FFmpeg: libavcodec/aliaspixdec.c Source File

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libavcodec

aliaspixdec.c

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1 /*

2 * Alias PIX image decoder

4 *

5 * This file is part of FFmpeg.

6 *

7 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software

19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

20 */

22 #include "libavutil/intreadwrite.h"

24 #include "avcodec.h"

25 #include "bytestream.h"

26 #include "internal.h"

28 #define ALIAS_HEADER_SIZE 10

30 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

31 AVPacket *avpkt)

32 {

33 AVFrame *f = data;

34 GetByteContext gb;

35 int width, height, ret, bits_pixel, pixel;

36 uint8_t *out_buf;

37 uint8_t count;

38 int x, y;

40 bytestream2_init(&gb, avpkt->data, avpkt->size);

42 if (bytestream2_get_bytes_left(&gb) < ALIAS_HEADER_SIZE) {

43 av_log(avctx, AV_LOG_ERROR, "Header too small %d.\n", avpkt->size);

44 return AVERROR_INVALIDDATA;

45 }

47 width = bytestream2_get_be16u(&gb);

48 height = bytestream2_get_be16u(&gb);

49 bytestream2_skipu(&gb, 4); // obsolete X, Y offset

50 bits_pixel = bytestream2_get_be16u(&gb);

52 if (bits_pixel == 24)

53 avctx->pix_fmt = AV_PIX_FMT_BGR24;

54 else if (bits_pixel == 8)

55 avctx->pix_fmt = AV_PIX_FMT_GRAY8;

56 else {

57 av_log(avctx, AV_LOG_ERROR, "Invalid pixel format.\n");

58 return AVERROR_INVALIDDATA;

59 }

61 ret = ff_set_dimensions(avctx, width, height);

62 if (ret < 0)

63 return ret;

65 ret = ff_get_buffer(avctx, f, 0);

66 if (ret < 0)

67 return ret;

69 f->pict_type = AV_PICTURE_TYPE_I;

70 f->key_frame = 1;

72 x = 0;

73 y = 1;

74 out_buf = f->data[0];

75 while (bytestream2_get_bytes_left(&gb) > 0) {

76 int i;

78 /* set buffer at the right position at every new line */

79 if (x == avctx->width) {

80 x = 0;

81 out_buf = f->data[0] + f->linesize[0] * y++;

82 if (y > avctx->height) {

83 av_log(avctx, AV_LOG_ERROR,

84 "Ended frame decoding with %d bytes left.\n",

85 bytestream2_get_bytes_left(&gb));

86 return AVERROR_INVALIDDATA;

87 }

88 }

90 /* read packet and copy data */

91 count = bytestream2_get_byteu(&gb);

92 if (!count || x + count > avctx->width) {

93 av_log(avctx, AV_LOG_ERROR, "Invalid run length %d.\n", count);

94 return AVERROR_INVALIDDATA;

95 }

97 if (avctx->pix_fmt == AV_PIX_FMT_BGR24) {

98 pixel = bytestream2_get_be24(&gb);

99 for (i = 0; i < count; i++) {

100 AV_WB24(out_buf, pixel);

101 out_buf += 3;

102 }

103 } else { // AV_PIX_FMT_GRAY8

104 pixel = bytestream2_get_byte(&gb);

105 for (i = 0; i < count; i++)

106 *out_buf++ = pixel;

107 }

108

109 x += i;

110 }

111

112 if (x != width || y != height) {

113 av_log(avctx, AV_LOG_ERROR, "Picture stopped at %d,%d.\n", x, y);

114 return AVERROR_INVALIDDATA;

115 }

116

117 *got_frame = 1;

118 return avpkt->size;

119 }

120

121 AVCodec ff_alias_pix_decoder = {

122 .name = "alias_pix",

123 .long_name = NULL_IF_CONFIG_SMALL("Alias/Wavefront PIX image"),

124 .type = AVMEDIA_TYPE_VIDEO,

125 .id = AV_CODEC_ID_ALIAS_PIX,

126 .decode = decode_frame,

127 .capabilities = CODEC_CAP_DR1,

128 };

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