FFmpeg: libavformat/mpc8.c Source File

00001 /*
00002  * Musepack SV8 demuxer
00003  * Copyright (c) 2007 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 "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(!url_feof(pb)){
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(!url_feof(s->pb)){
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 AVERROR_EOF;
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 };