FFmpeg: libavcodec/flvdec.c Source File

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libavcodec

flvdec.c

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1 /*

2 * FLV decoding.

3 *

4 * This file is part of FFmpeg.

5 *

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

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

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

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

10 *

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

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

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

14 * Lesser General Public License for more details.

15 *

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

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

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

19 */

21 #include "libavutil/imgutils.h"

23 #include "codec_internal.h"

24 #include "flvdec.h"

25 #include "h263dec.h"

26 #include "mpegvideo.h"

27 #include "mpegvideodata.h"

29 int ff_flv_decode_picture_header(MpegEncContext *s)

30 {

31 int format, width, height;

33 /* picture header */

34 if (get_bits(&s->gb, 17) != 1) {

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

36 return AVERROR_INVALIDDATA;

37 }

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

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

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

41 return AVERROR_INVALIDDATA;

42 }

43 s->h263_flv = format + 1;

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

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

46 switch (format) {

47 case 0:

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

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

50 break;

51 case 1:

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

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

54 break;

55 case 2:

56 width = 352;

57 height = 288;

58 break;

59 case 3:

60 width = 176;

61 height = 144;

62 break;

63 case 4:

64 width = 128;

65 height = 96;

66 break;

67 case 5:

68 width = 320;

69 height = 240;

70 break;

71 case 6:

72 width = 160;

73 height = 120;

74 break;

75 default:

76 width = height = 0;

77 break;

78 }

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

80 return AVERROR(EINVAL);

81 s->width = width;

82 s->height = height;

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

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

86 if (s->droppable)

87 s->pict_type = AV_PICTURE_TYPE_P;

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

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

92 s->h263_plus = 0;

94 s->h263_long_vectors = 0;

96 /* PEI */

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

98 return AVERROR_INVALIDDATA;

100 s->f_code = 1;

101

102 if (s->ehc_mode)

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

104

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

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

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

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

109 }

110

111 return 0;

112 }

113

114 const FFCodec ff_flv_decoder = {

115 .p.name = "flv",

116 CODEC_LONG_NAME("FLV / Sorenson Spark / Sorenson H.263 (Flash Video)"),

117 .p.type = AVMEDIA_TYPE_VIDEO,

118 .p.id = AV_CODEC_ID_FLV1,

119 .priv_data_size = sizeof(MpegEncContext),

120 .init = ff_h263_decode_init,

121 .close = ff_h263_decode_end,

122 FF_CODEC_DECODE_CB(ff_h263_decode_frame),

123 .p.capabilities = AV_CODEC_CAP_DRAW_HORIZ_BAND | AV_CODEC_CAP_DR1,

124 .caps_internal = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM,

125 .p.max_lowres = 3,

126 .p.pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV420P,

127 AV_PIX_FMT_NONE },

128 };

AVPixelFormat

Pixel format.

Definition: pixfmt.h:64

AVERROR

Filter the word "frame" indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions

FFCodec

Definition: codec_internal.h:127

mpegvideo.h

ff_flv_decoder

const FFCodec ff_flv_decoder

Definition: flvdec.c:114

FF_DEBUG_PICT_INFO

#define FF_DEBUG_PICT_INFO

Definition: avcodec.h:1359

get_bits

static unsigned int get_bits(GetBitContext *s, int n)

Read 1-25 bits.