FFmpeg: libavformat/astdec.c Source File

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libavformat

astdec.c

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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 return 0;

33 if (!AV_RB16(p->buf + 10) ||

34 !AV_RB16(p->buf + 12) || AV_RB16(p->buf + 12) > 256 ||

35 !AV_RB32(p->buf + 16) || AV_RB32(p->buf + 16) > 8*48000)

36 return AVPROBE_SCORE_MAX / 8;

38 return AVPROBE_SCORE_MAX / 3 * 2;

39 }

41 static int ast_read_header(AVFormatContext *s)

42 {

43 int depth;

44 AVStream *st;

46 st = avformat_new_stream(s, NULL);

47 if (!st)

48 return AVERROR(ENOMEM);

50 avio_skip(s->pb, 8);

51 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

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

54 depth = avio_rb16(s->pb);

55 if (depth != 16) {

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

57 return AVERROR_INVALIDDATA;

58 }

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

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

62 return AVERROR_INVALIDDATA;

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

65 st->codec->channel_layout = AV_CH_LAYOUT_STEREO;

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

67 st->codec->channel_layout = AV_CH_LAYOUT_4POINT0;

69 avio_skip(s->pb, 2);

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

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

72 return AVERROR_INVALIDDATA;

73 st->start_time = 0;

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

75 avio_skip(s->pb, 40);

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

78 return 0;

79 }

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

82 {

83 uint32_t type, size;

84 int64_t pos;

85 int ret;

87 if (url_feof(s->pb))

88 return AVERROR_EOF;

90 pos = avio_tell(s->pb);

91 type = avio_rl32(s->pb);

92 size = avio_rb32(s->pb);

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

94 return AVERROR_INVALIDDATA;

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

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

98 return ret;

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

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

102 pkt->stream_index = 0;

103 pkt->pos = pos;

104 } else {

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

106 avio_skip(s->pb, size);

107 ret = AVERROR_INVALIDDATA;

108 }

109

110 return ret;

111 }

112

113 AVInputFormat ff_ast_demuxer = {

114 .name = "ast",

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

116 .read_probe = ast_probe,

117 .read_header = ast_read_header,

118 .read_packet = ast_read_packet,

119 .extensions = "ast",

120 .flags = AVFMT_GENERIC_INDEX,

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

122 };

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