Libav 0.7.1
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00001 /* 00002 * Musepack SV8 demuxer 00003 * Copyright (c) 2007 Konstantin Shishkov 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav 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 * Libav 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 Libav; 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 "libavcodec/unary.h" 00024 #include "avformat.h" 00025 #include "avio_internal.h" 00026 00028 #define MKMPCTAG(a, b) (a | (b << 8)) 00029 00030 #define TAG_MPCK MKTAG('M','P','C','K') 00031 00033 enum MPCPacketTags{ 00034 TAG_STREAMHDR = MKMPCTAG('S','H'), 00035 TAG_STREAMEND = MKMPCTAG('S','E'), 00036 00037 TAG_AUDIOPACKET = MKMPCTAG('A','P'), 00038 00039 TAG_SEEKTBLOFF = MKMPCTAG('S','O'), 00040 TAG_SEEKTABLE = MKMPCTAG('S','T'), 00041 00042 TAG_REPLAYGAIN = MKMPCTAG('R','G'), 00043 TAG_ENCINFO = MKMPCTAG('E','I'), 00044 }; 00045 00046 static const int mpc8_rate[8] = { 44100, 48000, 37800, 32000, -1, -1, -1, -1 }; 00047 00048 typedef struct { 00049 int ver; 00050 int frame; 00051 int64_t header_pos; 00052 int64_t samples; 00053 } MPCContext; 00054 00055 static inline int64_t bs_get_v(uint8_t **bs) 00056 { 00057 int64_t v = 0; 00058 int br = 0; 00059 int c; 00060 00061 do { 00062 c = **bs; (*bs)++; 00063 v <<= 7; 00064 v |= c & 0x7F; 00065 br++; 00066 if (br > 10) 00067 return -1; 00068 } while (c & 0x80); 00069 00070 return v - br; 00071 } 00072 00073 static int mpc8_probe(AVProbeData *p) 00074 { 00075 uint8_t *bs = p->buf + 4; 00076 uint8_t *bs_end = bs + p->buf_size; 00077 int64_t size; 00078 00079 if (p->buf_size < 16) 00080 return 0; 00081 if (AV_RL32(p->buf) != TAG_MPCK) 00082 return 0; 00083 while (bs < bs_end + 3) { 00084 int header_found = (bs[0] == 'S' && bs[1] == 'H'); 00085 if (bs[0] < 'A' || bs[0] > 'Z' || bs[1] < 'A' || bs[1] > 'Z') 00086 return 0; 00087 bs += 2; 00088 size = bs_get_v(&bs); 00089 if (size < 2) 00090 return 0; 00091 if (bs + size - 2 >= bs_end) 00092 return AVPROBE_SCORE_MAX / 4 - 1; //seems to be valid MPC but no header yet 00093 if (header_found) { 00094 if (size < 11 || size > 28) 00095 return 0; 00096 if (!AV_RL32(bs)) //zero CRC is invalid 00097 return 0; 00098 return AVPROBE_SCORE_MAX; 00099 } else { 00100 bs += size - 2; 00101 } 00102 } 00103 return 0; 00104 } 00105 00106 static inline int64_t gb_get_v(GetBitContext *gb) 00107 { 00108 int64_t v = 0; 00109 int bits = 0; 00110 while(get_bits1(gb) && bits < 64-7){ 00111 v <<= 7; 00112 v |= get_bits(gb, 7); 00113 bits += 7; 00114 } 00115 v <<= 7; 00116 v |= get_bits(gb, 7); 00117 00118 return v; 00119 } 00120 00121 static void mpc8_get_chunk_header(AVIOContext *pb, int *tag, int64_t *size) 00122 { 00123 int64_t pos; 00124 pos = avio_tell(pb); 00125 *tag = avio_rl16(pb); 00126 *size = ffio_read_varlen(pb); 00127 *size -= avio_tell(pb) - pos; 00128 } 00129 00130 static void mpc8_parse_seektable(AVFormatContext *s, int64_t off) 00131 { 00132 MPCContext *c = s->priv_data; 00133 int tag; 00134 int64_t size, pos, ppos[2]; 00135 uint8_t *buf; 00136 int i, t, seekd; 00137 GetBitContext gb; 00138 00139 avio_seek(s->pb, off, SEEK_SET); 00140 mpc8_get_chunk_header(s->pb, &tag, &size); 00141 if(tag != TAG_SEEKTABLE){ 00142 av_log(s, AV_LOG_ERROR, "No seek table at given position\n"); 00143 return; 00144 } 00145 if(!