FFmpeg: libavcodec/wnv1.c Source File

FFmpeg

[フレーム]

libavcodec

wnv1.c

Go to the documentation of this file.

1 /*

2 * Winnov WNV1 codec

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 * Winnov WNV1 codec.

25 */

27 #include "avcodec.h"

28 #include "get_bits.h"

29 #include "internal.h"

30 #include "mathops.h"

33 typedef struct WNV1Context {

34 int shift;

35 GetBitContext gb;

36 } WNV1Context;

38 static const uint16_t code_tab[16][2] = {

39 { 0x1FD, 9 }, { 0xFD, 8 }, { 0x7D, 7 }, { 0x3D, 6 }, { 0x1D, 5 }, { 0x0D, 4 }, { 0x005, 3 },

40 { 0x000, 1 },

41 { 0x004, 3 }, { 0x0C, 4 }, { 0x1C, 5 }, { 0x3C, 6 }, { 0x7C, 7 }, { 0xFC, 8 }, { 0x1FC, 9 }, { 0xFF, 8 }

42 };

44 #define CODE_VLC_BITS 9

45 static VLC code_vlc;

47 /* returns modified base_value */

48 static inline int wnv1_get_code(WNV1Context *w, int base_value)

49 {

50 int v = get_vlc2(&w->gb, code_vlc.table, CODE_VLC_BITS, 1);

52 if (v == 15)

53 return ff_reverse[get_bits(&w->gb, 8 - w->shift)];

54 else

55 return base_value + ((v - 7) << w->shift);

56 }

58 static int decode_frame(AVCodecContext *avctx,

59 void *data, int *got_frame,

60 AVPacket *avpkt)

61 {

62 WNV1Context * const l = avctx->priv_data;

63 const uint8_t *buf = avpkt->data;

64 int buf_size = avpkt->size;

65 AVFrame * const p = data;

66 unsigned char *Y,*U,*V;

67 int i, j, ret;

68 int prev_y = 0, prev_u = 0, prev_v = 0;

69 uint8_t *rbuf;

71 if (buf_size <= 8) {

72 av_log(avctx, AV_LOG_ERROR, "Packet size %d is too small\n", buf_size);

73 return AVERROR_INVALIDDATA;

74 }

76 rbuf = av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);

77 if (!rbuf) {

78 av_log(avctx, AV_LOG_ERROR, "Cannot allocate temporary buffer\n");

79 return AVERROR(ENOMEM);

80 }

82 if ((ret = ff_get_buffer(avctx, p, 0)) < 0) {

83 av_free(rbuf);

84 return ret;

85 }

86 p->key_frame = 1;

88 for (i = 8; i < buf_size; i++)

89 rbuf[i] = ff_reverse[buf[i]];

90 init_get_bits(&l->gb, rbuf + 8, (buf_size - 8) * 8);

92 if (buf[2] >> 4 == 6)

93 l->shift = 2;

94 else {

95 l->shift = 8 - (buf[2] >> 4);

96 if (l->shift > 4) {

97 avpriv_request_sample(avctx,

98 "Unknown WNV1 frame header value %i",

99 buf[2] >> 4);

100 l->shift = 4;

101 }

102 if (l->shift < 1) {

103 avpriv_request_sample(avctx,

104 "Unknown WNV1 frame header value %i",

105 buf[2] >> 4);

106 l->shift = 1;

107 }

108 }

109

110 Y = p->data[0];

111 U = p->data[1];

112 V = p->data[2];

113 for (j = 0; j < avctx->height; j++) {

114 for (i = 0; i < avctx->width / 2; i++) {

115 Y[i * 2] = wnv1_get_code(l, prev_y);

116 prev_u = U[i] = wnv1_get_code(l, prev_u);

117 prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);

118 prev_v = V[i] = wnv1_get_code(l, prev_v);

119 }

120 Y += p->linesize[0];

121 U += p->linesize[1];

122 V += p->linesize[2];

123 }

124

125

126 *got_frame = 1;

127 av_free(rbuf);

128

129 return buf_size;

130 }

131

132 static av_cold int decode_init(AVCodecContext *avctx)

133 {

134 static VLC_TYPE code_table[1 << CODE_VLC_BITS][2];

135

136 avctx->pix_fmt = AV_PIX_FMT_YUV422P;

137

138 code_vlc.table = code_table;

139 code_vlc.table_allocated = 1 << CODE_VLC_BITS;

140 init_vlc(&code_vlc, CODE_VLC_BITS, 16,

141 &code_tab[0][1], 4, 2,

142 &code_tab[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);

143

144 return 0;

145 }

146

147 AVCodec ff_wnv1_decoder = {

148 .name = "wnv1",

149 .long_name = NULL_IF_CONFIG_SMALL("Winnov WNV1"),

150 .type = AVMEDIA_TYPE_VIDEO,

151 .id = AV_CODEC_ID_WNV1,

152 .priv_data_size = sizeof(WNV1Context),

153 .init = decode_init,

154 .decode = decode_frame,

155 .capabilities = CODEC_CAP_DR1,

156 };

Generated on Sat Jan 25 2014 19:51:58 for FFmpeg by doxygen 1.8.2