Libav
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00001 /* 00002 * Musepack demuxer 00003 * Copyright (c) 2006 Konstantin Shishkov 00004 * 00005 * This file is part of FFmpeg. 00006 * 00007 * FFmpeg is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * FFmpeg is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with FFmpeg; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00022 #include "libavcodec/get_bits.h" 00023 #include "avformat.h" 00024 #include "id3v2.h" 00025 #include "apetag.h" 00026 00027 #define MPC_FRAMESIZE 1152 00028 #define DELAY_FRAMES 32 00029 00030 static const int mpc_rate[4] = { 44100, 48000, 37800, 32000 }; 00031 typedef struct { 00032 int64_t pos; 00033 int size, skip; 00034 }MPCFrame; 00035 00036 typedef struct { 00037 int ver; 00038 uint32_t curframe, lastframe; 00039 uint32_t fcount; 00040 MPCFrame *frames; 00041 int curbits; 00042 int frames_noted; 00043 } MPCContext; 00044 00045 static int mpc_probe(AVProbeData *p) 00046 { 00047 const uint8_t *d = p->buf; 00048 if (ff_id3v2_match(d)) { 00049 d += ff_id3v2_tag_len(d); 00050 } 00051 if (d+3 < p->buf+p->buf_size) 00052 if (d[0] == 'M' && d[1] == 'P' && d[2] == '+' && (d[3] == 0x17 || d[3] == 0x7)) 00053 return AVPROBE_SCORE_MAX; 00054 return 0; 00055 } 00056 00057 static int mpc_read_header(AVFormatContext *s, AVFormatParameters *ap) 00058 { 00059 MPCContext *c = s->priv_data; 00060 AVStream *st; 00061 int t, ret; 00062 int64_t pos = url_ftell(s->pb); 00063 00064 t = get_le24(s->pb); 00065 if(t != MKTAG('M', 'P', '+', 0)){ 00066 uint8_t buf[ID3v2_HEADER_SIZE]; 00067 if (url_fseek(s->pb, pos, SEEK_SET) < 0) 00068 return -1; 00069 ret = get_buffer(s->pb, buf, ID3v2_HEADER_SIZE); 00070 if (ret != ID3v2_HEADER_SIZE || !ff_id3v2_match(buf)) { 00071 av_log(s, AV_LOG_ERROR, "Not a Musepack file\n"); 00072 return -1; 00073 } 00074 /* skip ID3 tags and try again */ 00075 t = ff_id3v2_tag_len(buf) - ID3v2_HEADER_SIZE; 00076 av_log(s, AV_LOG_DEBUG, "Skipping %d(%X) bytes of ID3 data\n", t, t); 00077 url_fskip(s->pb, t); 00078 if(get_le24(s->pb) != MKTAG('M', 'P', '+', 0)){ 00079 av_log(s, AV_LOG_ERROR, "Not a Musepack file\n"); 00080 return -1; 00081 } 00082 /* read ID3 tags */ 00083 if (url_fseek(s->pb, pos, SEEK_SET) < 0) 00084 return -1; 00085 ff_id3v2_read(s); 00086 get_le24(s->pb); 00087 } 00088 c->ver = get_byte(s->pb); 00089 if(c->ver != 0x07 && c->ver != 0x17){ 00090 av_log(s, AV_LOG_ERROR, "Can demux Musepack SV7, got version %02X\n", c->ver); 00091 return -1; 00092 } 00093 c->fcount = get_le32(s->pb); 00094 if((int64_t)c->fcount * sizeof(MPCFrame) >= UINT_MAX){ 00095 av_log(s, AV_LOG_ERROR, "Too many frames, seeking is not possible\n"); 00096 return -1; 00097 } 00098 c->frames = av_malloc(c->fcount * sizeof(MPCFrame)); 00099 c->curframe = 0; 00100 c->lastframe = -1; 00101 c->curbits = 8; 00102 c->frames_noted = 0; 00103 00104 st = av_new_stream(s, 0); 00105 if (!st) 00106 return AVERROR(ENOMEM); 00107 st->codec->codec_type = AVMEDIA_TYPE_AUDIO; 00108 st->codec->codec_id = CODEC_ID_MUSEPACK7; 00109 st->codec->channels = 2; 00110 st->codec->bits_per_coded_sample = 16; 00111 00112 st->codec->extradata_size = 16; 00113 st->codec->extradata = av_mallocz(st->codec->extradata_size+FF_INPUT_BUFFER_PADDING_SIZE); 00114 get_buffer(s->pb, st->codec->extradata, 16); 00115 st->codec->sample_rate = mpc_rate[st->codec->extradata[2] & 3]; 00116 av_set_pts_info(st, 32, MPC_FRAMESIZE, st->codec->sample_rate); 