(buf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE))) 00146 return; 00147 avio_read(s->pb, buf, size); 00148 init_get_bits(&gb, buf, size * 8); 00149 size = gb_get_v(&gb); 00150 if(size > UINT_MAX/4 || size > c->samples/1152){ 00151 av_log(s, AV_LOG_ERROR, "Seek table is too big\n"); 00152 return; 00153 } 00154 seekd = get_bits(&gb, 4); 00155 for(i = 0; i < 2; i++){ 00156 pos = gb_get_v(&gb) + c->header_pos; 00157 ppos[1 - i] = pos; 00158 av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME); 00159 } 00160 for(; i < size; i++){ 00161 t = get_unary(&gb, 1, 33) << 12; 00162 t += get_bits(&gb, 12); 00163 if(t & 1) 00164 t = -(t & ~1); 00165 pos = (t >> 1) + ppos[0]*2 - ppos[1]; 00166 av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME); 00167 ppos[1] = ppos[0]; 00168 ppos[0] = pos; 00169 } 00170 av_free(buf); 00171 } 00172 00173 static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size) 00174 { 00175 AVIOContext *pb = s->pb; 00176 int64_t pos, off; 00177 00178 switch(tag){ 00179 case TAG_SEEKTBLOFF: 00180 pos = avio_tell(pb) + size; 00181 off = ffio_read_varlen(pb); 00182 mpc8_parse_seektable(s, chunk_pos + off); 00183 avio_seek(pb, pos, SEEK_SET); 00184 break; 00185 default: 00186 avio_skip(pb, size); 00187 } 00188 } 00189 00190 static int mpc8_read_header(AVFormatContext *s, AVFormatParameters *ap) 00191 { 00192 MPCContext *c = s->priv_data; 00193 AVIOContext *pb = s->pb; 00194 AVStream *st; 00195 int tag = 0; 00196 int64_t size, pos; 00197 00198 c->header_pos = avio_tell(pb); 00199 if(avio_rl32(pb) != TAG_MPCK){ 00200 av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n"); 00201 return -1; 00202 } 00203 00204 while(!pb->eof_reached){ 00205 pos = avio_tell(pb); 00206 mpc8_get_chunk_header(pb, &tag, &size); 00207 if(tag == TAG_STREAMHDR) 00208 break; 00209 mpc8_handle_chunk(s, tag, pos, size); 00210 } 00211 if(tag != TAG_STREAMHDR){ 00212 av_log(s, AV_LOG_ERROR, "Stream header not found\n"); 00213 return -1; 00214 } 00215 pos = avio_tell(pb); 00216 avio_skip(pb, 4); //CRC 00217 c->ver = avio_r8(pb); 00218 if(c->ver != 8){ 00219 av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver); 00220 return -1; 00221 } 00222 c->samples = ffio_read_varlen(pb); 00223 ffio_read_varlen(pb); //silence samples at the beginning 00224 00225 st = av_new_stream(s, 0); 00226 if (!st) 00227 return AVERROR(ENOMEM); 00228 st->codec->codec_type = AVMEDIA_TYPE_AUDIO; 00229 st->codec->codec_id = CODEC_ID_MUSEPACK8; 00230 st->codec->bits_per_coded_sample = 16; 00231 00232 st->codec->extradata_size = 2; 00233 st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE); 00234 avio_read(pb, st->codec->extradata, st->codec->extradata_size); 00235 00236 st->codec->channels = (st->codec->extradata[1] >> 4) + 1; 00237 st->codec->sample_rate = mpc8_rate[st->codec->extradata[0] >> 5]; 00238 av_set_pts_info(st, 32, 1152 << (st->codec->extradata[1]&3)*2, st->codec->sample_rate); 00239 st->duration = c->samples / (1152 << (st->codec->extradata[1]&3)*2); 00240 size -= avio_tell(pb) - pos; 00241 00242 return 0; 00243 } 00244 00245 static int mpc8_read_packet(AVFormatContext *s, AVPacket *pkt) 00246 { 00247 MPCContext *c = s->priv_data; 00248 int tag; 00249 int64_t pos, size; 00250 00251 while(!s->pb->eof_reached){ 00252 pos = avio_tell(s->pb); 00253 mpc8_get_chunk_header(s->pb, &tag, &size); 00254 if (size < 0) 00255 return -1; 00256 if(tag == TAG_AUDIOPACKET){ 00257 if(av_get_packet(s->pb, pkt, size) < 0) 00258 return AVERROR(ENOMEM); 00259 pkt->stream_index = 0; 00260 pkt->pts = c->frame; 00261 return 0; 00262 } 00263 if(tag == TAG_STREAMEND) 00264 return AVERROR(EIO); 00265 mpc8_handle_chunk(s, tag, pos, size); 00266 } 00267 return 0; 00268 } 00269 00270 static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) 00271 { 00272 AVStream *st = s->streams[stream_index]; 00273 MPCContext *c = s->priv_data; 00274 int index = av_index_search_timestamp(st, timestamp, flags); 00275 00276 if(index < 0) return -1; 00277 avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET); 00278 c->frame = st->index_entries[index].timestamp; 00279 return 0; 00280 } 00281 00282 00283 AVInputFormat ff_mpc8_demuxer = { 00284 "mpc8", 00285 NULL_IF_CONFIG_SMALL("Musepack SV8"), 00286 sizeof(MPCContext), 00287 mpc8_probe, 00288 mpc8_read_header, 00289 mpc8_read_packet, 00290 NULL, 00291 mpc8_read_seek, 00292 };