FFmpeg: libavformat/mpc.c Source File

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libavformat

mpc.c

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1 /*

2 * Musepack 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 "libavcodec/get_bits.h"

24 #include "avformat.h"

25 #include "internal.h"

26 #include "apetag.h"

27 #include "id3v1.h"

28 #include "libavutil/dict.h"

30 #define MPC_FRAMESIZE 1152

31 #define DELAY_FRAMES 32

33 static const int mpc_rate[4] = { 44100, 48000, 37800, 32000 };

34 typedef struct {

35 int64_t pos;

36 int size, skip;

37 }MPCFrame;

39 typedef struct {

40 int ver;

41 uint32_t curframe, lastframe;

42 uint32_t fcount;

43 MPCFrame *frames;

44 int curbits;

45 int frames_noted;

46 } MPCContext;

48 static int mpc_probe(AVProbeData *p)

49 {

50 const uint8_t *d = p->buf;

51 if (d[0] == 'M' && d[1] == 'P' && d[2] == '+' && (d[3] == 0x17 || d[3] == 0x7))

52 return AVPROBE_SCORE_MAX;

53 return 0;

54 }

56 static int mpc_read_header(AVFormatContext *s)

57 {

58 MPCContext *c = s->priv_data;

59 AVStream *st;

61 if(avio_rl24(s->pb) != MKTAG('M', 'P', '+', 0)){

62 av_log(s, AV_LOG_ERROR, "Not a Musepack file\n");

63 return AVERROR_INVALIDDATA;

64 }

65 c->ver = avio_r8(s->pb);

66 if(c->ver != 0x07 && c->ver != 0x17){

67 av_log(s, AV_LOG_ERROR, "Can demux Musepack SV7, got version %02X\n", c->ver);

68 return AVERROR_INVALIDDATA;

69 }

70 c->fcount = avio_rl32(s->pb);

71 if((int64_t)c->fcount * sizeof(MPCFrame) >= UINT_MAX){

72 av_log(s, AV_LOG_ERROR, "Too many frames, seeking is not possible\n");

73 return AVERROR_INVALIDDATA;

74 }

75 if(c->fcount){

76 c->frames = av_malloc(c->fcount * sizeof(MPCFrame));

77 if(!c->frames){

78 av_log(s, AV_LOG_ERROR, "Cannot allocate seektable\n");

79 return AVERROR(ENOMEM);

80 }

81 }else{

82 av_log(s, AV_LOG_WARNING, "Container reports no frames\n");

83 }

84 c->curframe = 0;

85 c->lastframe = -1;

86 c->curbits = 8;

87 c->frames_noted = 0;

89 st = avformat_new_stream(s, NULL);

90 if (!st)

91 return AVERROR(ENOMEM);

92 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

93 st->codec->codec_id = AV_CODEC_ID_MUSEPACK7;

94 st->codec->channels = 2;

95 st->codec->channel_layout = AV_CH_LAYOUT_STEREO;

96 st->codec->bits_per_coded_sample = 16;

98 if (ff_get_extradata(st->codec, s->pb, 16) < 0)

99 return AVERROR(ENOMEM);

100 st->codec->sample_rate = mpc_rate[st->codec->extradata[2] & 3];

101 avpriv_set_pts_info(st, 32, MPC_FRAMESIZE, st->codec->sample_rate);

102 /* scan for seekpoints */

103 st->start_time = 0;

104 st->duration = c->fcount;

105

106 /* try to read APE tags */

107 if (s->pb->seekable) {

108 int64_t pos = avio_tell(s->pb);

109 ff_ape_parse_tag(s);

110 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))

111 ff_id3v1_read(s);

112 avio_seek(s->pb, pos, SEEK_SET);

113 }

114

115 return 0;

116 }

117

118 static int mpc_read_packet(AVFormatContext *s, AVPacket *pkt)

119 {

120 MPCContext *c = s->priv_data;

121 int ret, size, size2, curbits, cur = c->curframe;

122 unsigned tmp;

123 int64_t pos;

124

125 if (c->curframe >= c->fcount && c->fcount)

126 return AVERROR_EOF;

