?? matroska.c
字號:
} switch (id) { /* one single index entry ('point') */ case MATROSKA_ID_POINTENTRY: if ((res = ebml_read_master(matroska, &id)) < 0) break; /* in the end, we hope to fill one entry with a * timestamp, a file position and a tracknum */ idx.pos = (uint64_t) -1; idx.time = (uint64_t) -1; idx.track = (uint16_t) -1; while (res == 0) { if (!(id = ebml_peek_id(matroska, &matroska->level_up))) { res = AVERROR_IO; break; } else if (matroska->level_up) { matroska->level_up--; break; } switch (id) { /* one single index entry ('point') */ case MATROSKA_ID_CUETIME: { int64_t time; if ((res = ebml_read_uint(matroska, &id, &time)) < 0) break; idx.time = time * matroska->time_scale; break; } /* position in the file + track to which it * belongs */ case MATROSKA_ID_CUETRACKPOSITION: if ((res = ebml_read_master(matroska, &id)) < 0) break; while (res == 0) { if (!(id = ebml_peek_id (matroska, &matroska->level_up))) { res = AVERROR_IO; break; } else if (matroska->level_up) { matroska->level_up--; break; } switch (id) { /* track number */ case MATROSKA_ID_CUETRACK: { uint64_t num; if ((res = ebml_read_uint(matroska, &id, &num)) < 0) break; idx.track = num; break; } /* position in file */ case MATROSKA_ID_CUECLUSTERPOSITION: { uint64_t num; if ((res = ebml_read_uint(matroska, &id, &num)) < 0) break; idx.pos = num; break; } default: av_log(matroska->ctx, AV_LOG_INFO, "Unknown entry 0x%x in " "CuesTrackPositions\n", id); /* fall-through */ case EBML_ID_VOID: res = ebml_read_skip(matroska); break; } if (matroska->level_up) { matroska->level_up--; break; } } break; default: av_log(matroska->ctx, AV_LOG_INFO, "Unknown entry 0x%x in cuespoint " "index\n", id); /* fall-through */ case EBML_ID_VOID: res = ebml_read_skip(matroska); break; } if (matroska->level_up) { matroska->level_up--; break; } } /* so let's see if we got what we wanted */ if (idx.pos != (uint64_t) -1 && idx.time != (uint64_t) -1 && idx.track != (uint16_t) -1) { if (matroska->num_indexes % 32 == 0) { /* re-allocate bigger index */ matroska->index = av_realloc(matroska->index, (matroska->num_indexes + 32) * sizeof(MatroskaDemuxIndex)); } matroska->index[matroska->num_indexes] = idx; matroska->num_indexes++; } break; default: av_log(matroska->ctx, AV_LOG_INFO, "Unknown entry 0x%x in cues header\n", id); /* fall-through */ case EBML_ID_VOID: res = ebml_read_skip(matroska); break; } if (matroska->level_up) { matroska->level_up--; break; } } return res;}static intmatroska_parse_metadata (MatroskaDemuxContext *matroska){ int res = 0; uint32_t id; while (res == 0) { if (!(id = ebml_peek_id(matroska, &matroska->level_up))) { res = AVERROR_IO; break; } else if (matroska->level_up) { matroska->level_up--; break; } switch (id) { /* Hm, this is unsupported... */ default: av_log(matroska->ctx, AV_LOG_INFO, "Unknown entry 0x%x in metadata header\n", id); /* fall-through */ case EBML_ID_VOID: res = ebml_read_skip(matroska); break; } if (matroska->level_up) { matroska->level_up--; break; } } return res;}static intmatroska_parse_seekhead (MatroskaDemuxContext *matroska){ int res = 0; uint32_t id; av_log(matroska->ctx, AV_LOG_DEBUG, "parsing seekhead...\n"); while (res == 0) { if (!(id = ebml_peek_id(matroska, &matroska->level_up))) { res = AVERROR_IO; break; } else if (matroska->level_up) { matroska->level_up--; break; } switch (id) { case MATROSKA_ID_SEEKENTRY: { uint32_t seek_id = 0, peek_id_cache = 0; uint64_t seek_pos = (uint64_t) -1, t; if ((res = ebml_read_master(matroska, &id)) < 0) break; while (res == 0) { if (!