FFmpeg: libavformat/iss.c Source File

FFmpeg

[フレーム]

libavformat

iss.c

Go to the documentation of this file.

1 /*

2 * ISS (.iss) file 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 /**

23 * @file

24 * Funcom ISS file demuxer

25 * @author Jaikrishnan Menon

26 * @see http://wiki.multimedia.cx/index.php?title=FunCom_ISS

27 */

29 #include "libavutil/channel_layout.h"

30 #include "avformat.h"

31 #include "internal.h"

32 #include "libavutil/avstring.h"

34 #define ISS_SIG "IMA_ADPCM_Sound"

35 #define ISS_SIG_LEN 15

36 #define MAX_TOKEN_SIZE 20

38 typedef struct {

39 int packet_size;

40 int sample_start_pos;

41 } IssDemuxContext;

43 static void get_token(AVIOContext *s, char *buf, int maxlen)

44 {

45 int i = 0;

46 char c;

48 while ((c = avio_r8(s))) {

49 if(c == ' ')

50 break;

51 if (i < maxlen-1)

52 buf[i++] = c;

53 }

55 if(!c)

56 avio_r8(s);

58 buf[i] = 0; /* Ensure null terminated, but may be truncated */

59 }

61 static int iss_probe(AVProbeData *p)

62 {

63 if (strncmp(p->buf, ISS_SIG, ISS_SIG_LEN))

64 return 0;

66 return AVPROBE_SCORE_MAX;

67 }

69 static av_cold int iss_read_header(AVFormatContext *s)

70 {

71 IssDemuxContext *iss = s->priv_data;

72 AVIOContext *pb = s->pb;

73 AVStream *st;

74 char token[MAX_TOKEN_SIZE];

75 int stereo, rate_divisor;

77 get_token(pb, token, sizeof(token)); //"IMA_ADPCM_Sound"

78 get_token(pb, token, sizeof(token)); //packet size

79 sscanf(token, "%d", &iss->packet_size);

80 get_token(pb, token, sizeof(token)); //File ID

81 get_token(pb, token, sizeof(token)); //out size

82 get_token(pb, token, sizeof(token)); //stereo

83 sscanf(token, "%d", &stereo);

84 get_token(pb, token, sizeof(token)); //Unknown1

85 get_token(pb, token, sizeof(token)); //RateDivisor

86 sscanf(token, "%d", &rate_divisor);

87 get_token(pb, token, sizeof(token)); //Unknown2

88 get_token(pb, token, sizeof(token)); //Version ID

89 get_token(pb, token, sizeof(token)); //Size

91 if (iss->packet_size <= 0) {

92 av_log(s, AV_LOG_ERROR, "packet_size %d is invalid\n", iss->packet_size);

93 return AVERROR_INVALIDDATA;

94 }

96 iss->sample_start_pos = avio_tell(pb);

98 st = avformat_new_stream(s, NULL);

99 if (!st)

100 return AVERROR(ENOMEM);

101 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

102 st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_ISS;

103 if (stereo) {

104 st->codec->channels = 2;

105 st->codec->channel_layout = AV_CH_LAYOUT_STEREO;

106 } else {

107 st->codec->channels = 1;

108 st->codec->channel_layout = AV_CH_LAYOUT_MONO;

109 }

110 st->codec->sample_rate = 44100;

111 if(rate_divisor > 0)

112 st->codec->sample_rate /= rate_divisor;

113 st->codec->bits_per_coded_sample = 4;

114 st->codec->bit_rate = st->codec->channels * st->codec->sample_rate

115 * st->codec->bits_per_coded_sample;

116 st->codec->block_align = iss->packet_size;

117 avpriv_set_pts_info(st, 32, 1, st->codec->sample_rate);

118

119 return 0;

120 }

121

122 static int iss_read_packet(AVFormatContext *s, AVPacket *pkt)

123 {

124 IssDemuxContext *iss = s->priv_data;

125 int ret = av_get_packet(s->pb, pkt, iss->packet_size);

126

127 if(ret != iss->packet_size)

128 return AVERROR(EIO);

129

130 pkt->stream_index = 0;

131 pkt->pts = avio_tell(s->pb) - iss->sample_start_pos;

132 if(s->streams[0]->codec->channels > 0)

133 pkt->pts /= s->streams[0]->codec->channels*2;

134 return 0;

135 }

136

137 AVInputFormat ff_iss_demuxer = {

138 .name = "iss",

139 .long_name = NULL_IF_CONFIG_SMALL("Funcom ISS"),

140 .priv_data_size = sizeof(IssDemuxContext),

141 .read_probe = iss_probe,

142 .read_header = iss_read_header,

143 .read_packet = iss_read_packet,

144 };

Generated on Wed Jul 10 2013 23:48:12 for FFmpeg by doxygen 1.8.2