src + 4, (avpkt->size - 4) * 8);
149 
150  /* Unpack */
151  if (vble_unpack(ctx, &gb) < 0) {
152  av_log(avctx, AV_LOG_ERROR, "Invalid Code\n");
153  return AVERROR_INVALIDDATA;
154  }
155 
156  /* Restore planes. Should be almost identical to Huffyuv's. */
157  vble_restore_plane(ctx, 0, offset, avctx->width, avctx->height);
158 
159  /* Chroma */
160  if (!(ctx->avctx->flags & CODEC_FLAG_GRAY)) {
161  offset += avctx->width * avctx->height;
162  vble_restore_plane(ctx, 1, offset, width_uv, height_uv);
163 
164  offset += width_uv * height_uv;
165  vble_restore_plane(ctx, 2, offset, width_uv, height_uv);
166  }
167 
168  *data_size = sizeof(AVFrame);
169  *(AVFrame *)data = *pic;
170 
171  return avpkt->size;
172 }
173 
175 {
176  VBLEContext *ctx = avctx->priv_data;
177  AVFrame *pic = avctx->coded_frame;
178 
179  if (pic->data[0])
180  avctx->release_buffer(avctx, pic);
181 
182  av_freep(&avctx->coded_frame);
183  av_freep(&ctx->val);
184 
185  return 0;
186 }
187 
189 {
190  VBLEContext *ctx = avctx->priv_data;
191 
192  /* Stash for later use */
193  ctx->avctx = avctx;
194  dsputil_init(&ctx->dsp, avctx);
195 
196  avctx->pix_fmt = PIX_FMT_YUV420P;
197  avctx->bits_per_raw_sample = 8;
198  avctx->coded_frame = avcodec_alloc_frame();
199 
200  if (!avctx->coded_frame) {
201  av_log(avctx, AV_LOG_ERROR, "Could not allocate frame.\n");
202  return AVERROR(ENOMEM);
203  }
204 
205  ctx->size = avpicture_get_size(avctx->pix_fmt,
206  avctx->width, avctx->height);
207 
208  ctx->val = av_malloc(ctx->size * sizeof(*ctx->val));
209 
210  if (!ctx->val) {
211  av_log(avctx, AV_LOG_ERROR, "Could not allocate values buffer.\n");
212  vble_decode_close(avctx);
213  return AVERROR(ENOMEM);
214  }
215 
216  return 0;
217 }
218 
220  .name = "vble",
221  .type = AVMEDIA_TYPE_VIDEO,
222  .id = CODEC_ID_VBLE,
223  .priv_data_size = sizeof(VBLEContext),
227  .capabilities = CODEC_CAP_DR1,
228  .long_name = NULL_IF_CONFIG_SMALL("VBLE Lossless Codec"),
229 };