MythTV: mpeg.c Source File

00001 /*
00002  * MPEG1/2 demuxer
00003  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard.
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 "avformat.h"
00023 #include "mpeg.h"
00024 
00025 //#define DEBUG_SEEK
00026 
00027 #undef NDEBUG
00028 #include <assert.h>
00029 
00030 /*********************************************/
00031 /* demux code */
00032 
00033 #define MAX_SYNC_SIZE 100000
00034 
00035 static int cdxa_probe(AVProbeData *p)
00036 {
00037     /* check file header */
00038     if (p->buf[0] == 'R' && p->buf[1] == 'I' &&
00039         p->buf[2] == 'F' && p->buf[3] == 'F' &&
00040         p->buf[8] == 'C' && p->buf[9] == 'D' &&
00041         p->buf[10] == 'X' && p->buf[11] == 'A')
00042         return AVPROBE_SCORE_MAX;
00043     else
00044         return 0;
00045 }
00046 
00047 static int check_pes(uint8_t *p, uint8_t *end){
00048     int pes1;
00049     int pes2=      (p[3] & 0xC0) == 0x80
00050                 && (p[4] & 0xC0) != 0x40
00051                 &&((p[4] & 0xC0) == 0x00 || (p[4]&0xC0)>>2 == (p[6]&0xF0));
00052 
00053     for(p+=3; p<end && *p == 0xFF; p++);
00054     if((*p&0xC0) == 0x40) p+=2;
00055     if((*p&0xF0) == 0x20){
00056         pes1= p[0]&p[2]&p[4]&1;
00057         p+=5;
00058     }else if((*p&0xF0) == 0x30){
00059         pes1= p[0]&p[2]&p[4]&p[5]&p[7]&p[9]&1;
00060         p+=10;
00061     }else
00062         pes1 = *p == 0x0F;
00063 
00064     return pes1||pes2;
00065 }
00066 
00067 static int mpegps_probe(AVProbeData *p)
00068 {
00069     int i;
00070     int size= FFMIN(2048, p->buf_size);
00071     uint32_t code=0xFF;
00072 
00073     /* we search the first start code. If it is a packet start code,
00074        then we decide it is mpeg ps. We do not send highest value to
00075        give a chance to mpegts */
00076     /* NOTE: the search range was restricted to avoid too many false
00077        detections */
00078 
00079     for (i = 0; i < size; i++) {
00080         code = (code << 8) | p->buf[i];
00081         if ((code & 0xffffff00) == 0x100) {
00082             if (code == PACK_START_CODE ||
00083                 code == SYSTEM_HEADER_START_CODE ||
00084                 (code >= 0x1e0 && code <= 0x1ef) ||
00085                 (code >= 0x1c0 && code <= 0x1df) ||
00086                 code == PRIVATE_STREAM_2 ||
00087                 code == PROGRAM_STREAM_MAP ||
00088                 code == PRIVATE_STREAM_1 ||
00089                 code == PADDING_STREAM ||
00090                 code >= 0x100 && code <= 0x1b0)
00091                 return AVPROBE_SCORE_MAX - 2;
00092             else
00093                 return 0;
00094         }
00095     }
00096 
00097     return 0;
00098 }
00099 
00100 typedef struct MpegDemuxContext {
00101     int32_t header_state;
00102     unsigned char psm_es_type[256];
00103     int sofdec;
00104 } MpegDemuxContext;
00105 
00106 static int mpegps_read_header(AVFormatContext *s,
00107                               AVFormatParameters *ap)
00108 {
00109     MpegDemuxContext *m = s->priv_data;
00110     const char *sofdec = "Sofdec";
00111     int v, i = 0;
00112 
00113     m->header_state = 0xff;
00114     s->ctx_flags |= AVFMTCTX_NOHEADER;
00115 
00116     m->sofdec = -1;
00117     do {
00118         v = get_byte(&s->pb);
00119         m->header_state = m->header_state << 8 | v;
00120         m->sofdec++;
