Libav 0.7.1
libavformat/mpc.c
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00001 /*
00002  * Musepack demuxer
00003  * Copyright (c) 2006 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 "avformat.h"
00024 #include "apetag.h"
00025 #include "id3v1.h"
00026 #include "libavutil/dict.h"
00027 
00028 #define MPC_FRAMESIZE  1152
00029 #define DELAY_FRAMES   32
00030 
00031 static const int mpc_rate[4] = { 44100, 48000, 37800, 32000 };
00032 typedef struct {
00033     int64_t pos;
00034     int size, skip;
00035 }MPCFrame;
00036 
00037 typedef struct {
00038     int ver;
00039     uint32_t curframe, lastframe;
00040     uint32_t fcount;
00041     MPCFrame *frames;
00042     int curbits;
00043     int frames_noted;
00044 } MPCContext;
00045 
00046 static int mpc_probe(AVProbeData *p)
00047 {
00048     const uint8_t *d = p->buf;
00049     if (d[0] == 'M' && d[1] == 'P' && d[2] == '+' && (d[3] == 0x17 || d[3] == 0x7))
00050         return AVPROBE_SCORE_MAX;
00051     return 0;
00052 }
00053 
00054 static int mpc_read_header(AVFormatContext *s, AVFormatParameters *ap)
00055 {
00056     MPCContext *c = s->priv_data;
00057     AVStream *st;
00058 
00059     if(avio_rl24(s->pb) != MKTAG('M', 'P', '+', 0)){
00060         av_log(s, AV_LOG_ERROR, "Not a Musepack file\n");
00061         return -1;
00062     }
00063     c->ver = avio_r8(s->pb);
00064     if(c->ver != 0x07 && c->ver != 0x17){
00065         av_log(s, AV_LOG_ERROR, "Can demux Musepack SV7, got version %02X\n", c->ver);
00066         return -1;
00067     }
00068     c->fcount = avio_rl32(s->pb);
00069     if((int64_t)c->fcount * sizeof(MPCFrame) >= UINT_MAX){
00070         av_log(s, AV_LOG_ERROR, "Too many frames, seeking is not possible\n");
00071         return -1;
00072     }
00073     c->frames = av_malloc(c->fcount * sizeof(MPCFrame));
00074     c->curframe = 0;
00075     c->lastframe = -1;
00076     c->curbits = 8;
00077     c->frames_noted = 0;
00078 
00079     st = av_new_stream(s, 0);
00080     if (!st)
00081         return AVERROR(ENOMEM);
00082     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
00083     st->codec->codec_id = CODEC_ID_MUSEPACK7;
00084     st->codec->channels = 2;
00085     st->codec->bits_per_coded_sample = 16;
00086 
00087     st->codec->extradata_size = 16;
00088     st->codec->extradata = av_mallocz(st->codec->extradata_size+FF_INPUT_BUFFER_PADDING_SIZE);
00089     avio_read(s->pb, st->codec->extradata, 16);
00090     st->codec->sample_rate = mpc_rate[st->codec->extradata[2] & 3];
00091     av_set_pts_info(st, 32, MPC_FRAMESIZE, st->codec->sample_rate);
00092     /* scan for seekpoints */
00093     st->start_time = 0;
00094     st->duration = c->fcount;
00095 
00096     /* try to read APE tags */
00097     if (s->pb->seekable) {
00098         int64_t pos = avio_tell(s->pb);
00099         ff_ape_parse_tag(s);
00100         if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
00101             ff_id3v1_read(s);
00102         avio_seek(s->pb, pos, SEEK_SET);
00103     }
00104 
00105     return 0;
00106 }
00107 
00108 static int mpc_read_packet(AVFormatContext *s, AVPacket *pkt)
00109 {
00110     MPCContext *c = s->priv_data;
00111     int ret, size, size2, curbits, cur = c->curframe;
00112     int64_t tmp, pos;
00113 
00114     if (c->curframe >= c->fcount)
00115         return -1;