127

128 if(c->curframe != c->lastframe + 1){

129 avio_seek(s->pb, c->frames[c->curframe].pos, SEEK_SET);

130 c->curbits = c->frames[c->curframe].skip;

131 }

132 c->lastframe = c->curframe;

133 c->curframe++;

134 curbits = c->curbits;

135 pos = avio_tell(s->pb);

136 tmp = avio_rl32(s->pb);

137 if(curbits <= 12){

138 size2 = (tmp >> (12 - curbits)) & 0xFFFFF;

139 }else{

140 size2 = (tmp << (curbits - 12) | avio_rl32(s->pb) >> (44 - curbits)) & 0xFFFFF;

141 }

142 curbits += 20;

143 avio_seek(s->pb, pos, SEEK_SET);

144

145 size = ((size2 + curbits + 31) & ~31) >> 3;

146 if(cur == c->frames_noted && c->fcount){

147 c->frames[cur].pos = pos;

148 c->frames[cur].size = size;

149 c->frames[cur].skip = curbits - 20;

150 av_add_index_entry(s->streams[0], cur, cur, size, 0, AVINDEX_KEYFRAME);

151 c->frames_noted++;

152 }

153 c->curbits = (curbits + size2) & 0x1F;

154

155 if ((ret = av_new_packet(pkt, size + 4)) < 0)

156 return ret;

157

158 pkt->data[0] = curbits;

159 pkt->data[1] = (c->curframe > c->fcount) && c->fcount;

160 pkt->data[2] = 0;

161 pkt->data[3] = 0;

162

163 pkt->stream_index = 0;

164 pkt->pts = cur;

165 ret = avio_read(s->pb, pkt->data + 4, size);

166 if(c->curbits)

167 avio_seek(s->pb, -4, SEEK_CUR);

168 if(ret < size){

169 av_free_packet(pkt);

170 return ret < 0 ? ret : AVERROR(EIO);

171 }

172 pkt->size = ret + 4;

173

174 return 0;

175 }

176

177 static int mpc_read_close(AVFormatContext *s)

178 {

179 MPCContext *c = s->priv_data;

180

181 av_freep(&c->frames);

182 return 0;

183 }

184

185 /**

186 * Seek to the given position

187 * If position is unknown but is within the limits of file

188 * then packets are skipped unless desired position is reached

189 *

190 * Also this function makes use of the fact that timestamp == frameno

191 */

192 static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)

193 {

194 AVStream *st = s->streams[stream_index];

195 MPCContext *c = s->priv_data;

196 AVPacket pkt1, *pkt = &pkt1;

197 int ret;

198 int index = av_index_search_timestamp(st, FFMAX(timestamp - DELAY_FRAMES, 0), flags);

199 uint32_t lastframe;

200

201 /* if found, seek there */

202 if (index >= 0 && st->index_entries[st->nb_index_entries-1].timestamp >= timestamp - DELAY_FRAMES){

203 c->curframe = st->index_entries[index].pos;

204 return 0;

205 }

206 /* if timestamp is out of bounds, return error */

207 if(timestamp < 0 || timestamp >= c->fcount)

208 return -1;

209 timestamp -= DELAY_FRAMES;

210 /* seek to the furthest known position and read packets until

211 we reach desired position */

212 lastframe = c->curframe;

213 if(c->frames_noted) c->curframe = c->frames_noted - 1;

214 while(c->curframe < timestamp){

215 ret = av_read_frame(s, pkt);

216 if (ret < 0){

217 c->curframe = lastframe;

218 return ret;

219 }

220 av_free_packet(pkt);

221 }

222 return 0;

223 }

224

225

226 AVInputFormat ff_mpc_demuxer = {

227 .name = "mpc",

228 .long_name = NULL_IF_CONFIG_SMALL("Musepack"),

229 .priv_data_size = sizeof(MPCContext),

230 .read_probe = mpc_probe,

231 .read_header = mpc_read_header,

232 .read_packet = mpc_read_packet,

233 .read_close = mpc_read_close,

234 .read_seek = mpc_read_seek,

235 .extensions = "mpc",

236 };

Generated on Sun Jul 20 2014 23:05:51 for FFmpeg by doxygen 1.8.2