00121     } while (v == sofdec[i] && i++ < 6);
00122 
00123     /* no need to do more */
00124     return 0;
00125 }
00126 
00127 static int64_t get_pts(ByteIOContext *pb, int c)
00128 {
00129     int64_t pts;
00130     int val;
00131 
00132     if (c < 0)
00133         c = get_byte(pb);
00134     pts = (int64_t)((c >> 1) & 0x07) << 30;
00135     val = get_be16(pb);
00136     pts |= (int64_t)(val >> 1) << 15;
00137     val = get_be16(pb);
00138     pts |= (int64_t)(val >> 1);
00139     return pts;
00140 }
00141 
00142 static int find_next_start_code(ByteIOContext *pb, int *size_ptr,
00143                                 int32_t *header_state)
00144 {
00145     unsigned int state, v;
00146     int val, n;
00147 
00148     state = *header_state;
00149     n = *size_ptr;
00150     while (n > 0) {
00151         if (url_feof(pb))
00152             break;
00153         v = get_byte(pb);
00154         n--;
00155         if (state == 0x000001) {
00156             state = ((state << 8) | v) & 0xffffff;
00157             val = state;
00158             goto found;
00159         }
00160         state = ((state << 8) | v) & 0xffffff;
00161     }
00162     val = -1;
00163  found:
00164     *header_state = state;
00165     *size_ptr = n;
00166     return val;
00167 }
00168 
00169 #if 0 /* unused, remove? */
00170 /* XXX: optimize */
00171 static int find_prev_start_code(ByteIOContext *pb, int *size_ptr)
00172 {
00173     int64_t pos, pos_start;
00174     int max_size, start_code;
00175 
00176     max_size = *size_ptr;
00177     pos_start = url_ftell(pb);
00178 
00179     /* in order to go faster, we fill the buffer */
00180     pos = pos_start - 16386;
00181     if (pos < 0)
00182         pos = 0;
00183     url_fseek(pb, pos, SEEK_SET);
00184     get_byte(pb);
00185 
00186     pos = pos_start;
00187     for(;;) {
00188         pos--;
00189         if (pos < 0 || (pos_start - pos) >= max_size) {
00190             start_code = -1;
00191             goto the_end;
00192         }
00193         url_fseek(pb, pos, SEEK_SET);
00194         start_code = get_be32(pb);
00195         if ((start_code & 0xffffff00) == 0x100)
00196             break;
00197     }
00198  the_end:
00199     *size_ptr = pos_start - pos;
00200     return start_code;
00201 }
00202 #endif
00203 
00210 static long mpegps_psm_parse(MpegDemuxContext *m, ByteIOContext *pb)
00211 {
00212     int psm_length, ps_info_length, es_map_length;
00213 
00214     psm_length = get_be16(pb);
00215     get_byte(pb);
00216     get_byte(pb);
00217     ps_info_length = get_be16(pb);
00218 
00219     /* skip program_stream_info */
00220     url_fskip(pb, ps_info_length);
00221     es_map_length = get_be16(pb);
00222 
00223     /* at least one es available? */
00224     while (es_map_length >= 4){
00225         unsigned char type = get_byte(pb);
00226         unsigned char es_id = get_byte(pb);
00227         uint16_t es_info_length = get_be16(pb);
00228         /* remember mapping from stream id to stream type */
00229         m->psm_es_type[es_id] = type;
00230         /* skip program_stream_info */
00231         url_fskip(pb, es_info_length);
00232         es_map_length -= 4 + es_info_length;
00233     }
00234     get_be32(pb); /* crc32 */
00235     return 2 + psm_length;
00236 }
00237 
00238 /* read the next PES header. Return its position in ppos
00239    (if not NULL), and its start code, pts and dts.