00116 
00117     if(c->curframe != c->lastframe + 1){
00118         avio_seek(s->pb, c->frames[c->curframe].pos, SEEK_SET);
00119         c->curbits = c->frames[c->curframe].skip;
00120     }
00121     c->lastframe = c->curframe;
00122     c->curframe++;
00123     curbits = c->curbits;
00124     pos = avio_tell(s->pb);
00125     tmp = avio_rl32(s->pb);
00126     if(curbits <= 12){
00127         size2 = (tmp >> (12 - curbits)) & 0xFFFFF;
00128     }else{
00129         tmp = (tmp << 32) | avio_rl32(s->pb);
00130         size2 = (tmp >> (44 - curbits)) & 0xFFFFF;
00131     }
00132     curbits += 20;
00133     avio_seek(s->pb, pos, SEEK_SET);
00134 
00135     size = ((size2 + curbits + 31) & ~31) >> 3;
00136     if(cur == c->frames_noted){
00137         c->frames[cur].pos = pos;
00138         c->frames[cur].size = size;
00139         c->frames[cur].skip = curbits - 20;
00140         av_add_index_entry(s->streams[0], cur, cur, size, 0, AVINDEX_KEYFRAME);
00141         c->frames_noted++;
00142     }
00143     c->curbits = (curbits + size2) & 0x1F;
00144 
00145     if (av_new_packet(pkt, size) < 0)
00146         return AVERROR(EIO);
00147 
00148     pkt->data[0] = curbits;
00149     pkt->data[1] = (c->curframe > c->fcount);
00150     pkt->data[2] = 0;
00151     pkt->data[3] = 0;
00152 
00153     pkt->stream_index = 0;
00154     pkt->pts = cur;
00155     ret = avio_read(s->pb, pkt->data + 4, size);
00156     if(c->curbits)
00157         avio_seek(s->pb, -4, SEEK_CUR);
00158     if(ret < size){
00159         av_free_packet(pkt);
00160         return AVERROR(EIO);
00161     }
00162     pkt->size = ret + 4;
00163 
00164     return 0;
00165 }
00166 
00167 static int mpc_read_close(AVFormatContext *s)
00168 {
00169     MPCContext *c = s->priv_data;
00170 
00171     av_freep(&c->frames);
00172     return 0;
00173 }
00174 
00182 static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
00183 {
00184     AVStream *st = s->streams[stream_index];
00185     MPCContext *c = s->priv_data;
00186     AVPacket pkt1, *pkt = &pkt1;
00187     int ret;
00188     int index = av_index_search_timestamp(st, timestamp - DELAY_FRAMES, flags);
00189     uint32_t lastframe;
00190 
00191     /* if found, seek there */
00192     if (index >= 0){
00193         c->curframe = st->index_entries[index].pos;
00194         return 0;
00195     }
00196     /* if timestamp is out of bounds, return error */
00197     if(timestamp < 0 || timestamp >= c->fcount)
00198         return -1;
00199     timestamp -= DELAY_FRAMES;
00200     /* seek to the furthest known position and read packets until
00201        we reach desired position */
00202     lastframe = c->curframe;
00203     if(c->frames_noted) c->curframe = c->frames_noted - 1;
00204     while(c->curframe < timestamp){
00205         ret = av_read_frame(s, pkt);
00206         if (ret < 0){
00207             c->curframe = lastframe;
00208             return -1;
00209         }
00210         av_free_packet(pkt);
00211     }
00212     return 0;
00213 }
00214 
00215 
00216 AVInputFormat ff_mpc_demuxer = {
00217     "mpc",
00218     NULL_IF_CONFIG_SMALL("Musepack"),
00219     sizeof(MPCContext),
00220     mpc_probe,
00221     mpc_read_header,
00222     mpc_read_packet,
00223     mpc_read_close,
00224     mpc_read_seek,
00225     .extensions = "mpc",
00226 };