(id = ebml_peek_id(matroska, &matroska->level_up))) { res = AVERROR_IO; break; } else if (matroska->level_up) { matroska->level_up--; break; } switch (id) { case MATROSKA_ID_SEEKID: res = ebml_read_uint(matroska, &id, &t); seek_id = t; break; case MATROSKA_ID_SEEKPOSITION: res = ebml_read_uint(matroska, &id, &seek_pos); break; default: av_log(matroska->ctx, AV_LOG_INFO, "Unknown seekhead ID 0x%x\n", id); /* fall-through */ case EBML_ID_VOID: res = ebml_read_skip(matroska); break; } if (matroska->level_up) { matroska->level_up--; break; } } if (!seek_id || seek_pos == (uint64_t) -1) { av_log(matroska->ctx, AV_LOG_INFO, "Incomplete seekhead entry (0x%x/%llu)\n", seek_id, seek_pos); break; } switch (seek_id) { case MATROSKA_ID_CUES: case MATROSKA_ID_TAGS: { uint32_t level_up = matroska->level_up; offset_t before_pos; uint64_t length; MatroskaLevel level; /* remember the peeked ID and the current position */ peek_id_cache = matroska->peek_id; before_pos = url_ftell(&matroska->ctx->pb); /* seek */ if ((res = ebml_read_seek(matroska, seek_pos + matroska->segment_start)) < 0) return res; /* we don't want to lose our seekhead level, so we add * a dummy. This is a crude hack. */ if (matroska->num_levels == EBML_MAX_DEPTH) { av_log(matroska->ctx, AV_LOG_INFO, "Max EBML element depth (%d) reached, " "cannot parse further.\n", EBML_MAX_DEPTH); return AVERROR_UNKNOWN; } level.start = 0; level.length = (uint64_t)-1; matroska->levels[matroska->num_levels] = level; matroska->num_levels++; /* check ID */ if (!(id = ebml_peek_id (matroska, &matroska->level_up))) break; if (id != seek_id) { av_log(matroska->ctx, AV_LOG_INFO, "We looked for ID=0x%x but got " "ID=0x%x (pos=%llu)", seek_id, id, seek_pos + matroska->segment_start); goto finish; } /* read master + parse */ if ((res = ebml_read_master(matroska, &id)) < 0) break; switch (id) { case MATROSKA_ID_CUES: if (!(res = matroska_parse_index(matroska)) || url_feof(&matroska->ctx->pb)) { matroska->index_parsed = 1; res = 0; } break; case MATROSKA_ID_TAGS: if (!(res = matroska_parse_metadata(matroska)) || url_feof(&matroska->ctx->pb)) { matroska->metadata_parsed = 1; res = 0; } break; } if (res < 0) break; finish: /* remove dummy level */ while (matroska->num_levels) { matroska->num_levels--; length = matroska->levels[matroska->num_levels].length; if (length == (uint64_t)-1) break; } /* seek back */ if ((res = ebml_read_seek(matroska, before_pos)) < 0) return res; matroska->peek_id = peek_id_cache; matroska->level_up = level_up; break; } default: av_log(matroska->ctx, AV_LOG_INFO, "Ignoring seekhead entry for ID=0x%x\n", seek_id); break; } break; } default: av_log(matroska->ctx, AV_LOG_INFO, "Unknown seekhead ID 0x%x\n", id); /* fall-through */ case EBML_ID_VOID: res = ebml_read_skip(matroska); break; } if (matroska->level_up) { matroska->level_up--; break; } } return res;}static intmatroska_read_header (AVFormatContext *s, AVFormatParameters *ap){ MatroskaDemuxContext *matroska = s->priv_data; char *doctype; int version, last_level, res = 0; uint32_t id; matroska->ctx = s; /* First read the EBML header. */ doctype = NULL; if ((res = ebml_read_header(matroska, &doctype, &version)) < 0) return res; if ((doctype == NULL) || strcmp(doctype, "matroska")) { av_log(matroska->ctx, AV_LOG_ERROR, "Wrong EBML doctype ('%s' != 'matroska').\n", doctype ? doctype : "(none)"); if (doctype) av_free(doctype); return AVERROR_NOFMT; } av_free(doctype); if (version != 1) { av_log(matroska->ctx, AV_LOG_ERROR, "Matroska demuxer version 1 too old for file version %d\n", version); return AVERROR_NOFMT; } /* The next thing is a segment. */ while (1) { if (!(id = ebml_peek_id(matroska, &last_level))) return AVERROR_IO; if (id == MATROSKA_ID_SEGMENT) break; /* oi! */ av_log(matroska->ctx, AV_LOG_INFO, "Expected a Segment ID (0x%x), but received 0x%x!\n", MATROSKA_ID_SEGMENT, id); if ((res = ebml_read_skip(matroska)) < 0) return res; } /* We now have a Matroska segment. * Seeks are from the beginning of the segment, * after the segment ID/length. */ if ((res = ebml_read_master(matroska, &id)) < 0) return res; matroska->segment_start = url_ftell(&s->pb); matroska->time_scale = 1000000; /* we've found our segment, start reading?? 快捷鍵說明
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