00240  */
00241 static int mpegps_read_pes_header(AVFormatContext *s,
00242                                   int64_t *ppos, int *pstart_code,
00243                                   int64_t *ppts, int64_t *pdts)
00244 {
00245     MpegDemuxContext *m = s->priv_data;
00246     int len, size, startcode, c, flags, header_len;
00247     int pes_ext, ext2_len, id_ext, skip;
00248     int64_t pts, dts;
00249     int64_t last_sync= url_ftell(&s->pb);
00250 
00251  error_redo:
00252         url_fseek(&s->pb, last_sync, SEEK_SET);
00253  redo:
00254         /* next start code (should be immediately after) */
00255         m->header_state = 0xff;
00256         size = MAX_SYNC_SIZE;
00257         startcode = find_next_start_code(&s->pb, &size, &m->header_state);
00258         last_sync = url_ftell(&s->pb);
00259     //printf("startcode=%x pos=0x%"PRIx64"\n", startcode, url_ftell(&s->pb));
00260     if (startcode < 0)
00261         return AVERROR(EIO);
00262     if (startcode == PACK_START_CODE)
00263         goto redo;
00264     if (startcode == SYSTEM_HEADER_START_CODE)
00265         goto redo;
00266     if (startcode == PADDING_STREAM) {
00267         url_fskip(&s->pb, get_be16(&s->pb));
00268         goto redo;
00269     }
00270     if (startcode == PRIVATE_STREAM_2) {
00271         len = get_be16(&s->pb);
00272         if (!m->sofdec) {
00273             while (len-- >= 6) {
00274                 if (get_byte(&s->pb) == 'S') {
00275                     uint8_t buf[5];
00276                     get_buffer(&s->pb, buf, sizeof(buf));
00277                     m->sofdec = !memcmp(buf, "ofdec", 5);
00278                     len -= sizeof(buf);
00279                     break;
00280                 }
00281             }
00282             m->sofdec -= !m->sofdec;
00283         }
00284         url_fskip(&s->pb, len);
00285         goto redo;
00286     }
00287     if (startcode == PROGRAM_STREAM_MAP) {
00288         mpegps_psm_parse(m, &s->pb);
00289         goto redo;
00290     }
00291 
00292     /* find matching stream */
00293     if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
00294           (startcode >= 0x1e0 && startcode <= 0x1ef) ||
00295           (startcode == 0x1bd) || (startcode == 0x1fd)))
00296         goto redo;
00297     if (ppos) {
00298         *ppos = url_ftell(&s->pb) - 4;
00299     }
00300     len = get_be16(&s->pb);
00301     pts =
00302     dts = AV_NOPTS_VALUE;
00303     /* stuffing */
00304     for(;;) {
00305         if (len < 1)
00306             goto error_redo;
00307         c = get_byte(&s->pb);
00308         len--;
00309         /* XXX: for mpeg1, should test only bit 7 */
00310         if (c != 0xff)
00311             break;
00312     }
00313     if ((c & 0xc0) == 0x40) {
00314         /* buffer scale & size */
00315         get_byte(&s->pb);
00316         c = get_byte(&s->pb);
00317         len -= 2;
00318     }
00319     if ((c & 0xe0) == 0x20) {
00320         dts = pts = get_pts(&s->pb, c);
00321         len -= 4;
00322         if (c & 0x10){
00323             dts = get_pts(&s->pb, -1);
00324             len -= 5;
00325         }
00326     } else if ((c & 0xc0) == 0x80) {
00327         /* mpeg 2 PES */
00328 #if 0 /* some streams have this field set for no apparent reason */
00329         if ((c & 0x30) != 0) {
00330             /* Encrypted multiplex not handled */
00331             goto redo;
00332         }
00333 #endif
00334         flags = get_byte(&s->pb);
00335         header_len = get_byte(&s->pb);
00336         len -= 2;
00337         if (header_len > len)
00338             goto error_redo;
00339         len -= header_len;
00340         if (flags & 0x80) {
00341             dts = pts = get_pts(&s->pb, -1);
00342             header_len -= 5;
00343             if (flags & 0x40) {
00344                 dts = get_pts(&s->pb, -1);
00345                 header_len -= 5;
00346             }
00347         }
00348         if (flags & 0x01) { /* PES extension */
00349             pes_ext = get_byte(&s->pb);
00350             header_len--;
00351             if (pes_ext & 0x40) { /* pack header - should be zero in PS */
00352                 goto error_redo;
00353             }
00354             /* Skip PES private data, program packet sequence counter and P-STD buffer */
00355             skip = (pes_ext >> 4) & 0xb;
00356             skip += skip & 0x9;
00357             url_fskip(&s->pb, skip);
00358             header_len -= skip;
00359 
00360             if (pes_ext & 0x01) { /* PES extension 2 */
