FFmpeg: libavcodec/bethsoftvideo.c Source File

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libavcodec

bethsoftvideo.c

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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 avctx->pix_fmt = AV_PIX_FMT_PAL8;

46 vid->frame = av_frame_alloc();

47 if (!vid->frame)

48 return AVERROR(ENOMEM);

50 return 0;

51 }

53 static int set_palette(BethsoftvidContext *ctx)

54 {

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

56 int a;

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

59 return AVERROR_INVALIDDATA;

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

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

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

64 }

65 ctx->frame->palette_has_changed = 1;

66 return 0;

67 }

69 static int bethsoftvid_decode_frame(AVCodecContext *avctx,

70 void *data, int *got_frame,

71 AVPacket *avpkt)

72 {

73 BethsoftvidContext * vid = avctx->priv_data;

74 char block_type;

75 uint8_t * dst;

76 uint8_t * frame_end;

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

78 int wrap_to_next_line;

79 int code, ret;

80 int yoffset;

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

83 return ret;

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

86 if (avpkt->side_data_elems > 0 &&

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

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

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

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

91 return ret;

92 }

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

95 dst = vid->frame->data[0];

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

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

99 case PALETTE_BLOCK: {

100 *got_frame = 0;

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

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

103 return ret;

104 }

105 return bytestream2_tell(&vid->g);

106 }

107 case VIDEO_YOFF_P_FRAME:

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

109 if(yoffset >= avctx->height)

110 return AVERROR_INVALIDDATA;

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

112 }

113

114 // main code

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

116 int length = code & 0x7f;

117

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

119 while(length > remaining){

120 if(code < 0x80)

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

122 else if(block_type == VIDEO_I_FRAME)

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

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

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

126 remaining = avctx->width;

127 if(dst == frame_end)

128 goto end;

129 }

130

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

132 if(code < 0x80)

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

134 else if(block_type == VIDEO_I_FRAME)

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

136 remaining -= length;

137 dst += length;

138 }

139 end:

140

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

142 return ret;

143

144 *got_frame = 1;

145

146 return avpkt->size;

147 }

148

149 static av_cold int bethsoftvid_decode_end(AVCodecContext *avctx)

150 {

151 BethsoftvidContext * vid = avctx->priv_data;

152 av_frame_free(&vid->frame);

153 return 0;

154 }

155

156 AVCodec ff_bethsoftvid_decoder = {

157 .name = "bethsoftvid",

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

159 .type = AVMEDIA_TYPE_VIDEO,

160 .id = AV_CODEC_ID_BETHSOFTVID,

161 .priv_data_size = sizeof(BethsoftvidContext),

162 .init = bethsoftvid_decode_init,

163 .close = bethsoftvid_decode_end,

164 .decode = bethsoftvid_decode_frame,

165 .capabilities = CODEC_CAP_DR1,

166 };

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