FFmpeg: libavcodec/flvdec.c Source File

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libavcodec

flvdec.c

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1 /*

2 * FLV decoding.

3 * This file is part of FFmpeg.

4 *

5 * FFmpeg is free software; you can redistribute it and/or

6 * modify it under the terms of the GNU Lesser General Public

7 * License as published by the Free Software Foundation; either

8 * version 2.1 of the License, or (at your option) any later version.

9 *

10 * FFmpeg is distributed in the hope that it will be useful,

11 * but WITHOUT ANY WARRANTY; without even the implied warranty of

12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

13 * Lesser General Public License for more details.

14 *

15 * You should have received a copy of the GNU Lesser General Public

16 * License along with FFmpeg; if not, write to the Free Software

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

18 */

20 #include "mpegvideo.h"

21 #include "h263.h"

22 #include "flv.h"

23 #include "libavutil/imgutils.h"

25 void ff_flv2_decode_ac_esc(GetBitContext *gb, int *level, int *run, int *last)

26 {

27 int is11 = get_bits1(gb);

28 *last = get_bits1(gb);

29 *run = get_bits(gb, 6);

30 if (is11) {

31 *level = get_sbits(gb, 11);

32 } else {

33 *level = get_sbits(gb, 7);

34 }

35 }

37 int ff_flv_decode_picture_header(MpegEncContext *s)

38 {

39 int format, width, height;

41 /* picture header */

42 if (get_bits_long(&s->gb, 17) != 1) {

43 av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");

44 return AVERROR_INVALIDDATA;

45 }

46 format = get_bits(&s->gb, 5);

47 if (format != 0 && format != 1) {

48 av_log(s->avctx, AV_LOG_ERROR, "Bad picture format\n");

49 return AVERROR_INVALIDDATA;

50 }

51 s->h263_flv = format + 1;

52 s->picture_number = get_bits(&s->gb, 8); /* picture timestamp */

53 format = get_bits(&s->gb, 3);

54 switch (format) {

55 case 0:

56 width = get_bits(&s->gb, 8);

57 height = get_bits(&s->gb, 8);

58 break;

59 case 1:

60 width = get_bits(&s->gb, 16);

61 height = get_bits(&s->gb, 16);

62 break;

63 case 2:

64 width = 352;

65 height = 288;

66 break;

67 case 3:

68 width = 176;

69 height = 144;

70 break;

71 case 4:

72 width = 128;

73 height = 96;

74 break;

75 case 5:

76 width = 320;

77 height = 240;

78 break;

79 case 6:

80 width = 160;

81 height = 120;

82 break;

83 default:

84 width = height = 0;

85 break;

86 }

87 if (av_image_check_size(width, height, 0, s->avctx))

88 return AVERROR(EINVAL);

89 s->width = width;

90 s->height = height;

92 s->pict_type = AV_PICTURE_TYPE_I + get_bits(&s->gb, 2);

93 s->droppable = s->pict_type > AV_PICTURE_TYPE_P;

94 if (s->droppable)

95 s->pict_type = AV_PICTURE_TYPE_P;

97 skip_bits1(&s->gb); /* deblocking flag */

98 s->chroma_qscale = s->qscale = get_bits(&s->gb, 5);

100 s->h263_plus = 0;

101

102 s->unrestricted_mv = 1;

103 s->h263_long_vectors = 0;

104

105 /* PEI */

106 if (skip_1stop_8data_bits(&s->gb) < 0)

107 return AVERROR_INVALIDDATA;

108

109 s->f_code = 1;

110

111 if (s->ehc_mode)

112 s->avctx->sample_aspect_ratio= (AVRational){1,2};

113

114 if (s->avctx->debug & FF_DEBUG_PICT_INFO) {

115 av_log(s->avctx, AV_LOG_DEBUG, "%c esc_type:%d, qp:%d num:%d\n",

116 s->droppable ? 'D' : av_get_picture_type_char(s->pict_type),

117 s->h263_flv - 1, s->qscale, s->picture_number);

118 }

119

120 s->y_dc_scale_table = s->c_dc_scale_table = ff_mpeg1_dc_scale_table;

121

122 return 0;

123 }

124

125 AVCodec ff_flv_decoder = {

126 .name = "flv",

127 .long_name = NULL_IF_CONFIG_SMALL("FLV / Sorenson Spark / Sorenson H.263 (Flash Video)"),

128 .type = AVMEDIA_TYPE_VIDEO,

129 .id = AV_CODEC_ID_FLV1,

130 .priv_data_size = sizeof(MpegEncContext),

131 .init = ff_h263_decode_init,

132 .close = ff_h263_decode_end,

133 .decode = ff_h263_decode_frame,

134 .capabilities = CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1,

135 .max_lowres = 3,

136 .pix_fmts = (const enum AVPixelFormat[]) {

137 AV_PIX_FMT_YUV420P,

138 AV_PIX_FMT_NONE

139 },

140 };

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