00361                 ext2_len = get_byte(&s->pb);
00362                 header_len--;
00363                 if ((ext2_len & 0x7f) > 0) {
00364                     id_ext = get_byte(&s->pb);
00365                     if ((id_ext & 0x80) == 0)
00366                         startcode = ((startcode & 0xff) << 8) | id_ext;
00367                     header_len--;
00368                 }
00369             }
00370         }
00371         if(header_len < 0)
00372             goto error_redo;
00373         url_fskip(&s->pb, header_len);
00374     }
00375     else if( c!= 0xf )
00376         goto redo;
00377 
00378     if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {
00379         startcode = get_byte(&s->pb);
00380         len--;
00381         if (startcode >= 0x80 && startcode <= 0xcf) {
00382             /* audio: skip header */
00383             get_byte(&s->pb);
00384             get_byte(&s->pb);
00385             get_byte(&s->pb);
00386             len -= 3;
00387             if (startcode >= 0xb0 && startcode <= 0xbf) {
00388                 /* MLP/TrueHD audio has a 4-byte header */
00389                 get_byte(&s->pb);
00390                 len--;
00391             }
00392         }
00393     }
00394     if(len<0)
00395         goto error_redo;
00396     if(dts != AV_NOPTS_VALUE && ppos){
00397         int i;
00398         for(i=0; i<s->nb_streams; i++){
00399             if(startcode == s->streams[i]->id) {
00400                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
00401             }
00402         }
00403     }
00404 
00405     *pstart_code = startcode;
00406     *ppts = pts;
00407     *pdts = dts;
00408     return len;
00409 }
00410 
00411 static int mpegps_read_packet(AVFormatContext *s,
00412                               AVPacket *pkt)
00413 {
00414     MpegDemuxContext *m = s->priv_data;
00415     AVStream *st;
00416     int len, startcode, i, type, codec_id = 0, es_type;
00417     int64_t pts, dts, dummy_pos = 0; //dummy_pos is needed for the index building to work
00418 
00419  redo:
00420     len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
00421     if (len < 0)
00422         return len;
00423 
00424     /* now find stream */
00425     for(i=0;i<s->nb_streams;i++) {
00426         st = s->streams[i];
00427         if (st->id == startcode)
00428             goto found;
00429     }
00430 
00431     es_type = m->psm_es_type[startcode & 0xff];
00432     if(es_type > 0){
00433         if(es_type == STREAM_TYPE_VIDEO_MPEG1){
00434             codec_id = CODEC_ID_MPEG2VIDEO;
00435             type = CODEC_TYPE_VIDEO;
00436         } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){
00437             codec_id = CODEC_ID_MPEG2VIDEO;
00438             type = CODEC_TYPE_VIDEO;
00439         } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
00440                   es_type == STREAM_TYPE_AUDIO_MPEG2){
00441             codec_id = CODEC_ID_MP3;
00442             type = CODEC_TYPE_AUDIO;
00443         } else if(es_type == STREAM_TYPE_AUDIO_AAC){
00444             codec_id = CODEC_ID_AAC;
00445             type = CODEC_TYPE_AUDIO;
00446         } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){
00447             codec_id = CODEC_ID_MPEG4;
00448             type = CODEC_TYPE_VIDEO;
00449         } else if(es_type == STREAM_TYPE_VIDEO_H264){
00450             codec_id = CODEC_ID_H264;
00451             type = CODEC_TYPE_VIDEO;
00452         } else if(es_type == STREAM_TYPE_AUDIO_AC3){
00453             codec_id = CODEC_ID_AC3;
00454             type = CODEC_TYPE_AUDIO;
00455         } else {
00456             goto skip;
00457         }
00458     } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
00459         static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
00460         unsigned char buf[8];
00461         get_buffer(&s->pb, buf, 8);
00462         url_fseek(&s->pb, -8, SEEK_CUR);
00463         if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
00464             codec_id = CODEC_ID_CAVS;
00465         else
00466             codec_id = CODEC_ID_MPEG2VIDEO;
00467         type = CODEC_TYPE_VIDEO;
00468     } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
00469         type = CODEC_TYPE_AUDIO;
00470         codec_id = m->sofdec > 0 ? CODEC_ID_ADPCM_ADX : CODEC_ID_MP2;
00471     } else if (startcode >= 0x80 && startcode <= 0x87) {
00472         type = CODEC_TYPE_AUDIO;
00473         codec_id = CODEC_ID_AC3;
00474     } else if ((startcode >= 0x88 && startcode <= 0x8f)
