FFmpeg: libavcodec/bethsoftvideo.c Source File

FFmpeg

[フレーム]

libavcodec

bethsoftvideo.c

Go to the documentation of this file.

1 /*

2 * Bethesda VID video 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 /**

23 * @file

24 * @brief Bethesda Softworks VID Video Decoder

25 * @author Nicholas Tung [ntung (at. ntung com] (2007-03)

26 * @see http://wiki.multimedia.cx/index.php?title=Bethsoft_VID

27 * @see http://www.svatopluk.com/andux/docs/dfvid.html

28 */

30 #include "libavutil/common.h"

31 #include "avcodec.h"

32 #include "bethsoftvideo.h"

33 #include "bytestream.h"

34 #include "internal.h"

36 typedef struct BethsoftvidContext {

37 AVFrame frame;

38 GetByteContext g;

39 } BethsoftvidContext;

41 static av_cold int bethsoftvid_decode_init(AVCodecContext *avctx)

42 {

43 BethsoftvidContext *vid = avctx->priv_data;

44 avcodec_get_frame_defaults(&vid->frame);

45 avctx->pix_fmt = AV_PIX_FMT_PAL8;

46 return 0;

47 }

49 static int set_palette(BethsoftvidContext *ctx)

50 {

51 uint32_t *palette = (uint32_t *)ctx->frame.data[1];

52 int a;

54 if (bytestream2_get_bytes_left(&ctx->g) < 256*3)

55 return AVERROR_INVALIDDATA;

57 for(a = 0; a < 256; a++){

58 palette[a] = 0xFFU << 24 | bytestream2_get_be24u(&ctx->g) * 4;

59 palette[a] |= palette[a] >> 6 & 0x30303;

60 }

61 ctx->frame.palette_has_changed = 1;

62 return 0;

63 }

65 static int bethsoftvid_decode_frame(AVCodecContext *avctx,

66 void *data, int *got_frame,

67 AVPacket *avpkt)

68 {

69 BethsoftvidContext * vid = avctx->priv_data;

70 char block_type;

71 uint8_t * dst;

72 uint8_t * frame_end;

73 int remaining = avctx->width; // number of bytes remaining on a line

74 int wrap_to_next_line;

75 int code, ret;

76 int yoffset;

78 if ((ret = ff_reget_buffer(avctx, &vid->frame)) < 0)

79 return ret;

80 wrap_to_next_line = vid->frame.linesize[0] - avctx->width;

82 if (avpkt->side_data_elems > 0 &&

83 avpkt->side_data[0].type == AV_PKT_DATA_PALETTE) {

84 bytestream2_init(&vid->g, avpkt->side_data[0].data,

85 avpkt->side_data[0].size);

86 if ((ret = set_palette(vid)) < 0)

87 return ret;

88 }

90 bytestream2_init(&vid->g, avpkt->data, avpkt->size);

91 dst = vid->frame.data[0];

92 frame_end = vid->frame.data[0] + vid->frame.linesize[0] * avctx->height;

94 switch(block_type = bytestream2_get_byte(&vid->g)){

95 case PALETTE_BLOCK: {

96 *got_frame = 0;

97 if ((ret = set_palette(vid)) < 0) {

98 av_log(avctx, AV_LOG_ERROR, "error reading palette\n");

99 return ret;

100 }

101 return bytestream2_tell(&vid->g);

102 }

103 case VIDEO_YOFF_P_FRAME:

104 yoffset = bytestream2_get_le16(&vid->g);

105 if(yoffset >= avctx->height)

106 return AVERROR_INVALIDDATA;

107 dst += vid->frame.linesize[0] * yoffset;

108 }

109

110 // main code

111 while((code = bytestream2_get_byte(&vid->g))){

112 int length = code & 0x7f;

113

114 // copy any bytes starting at the current position, and ending at the frame width

115 while(length > remaining){

116 if(code < 0x80)

117 bytestream2_get_buffer(&vid->g, dst, remaining);

118 else if(block_type == VIDEO_I_FRAME)

119 memset(dst, bytestream2_peek_byte(&vid->g), remaining);

120 length -= remaining; // decrement the number of bytes to be copied

121 dst += remaining + wrap_to_next_line; // skip over extra bytes at end of frame

122 remaining = avctx->width;

123 if(dst == frame_end)

124 goto end;

125 }

126

127 // copy any remaining bytes after / if line overflows

128 if(code < 0x80)

129 bytestream2_get_buffer(&vid->g, dst, length);

130 else if(block_type == VIDEO_I_FRAME)

131 memset(dst, bytestream2_get_byte(&vid->g), length);

132 remaining -= length;

133 dst += length;

134 }

135 end:

136

137 if ((ret = av_frame_ref(data, &vid->frame)) < 0)

138 return ret;

139

140 *got_frame = 1;

141

142 return avpkt->size;

143 }

144

145 static av_cold int bethsoftvid_decode_end(AVCodecContext *avctx)

146 {

147 BethsoftvidContext * vid = avctx->priv_data;

148 av_frame_unref(&vid->frame);

149 return 0;

150 }

151

152 AVCodec ff_bethsoftvid_decoder = {

153 .name = "bethsoftvid",

154 .type = AVMEDIA_TYPE_VIDEO,

155 .id = AV_CODEC_ID_BETHSOFTVID,

156 .priv_data_size = sizeof(BethsoftvidContext),

157 .init = bethsoftvid_decode_init,

158 .close = bethsoftvid_decode_end,

159 .decode = bethsoftvid_decode_frame,

160 .capabilities = CODEC_CAP_DR1,

161 .long_name = NULL_IF_CONFIG_SMALL("Bethesda VID video"),

162 };

Generated on Wed Jul 10 2013 23:47:56 for FFmpeg by doxygen 1.8.2