00117 /* scan for seekpoints */ 00118 st->start_time = 0; 00119 st->duration = c->fcount; 00120 00121 /* try to read APE tags */ 00122 if (!url_is_streamed(s->pb)) { 00123 int64_t pos = url_ftell(s->pb); 00124 ff_ape_parse_tag(s); 00125 url_fseek(s->pb, pos, SEEK_SET); 00126 } 00127 00128 return 0; 00129 } 00130 00131 static int mpc_read_packet(AVFormatContext *s, AVPacket *pkt) 00132 { 00133 MPCContext *c = s->priv_data; 00134 int ret, size, size2, curbits, cur = c->curframe; 00135 int64_t tmp, pos; 00136 00137 if (c->curframe >= c->fcount) 00138 return -1; 00139 00140 if(c->curframe != c->lastframe + 1){ 00141 url_fseek(s->pb, c->frames[c->curframe].pos, SEEK_SET); 00142 c->curbits = c->frames[c->curframe].skip; 00143 } 00144 c->lastframe = c->curframe; 00145 c->curframe++; 00146 curbits = c->curbits; 00147 pos = url_ftell(s->pb); 00148 tmp = get_le32(s->pb); 00149 if(curbits <= 12){ 00150 size2 = (tmp >> (12 - curbits)) & 0xFFFFF; 00151 }else{ 00152 tmp = (tmp << 32) | get_le32(s->pb); 00153 size2 = (tmp >> (44 - curbits)) & 0xFFFFF; 00154 } 00155 curbits += 20; 00156 url_fseek(s->pb, pos, SEEK_SET); 00157 00158 size = ((size2 + curbits + 31) & ~31) >> 3; 00159 if(cur == c->frames_noted){ 00160 c->frames[cur].pos = pos; 00161 c->frames[cur].size = size; 00162 c->frames[cur].skip = curbits - 20; 00163 av_add_index_entry(s->streams[0], cur, cur, size, 0, AVINDEX_KEYFRAME); 00164 c->frames_noted++; 00165 } 00166 c->curbits = (curbits + size2) & 0x1F; 00167 00168 if (av_new_packet(pkt, size) < 0) 00169 return AVERROR(EIO); 00170 00171 pkt->data[0] = curbits; 00172 pkt->data[1] = (c->curframe > c->fcount); 00173 pkt->data[2] = 0; 00174 pkt->data[3] = 0; 00175 00176 pkt->stream_index = 0; 00177 pkt->pts = cur; 00178 ret = get_buffer(s->pb, pkt->data + 4, size); 00179 if(c->curbits) 00180 url_fseek(s->pb, -4, SEEK_CUR); 00181 if(ret < size){ 00182 av_free_packet(pkt); 00183 return AVERROR(EIO); 00184 } 00185 pkt->size = ret + 4; 00186 00187 return 0; 00188 } 00189 00190 static int mpc_read_close(AVFormatContext *s) 00191 { 00192 MPCContext *c = s->priv_data; 00193 00194 av_freep(&c->frames); 00195 return 0; 00196 } 00197 00205 static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) 00206 { 00207 AVStream *st = s->streams[stream_index]; 00208 MPCContext *c = s->priv_data; 00209 AVPacket pkt1, *pkt = &pkt1; 00210 int ret; 00211 int index = av_index_search_timestamp(st, timestamp - DELAY_FRAMES, flags); 00212 uint32_t lastframe; 00213 00214 /* if found, seek there */ 00215 if (index >= 0){ 00216 c->curframe = st->index_entries[index].pos; 00217 return 0; 00218 } 00219 /* if timestamp is out of bounds, return error */ 00220 if(timestamp < 0 || timestamp >= c->fcount) 00221 return -1; 00222 timestamp -= DELAY_FRAMES; 00223 /* seek to the furthest known position and read packets until 00224 we reach desired position */ 00225 lastframe = c->curframe; 00226 if(c->frames_noted) c->curframe = c->frames_noted - 1; 00227 while(c->curframe < timestamp){ 00228 ret = av_read_frame(s, pkt); 00229 if (ret < 0){ 00230 c->curframe = lastframe; 00231 return -1; 00232 } 00233 av_free_packet(pkt); 00234 } 00235 return 0; 00236 } 00237 00238 00239 AVInputFormat mpc_demuxer = { 00240 "mpc", 00241 NULL_IF_CONFIG_SMALL("Musepack"), 00242 sizeof(MPCContext), 00243 mpc_probe, 00244 mpc_read_header, 00245 mpc_read_packet, 00246 mpc_read_close, 00247 mpc_read_seek, 00248 .extensions = "mpc", 00249 };