00475                ||( startcode >= 0x98 && startcode <= 0x9f)) {
00476         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
00477         type = CODEC_TYPE_AUDIO;
00478         codec_id = CODEC_ID_DTS;
00479     } else if (startcode >= 0xa0 && startcode <= 0xaf) {
00480         type = CODEC_TYPE_AUDIO;
00481         codec_id = CODEC_ID_PCM_S16BE;
00482     } else if (startcode >= 0xb0 && startcode <= 0xbf) {
00483         type = CODEC_TYPE_AUDIO;
00484         codec_id = CODEC_ID_MLP;
00485     } else if (startcode >= 0xc0 && startcode <= 0xcf) {
00486         /* Used for both AC-3 and E-AC-3 in EVOB files */
00487         type = CODEC_TYPE_AUDIO;
00488         codec_id = CODEC_ID_AC3;
00489     } else if (startcode >= 0x20 && startcode <= 0x3f) {
00490         type = CODEC_TYPE_SUBTITLE;
00491         codec_id = CODEC_ID_DVD_SUBTITLE;
00492     } else if (startcode == 0x69 || startcode == 0x49) {
00493         type = CODEC_TYPE_DATA;
00494         codec_id = CODEC_ID_MPEG2VBI;
00495     } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
00496         type = CODEC_TYPE_VIDEO;
00497         codec_id = CODEC_ID_VC1;
00498     } else {
00499     skip:
00500         /* skip packet */
00501         url_fskip(&s->pb, len);
00502         goto redo;
00503     }
00504     /* no stream found: add a new stream */
00505     st = av_new_stream(s, startcode);
00506     if (!st)
00507         goto skip;
00508     st->codec->codec_type = type;
00509     st->codec->codec_id = codec_id;
00510     if (codec_id != CODEC_ID_PCM_S16BE)
00511         st->need_parsing = AVSTREAM_PARSE_FULL;
00512 
00513     /* notify the callback of the change in streams */
00514     if (s->streams_changed) {
00515         s->streams_changed(s->stream_change_data);
00516     }
00517 
00518  found:
00519     if(st->discard >= AVDISCARD_ALL)
00520         goto skip;
00521     if (startcode >= 0xa0 && startcode <= 0xaf) {
00522         int b1, freq;
00523 
00524         /* for LPCM, we just skip the header and consider it is raw
00525            audio data */
00526         if (len <= 3)
00527             goto skip;
00528         get_byte(&s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
00529         b1 = get_byte(&s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
00530         get_byte(&s->pb); /* dynamic range control (0x80 = off) */
00531         len -= 3;
00532         freq = (b1 >> 4) & 3;
00533         st->codec->sample_rate = lpcm_freq_tab[freq];
00534         st->codec->channels = 1 + (b1 & 7);
00535         st->codec->bit_rate = st->codec->channels * st->codec->sample_rate * 2;
00536     }
00537     av_new_packet(pkt, len);
00538     get_buffer(&s->pb, pkt->data, pkt->size);
00539     pkt->pts = pts;
00540     pkt->dts = dts;
00541     pkt->stream_index = st->index;
00542     pkt->pos = dummy_pos;
00543 #if 0
00544     av_log(s, AV_LOG_DEBUG, "%d: pts=%0.3f dts=%0.3f size=%d\n",
00545            pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0, pkt->size);
00546 #endif
00547 
00548     return 0;
00549 }
00550 
00551 static int mpegps_read_close(AVFormatContext *s)
00552 {
00553     return 0;
00554 }
00555 
00556 static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
00557                                int64_t *ppos, int64_t pos_limit)
00558 {
00559     int len, startcode;
00560     int64_t pos, pts, dts;
00561 
00562     pos = *ppos;
00563 #ifdef DEBUG_SEEK
00564     printf("read_dts: pos=0x%"PRIx64" next=%d -> ", pos, find_next);
00565 #endif
00566     url_fseek(&s->pb, pos, SEEK_SET);
00567     for(;;) {
00568         len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
00569         if (len < 0) {
00570 #ifdef DEBUG_SEEK
00571             printf("none (ret=%d)\n", len);
00572 #endif
00573             return AV_NOPTS_VALUE;
00574         }
00575         if (startcode == s->streams[stream_index]->id &&
00576             dts != AV_NOPTS_VALUE) {
00577             break;
00578         }
00579         url_fskip(&s->pb, len);
00580     }
00581 #ifdef DEBUG_SEEK
00582     printf("pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n", pos, dts, dts / 90000.0);
00583 #endif
00584     *ppos = pos;
00585     return dts;
00586 }
00587 
00588 AVInputFormat mpegps_demuxer = {
00589     "mpeg",
00590     "MPEG PS format",
00591     sizeof(MpegDemuxContext),
00592     mpegps_probe,
00593     mpegps_read_header,
00594     mpegps_read_packet,
00595     mpegps_read_close,
00596     NULL, //mpegps_read_seek,
00597     mpegps_read_dts,
00598     .flags = AVFMT_SHOW_IDS,
00599 };