Libav
bmpenc.c
Go to the documentation of this file.
1 /*
2  * BMP image format encoder
3  * Copyright (c) 2006, 2007 Michel Bardiaux
4  * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
5  *
6  * This file is part of Libav.
7  *
8  * Libav is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * Libav is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "libavutil/imgutils.h"
24 #include "avcodec.h"
25 #include "bytestream.h"
26 #include "bmp.h"
27 #include "internal.h"
28 
29 static const uint32_t monoblack_pal[] = { 0x000000, 0xFFFFFF };
30 static const uint32_t rgb565_masks[] = { 0xF800, 0x07E0, 0x001F };
31 static const uint32_t rgb444_masks[] = { 0x0F00, 0x00F0, 0x000F };
32 
34  switch (avctx->pix_fmt) {
35  case AV_PIX_FMT_BGR24:
36  avctx->bits_per_coded_sample = 24;
37  break;
38  case AV_PIX_FMT_RGB555:
39  case AV_PIX_FMT_RGB565:
40  case AV_PIX_FMT_RGB444:
41  avctx->bits_per_coded_sample = 16;
42  break;
43  case AV_PIX_FMT_RGB8:
44  case AV_PIX_FMT_BGR8:
47  case AV_PIX_FMT_GRAY8:
48  case AV_PIX_FMT_PAL8:
49  avctx->bits_per_coded_sample = 8;
50  break;
52  avctx->bits_per_coded_sample = 1;
53  break;
54  default:
55  av_log(avctx, AV_LOG_INFO, "unsupported pixel format\n");
56  return -1;
57  }
58 
59  avctx->coded_frame = av_frame_alloc();
60  if (!avctx->coded_frame)
61  return AVERROR(ENOMEM);
62 
63  return 0;
64 }
65 
66 static int bmp_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
67  const AVFrame *pict, int *got_packet)
68 {
69  const AVFrame * const p = pict;
70  int n_bytes_image, n_bytes_per_row, n_bytes, i, n, hsize, ret;
71  const uint32_t *pal = NULL;
72  int pad_bytes_per_row, pal_entries = 0, compression = BMP_RGB;
73  int bit_count = avctx->bits_per_coded_sample;
74  uint8_t *ptr, *buf;
75 
77  avctx->coded_frame->key_frame = 1;
78  switch (avctx->pix_fmt) {
79  case AV_PIX_FMT_RGB444:
80  compression = BMP_BITFIELDS;
81  pal = rgb444_masks; // abuse pal to hold color masks
82  pal_entries = 3;
83  break;
84  case AV_PIX_FMT_RGB565:
85  compression = BMP_BITFIELDS;
86  pal = rgb565_masks; // abuse pal to hold color masks
87  pal_entries = 3;
88  break;
89  case AV_PIX_FMT_RGB8:
90  case AV_PIX_FMT_BGR8:
93  case AV_PIX_FMT_GRAY8:
94  avpriv_set_systematic_pal2((uint32_t*)p->data[1], avctx->pix_fmt);
95  case AV_PIX_FMT_PAL8:
96  pal = (uint32_t *)p->data[1];
97  break;
99  pal = monoblack_pal;
100  break;
101  }
102  if (pal && !pal_entries) pal_entries = 1 << bit_count;
103  n_bytes_per_row = ((int64_t)avctx->width * (int64_t)bit_count + 7LL) >> 3LL;
104  pad_bytes_per_row = (4 - n_bytes_per_row) & 3;
105  n_bytes_image = avctx->height * (n_bytes_per_row + pad_bytes_per_row);
106 
107  // STRUCTURE.field refer to the MSVC documentation for BITMAPFILEHEADER
108  // and related pages.
109 #define SIZE_BITMAPFILEHEADER 14
110 #define SIZE_BITMAPINFOHEADER 40
111  hsize = SIZE_BITMAPFILEHEADER + SIZE_BITMAPINFOHEADER + (pal_entries << 2);
112  n_bytes = n_bytes_image + hsize;
113  if ((ret = ff_alloc_packet(pkt, n_bytes)) < 0) {
114  av_log(avctx, AV_LOG_ERROR, "Error getting output packet.\n");
115  return ret;
116  }
117  buf = pkt->data;
118  bytestream_put_byte(&buf, 'B'); // BITMAPFILEHEADER.bfType
119  bytestream_put_byte(&buf, 'M'); // do.
120  bytestream_put_le32(&buf, n_bytes); // BITMAPFILEHEADER.bfSize
121  bytestream_put_le16(&buf, 0); // BITMAPFILEHEADER.bfReserved1
122  bytestream_put_le16(&buf, 0); // BITMAPFILEHEADER.bfReserved2
123  bytestream_put_le32(&buf, hsize); // BITMAPFILEHEADER.bfOffBits
124  bytestream_put_le32(&buf, SIZE_BITMAPINFOHEADER); // BITMAPINFOHEADER.biSize
125  bytestream_put_le32(&buf, avctx->width); // BITMAPINFOHEADER.biWidth
126  bytestream_put_le32(&buf, avctx->height); // BITMAPINFOHEADER.biHeight
127  bytestream_put_le16(&buf, 1); // BITMAPINFOHEADER.biPlanes
128  bytestream_put_le16(&buf, bit_count); // BITMAPINFOHEADER.biBitCount
129  bytestream_put_le32(&buf, compression); // BITMAPINFOHEADER.biCompression
130  bytestream_put_le32(&buf, n_bytes_image); // BITMAPINFOHEADER.biSizeImage
131  bytestream_put_le32(&buf, 0); // BITMAPINFOHEADER.biXPelsPerMeter
132  bytestream_put_le32(&buf, 0); // BITMAPINFOHEADER.biYPelsPerMeter
133  bytestream_put_le32(&buf, 0); // BITMAPINFOHEADER.biClrUsed
134  bytestream_put_le32(&buf, 0); // BITMAPINFOHEADER.biClrImportant
135  for (i = 0; i < pal_entries; i++)
136  bytestream_put_le32(&buf, pal[i] & 0xFFFFFF);
137  // BMP files are bottom-to-top so we start from the end...
138  ptr = p->data[0] + (avctx->height - 1) * p->linesize[0];
139  buf = pkt->data + hsize;
140  for(i = 0; i < avctx->height; i++) {
141  if (bit_count == 16) {
142  const uint16_t *src = (const uint16_t *) ptr;
143  uint16_t *dst = (uint16_t *) buf;
144  for(n = 0; n < avctx->width; n++)
145  AV_WL16(dst + n, src[n]);
146  } else {
147  memcpy(buf, ptr, n_bytes_per_row);
148  }
149  buf += n_bytes_per_row;
150  memset(buf, 0, pad_bytes_per_row);
151  buf += pad_bytes_per_row;
152  ptr -= p->linesize[0]; // ... and go back
153  }
154 
155  pkt->flags |= AV_PKT_FLAG_KEY;
156  *got_packet = 1;
157  return 0;
158 }
159 
161 {
162  av_frame_free(&avctx->coded_frame);
163  return 0;
164 }
165 
167  .name = "bmp",
168  .long_name = NULL_IF_CONFIG_SMALL("BMP (Windows and OS/2 bitmap)"),
169  .type = AVMEDIA_TYPE_VIDEO,
170  .id = AV_CODEC_ID_BMP,
171  .init = bmp_encode_init,
172  .encode2 = bmp_encode_frame,
173  .close = bmp_encode_close,
174  .pix_fmts = (const enum AVPixelFormat[]){
180  },
181 };