Libav 0.7.1
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00001 /* 00002 * TechnoTrend PVA (.pva) demuxer 00003 * Copyright (c) 2007, 2008 Ivo van Poorten 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 "avformat.h" 00023 #include "mpeg.h" 00024 00025 #define PVA_MAX_PAYLOAD_LENGTH 0x17f8 00026 #define PVA_VIDEO_PAYLOAD 0x01 00027 #define PVA_AUDIO_PAYLOAD 0x02 00028 #define PVA_MAGIC (('A' << 8) + 'V') 00029 00030 typedef struct { 00031 int continue_pes; 00032 } PVAContext; 00033 00034 static int pva_probe(AVProbeData * pd) { 00035 unsigned char *buf = pd->buf; 00036 00037 if (AV_RB16(buf) == PVA_MAGIC && buf[2] && buf[2] < 3 && buf[4] == 0x55) 00038 return AVPROBE_SCORE_MAX / 2; 00039 00040 return 0; 00041 } 00042 00043 static int pva_read_header(AVFormatContext *s, AVFormatParameters *ap) { 00044 AVStream *st; 00045 00046 if (!(st = av_new_stream(s, 0))) 00047 return AVERROR(ENOMEM); 00048 st->codec->codec_type = AVMEDIA_TYPE_VIDEO; 00049 st->codec->codec_id = CODEC_ID_MPEG2VIDEO; 00050 st->need_parsing = AVSTREAM_PARSE_FULL; 00051 av_set_pts_info(st, 32, 1, 90000); 00052 av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME); 00053 00054 if (!(st = av_new_stream(s, 1))) 00055 return AVERROR(ENOMEM); 00056 st->codec->codec_type = AVMEDIA_TYPE_AUDIO; 00057 st->codec->codec_id = CODEC_ID_MP2; 00058 st->need_parsing = AVSTREAM_PARSE_FULL; 00059 av_set_pts_info(st, 33, 1, 90000); 00060 av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME); 00061 00062 /* the parameters will be extracted from the compressed bitstream */ 00063 return 0; 00064 } 00065 00066 #define pva_log if (read_packet) av_log 00067 00068 static int read_part_of_packet(AVFormatContext *s, int64_t *pts, 00069 int *len, int *strid, int read_packet) { 00070 AVIOContext *pb = s->pb; 00071 PVAContext *pvactx = s->priv_data; 00072 int syncword, streamid, reserved, flags, length, pts_flag; 00073 int64_t pva_pts = AV_NOPTS_VALUE, startpos; 00074 00075 recover: 00076 startpos = avio_tell(pb); 00077 00078 syncword = avio_rb16(pb); 00079 streamid = avio_r8(pb); 00080 avio_r8(pb); /* counter not used */ 00081 reserved = avio_r8(pb); 00082 flags = avio_r8(pb); 00083 length = avio_rb16(pb); 00084 00085 pts_flag = flags & 0x10; 00086 00087 if (syncword != PVA_MAGIC) { 00088 pva_log(s, AV_LOG_ERROR, "invalid syncword\n"); 00089 return AVERROR(EIO); 00090 } 00091 if (streamid != PVA_VIDEO_PAYLOAD && streamid != PVA_AUDIO_PAYLOAD) { 00092 pva_log(s, AV_LOG_ERROR, "invalid streamid\n"); 00093 return AVERROR(EIO); 00094 } 00095 if (reserved != 0x55) { 00096 pva_log(s, AV_LOG_WARNING, "expected reserved byte to be 0x55\n"); 00097 } 00098 if (length > PVA_MAX_PAYLOAD_LENGTH) { 00099 pva_log(s, AV_LOG_ERROR, "invalid payload length %u\n", length); 00100 return AVERROR(EIO); 00101 } 00102 00103 if (streamid == PVA_VIDEO_PAYLOAD && pts_flag) { 00104 pva_pts = avio_rb32(pb); 00105 length -= 4; 00106 } else if (streamid == PVA_AUDIO_PAYLOAD) { 00107 /* PVA Audio Packets either start with a signaled PES packet or 00108 * are a continuation of the previous PES packet. New PES packets 00109 * always start at the beginning of a PVA Packet, never somewhere in 00110 * the middle. */ 00111 if (!pvactx->continue_pes) { 00112 int pes_signal, pes_header_data_length, pes_packet_length, 00113 pes_flags; 00114 unsigned char pes_header_data[256]; 00115 00116 pes_signal = avio_rb24(pb); 00117 avio_r8(pb); 00118 pes_packet_length = avio_rb16(pb); 00119 pes_flags = avio_rb16(pb); 00120 pes_header_data_length = avio_r8(pb); 00121 00122 if (pes_signal != 1) { 00123 pva_log(s, AV_LOG_WARNING, "expected signaled PES packet, " 00124 "trying to recover\n"); 00125 avio_skip(pb, length - 9); 00126 if (!read_packet) 00127 return AVERROR(EIO); 00128 goto recover; 00129 } 00130 00131 avio_read(pb, pes_header_data, pes_header_data_length); 00132 length -= 9 + pes_header_data_length; 00133 00134 pes_packet_length -= 3 + pes_header_data_length; 00135 00136 pvactx->continue_pes = pes_packet_length; 00137 00138 if (pes_flags & 0x80 && (pes_header_data[0] & 0xf0) == 0x20) 00139 pva_pts = ff_parse_pes_pts(pes_header_data); 00140 } 00141 00142 pvactx->continue_pes -= length; 00143 00144 if (pvactx->continue_pes < 0) { 00145 pva_log(s, AV_LOG_WARNING, "audio data corruption\n"); 00146 pvactx->continue_pes = 0; 00147 } 00148 } 00149 00150 if (pva_pts != AV_NOPTS_VALUE) 00151 av_add_index_entry(s->streams[streamid-1], startpos, pva_pts, 0, 0, AVINDEX_KEYFRAME); 00152 00153 *pts = pva_pts; 00154 *len = length; 00155 *strid = streamid; 00156 return 0; 00157 } 00158 00159 static int pva_read_packet(AVFormatContext *s, AVPacket *pkt) { 00160 AVIOContext *pb = s->pb; 00161 int64_t pva_pts; 00162 int ret, length, streamid; 00163 00164 if (read_part_of_packet(s, &pva_pts, &length, &streamid, 1) < 0 || 00165 (ret = av_get_packet(pb, pkt, length)) <= 0) 00166 return AVERROR(EIO); 00167 00168 pkt->stream_index = streamid - 1; 00169 pkt->pts = pva_pts; 00170 00171 return ret; 00172 } 00173 00174 static int64_t pva_read_timestamp(struct AVFormatContext *s, int stream_index, 00175 int64_t *pos, int64_t pos_limit) { 00176 AVIOContext *pb = s->pb; 00177 PVAContext *pvactx = s->priv_data; 00178 int length, streamid; 00179 int64_t res = AV_NOPTS_VALUE; 00180 00181 pos_limit = FFMIN(*pos+PVA_MAX_PAYLOAD_LENGTH*8, (uint64_t)*pos+pos_limit); 00182 00183 while (*pos < pos_limit) { 00184 res = AV_NOPTS_VALUE; 00185 avio_seek(pb, *pos, SEEK_SET); 00186 00187 pvactx->continue_pes = 0; 00188 if (read_part_of_packet(s, &res, &length, &streamid, 0)) { 00189 (*pos)++; 00190 continue; 00191 } 00192 if (streamid - 1 != stream_index || res == AV_NOPTS_VALUE) { 00193 *pos = avio_tell(pb) + length; 00194 continue; 00195 } 00196 break; 00197 } 00198 00199 pvactx->continue_pes = 0; 00200 return res; 00201 } 00202 00203 AVInputFormat ff_pva_demuxer = { 00204 "pva", 00205 NULL_IF_CONFIG_SMALL("TechnoTrend PVA file and stream format"), 00206 sizeof(PVAContext), 00207 pva_probe, 00208 pva_read_header, 00209 pva_read_packet, 00210 .read_timestamp = pva_read_timestamp 00211 };