FFmpeg: libavformat/astdec.c Source File

FFmpeg

[フレーム]

libavformat

astdec.c

Go to the documentation of this file.

1 /*

2 * AST demuxer

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 #include "libavutil/channel_layout.h"

23 #include "libavutil/intreadwrite.h"

24 #include "avformat.h"

25 #include "internal.h"

26 #include "ast.h"

28 static int ast_probe(AVProbeData *p)

29 {

30 if (AV_RL32(p->buf) == MKTAG('S','T','R','M') &&

31 AV_RB16(p->buf + 10) &&

32 AV_RB16(p->buf + 12) &&

33 AV_RB32(p->buf + 16))

34 return AVPROBE_SCORE_MAX / 3 * 2;

35 return 0;

36 }

38 static int ast_read_header(AVFormatContext *s)

39 {

40 int depth;

41 AVStream *st;

43 st = avformat_new_stream(s, NULL);

44 if (!st)

45 return AVERROR(ENOMEM);

47 avio_skip(s->pb, 8);

48 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

49 st->codec->codec_id = ff_codec_get_id(ff_codec_ast_tags, avio_rb16(s->pb));

51 depth = avio_rb16(s->pb);

52 if (depth != 16) {

53 avpriv_request_sample(s, "depth %d", depth);

54 return AVERROR_INVALIDDATA;

55 }

57 st->codec->channels = avio_rb16(s->pb);

58 if (!st->codec->channels)

59 return AVERROR_INVALIDDATA;

61 if (st->codec->channels == 2)

62 st->codec->channel_layout = AV_CH_LAYOUT_STEREO;

63 else if (st->codec->channels == 4)

64 st->codec->channel_layout = AV_CH_LAYOUT_4POINT0;

66 avio_skip(s->pb, 2);

67 st->codec->sample_rate = avio_rb32(s->pb);

68 if (st->codec->sample_rate <= 0)

69 return AVERROR_INVALIDDATA;

70 st->start_time = 0;

71 st->duration = avio_rb32(s->pb);

72 avio_skip(s->pb, 40);

73 avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);

75 return 0;

76 }

78 static int ast_read_packet(AVFormatContext *s, AVPacket *pkt)

79 {

80 uint32_t type, size;

81 int64_t pos;

82 int ret;

84 if (url_feof(s->pb))

85 return AVERROR_EOF;

87 pos = avio_tell(s->pb);

88 type = avio_rl32(s->pb);

89 size = avio_rb32(s->pb);

90 if (size > INT_MAX / s->streams[0]->codec->channels)

91 return AVERROR_INVALIDDATA;

93 size *= s->streams[0]->codec->channels;

94 if ((ret = avio_skip(s->pb, 24)) < 0) // padding

95 return ret;

97 if (type == MKTAG('B','L','C','K')) {

98 ret = av_get_packet(s->pb, pkt, size);

99 pkt->stream_index = 0;

100 pkt->pos = pos;

101 } else {

102 av_log(s, AV_LOG_ERROR, "unknown chunk %x\n", type);

103 avio_skip(s->pb, size);

104 ret = AVERROR_INVALIDDATA;

105 }

106

107 return ret;

108 }

109

110 AVInputFormat ff_ast_demuxer = {

111 .name = "ast",

112 .long_name = NULL_IF_CONFIG_SMALL("AST (Audio Stream)"),

113 .read_probe = ast_probe,

114 .read_header = ast_read_header,

115 .read_packet = ast_read_packet,

116 .extensions = "ast",

117 .flags = AVFMT_GENERIC_INDEX,

118 .codec_tag = (const AVCodecTag* const []){ff_codec_ast_tags, 0},

119 };

Generated on Sat Jan 25 2014 19:52:02 for FFmpeg by doxygen 1.8.2