libavformat/pva.c
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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 "internal.h"
00024 #include "mpeg.h"
00025 
00026 #define PVA_MAX_PAYLOAD_LENGTH  0x17f8
00027 #define PVA_VIDEO_PAYLOAD       0x01
00028 #define PVA_AUDIO_PAYLOAD       0x02
00029 #define PVA_MAGIC               (('A' << 8) + 'V')
00030 
00031 typedef struct {
00032     int continue_pes;
00033 } PVAContext;
00034 
00035 static int pva_probe(AVProbeData * pd) {
00036     unsigned char *buf = pd->buf;
00037 
00038     if (AV_RB16(buf) == PVA_MAGIC && buf[2] && buf[2] < 3 && buf[4] == 0x55)
00039         return AVPROBE_SCORE_MAX / 2;
00040 
00041     return 0;
00042 }
00043 
00044 static int pva_read_header(AVFormatContext *s, AVFormatParameters *ap) {
00045     AVStream *st;
00046 
00047     if (!(st = avformat_new_stream(s, NULL)))
00048         return AVERROR(ENOMEM);
00049     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
00050     st->codec->codec_id   = CODEC_ID_MPEG2VIDEO;
00051     st->need_parsing      = AVSTREAM_PARSE_FULL;
00052     avpriv_set_pts_info(st, 32, 1, 90000);
00053     av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);
00054 
00055     if (!(st = avformat_new_stream(s, NULL)))
00056         return AVERROR(ENOMEM);
00057     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
00058     st->codec->codec_id   = CODEC_ID_MP2;
00059     st->need_parsing      = AVSTREAM_PARSE_FULL;
00060     avpriv_set_pts_info(st, 33, 1, 90000);
00061     av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);
00062 
00063     /* the parameters will be extracted from the compressed bitstream */
00064     return 0;
00065 }
00066 
00067 #define pva_log if (read_packet) av_log
00068 
00069 static int read_part_of_packet(AVFormatContext *s, int64_t *pts,
00070                                int *len, int *strid, int read_packet) {
00071     AVIOContext *pb = s->pb;
00072     PVAContext *pvactx = s->priv_data;
00073     int syncword, streamid, reserved, flags, length, pts_flag;
00074     int64_t pva_pts = AV_NOPTS_VALUE, startpos;
00075 
00076 recover:
00077     startpos = avio_tell(pb);
00078 
00079     syncword = avio_rb16(pb);
00080     streamid = avio_r8(pb);
00081     avio_r8(pb);               /* counter not used */
00082     reserved = avio_r8(pb);
00083     flags    = avio_r8(pb);
00084     length   = avio_rb16(pb);
00085 
00086     pts_flag = flags & 0x10;
00087 
00088     if (syncword != PVA_MAGIC) {
00089         pva_log(s, AV_LOG_ERROR, "invalid syncword\n");
00090         return AVERROR(EIO);
00091     }
00092     if (streamid != PVA_VIDEO_PAYLOAD && streamid != PVA_AUDIO_PAYLOAD) {
00093         pva_log(s, AV_LOG_ERROR, "invalid streamid\n");
00094         return AVERROR(EIO);
00095     }
00096     if (reserved != 0x55) {
00097         pva_log(s, AV_LOG_WARNING, "expected reserved byte to be 0x55\n");
00098     }
00099     if (length > PVA_MAX_PAYLOAD_LENGTH) {
00100         pva_log(s, AV_LOG_ERROR, "invalid payload length %u\n", length);
00101         return AVERROR(EIO);
00102     }
00103 
00104     if (streamid == PVA_VIDEO_PAYLOAD && pts_flag) {
00105         pva_pts = avio_rb32(pb);
00106         length -= 4;
00107     } else if (streamid == PVA_AUDIO_PAYLOAD) {
00108         /* PVA Audio Packets either start with a signaled PES packet or
00109          * are a continuation of the previous PES packet. New PES packets
00110          * always start at the beginning of a PVA Packet, never somewhere in
00111          * the middle. */
00112         if (!pvactx->continue_pes) {
00113             int pes_signal, pes_header_data_length, pes_packet_length,
00114                 pes_flags;
00115             unsigned char pes_header_data[256];
00116 
00117             pes_signal             = avio_rb24(pb);
00118             avio_r8(pb);
00119             pes_packet_length      = avio_rb16(pb);
00120             pes_flags              = avio_rb16(pb);
00121             pes_header_data_length = avio_r8(pb);
00122 
00123             if (pes_signal != 1) {
00124                 pva_log(s, AV_LOG_WARNING, "expected signaled PES packet, "
00125                                           "trying to recover\n");
00126                 avio_skip(pb, length - 9);
00127                 if (!read_packet)
00128                     return AVERROR(EIO);
00129                 goto recover;
00130             }
00131 
00132             avio_read(pb, pes_header_data, pes_header_data_length);
00133             length -= 9 + pes_header_data_length;
00134 
00135             pes_packet_length -= 3 + pes_header_data_length;
00136 
00137             pvactx->continue_pes = pes_packet_length;
00138 
00139             if (pes_flags & 0x80 && (pes_header_data[0] & 0xf0) == 0x20)
00140                 pva_pts = ff_parse_pes_pts(pes_header_data);
00141         }
00142 
00143         pvactx->continue_pes -= length;
00144 
00145         if (pvactx->continue_pes < 0) {
00146             pva_log(s, AV_LOG_WARNING, "audio data corruption\n");
00147             pvactx->continue_pes = 0;
00148         }
00149     }
00150 
00151     if (pva_pts != AV_NOPTS_VALUE)
00152         av_add_index_entry(s->streams[streamid-1], startpos, pva_pts, 0, 0, AVINDEX_KEYFRAME);
00153 
00154     *pts   = pva_pts;
00155     *len   = length;
00156     *strid = streamid;
00157     return 0;
00158 }
00159 
00160 static int pva_read_packet(AVFormatContext *s, AVPacket *pkt) {
00161     AVIOContext *pb = s->pb;
00162     int64_t pva_pts;
00163     int ret, length, streamid;
00164 
00165     if (read_part_of_packet(s, &pva_pts, &length, &streamid, 1) < 0 ||
00166        (ret = av_get_packet(pb, pkt, length)) <= 0)
00167         return AVERROR(EIO);
00168 
00169     pkt->stream_index = streamid - 1;
00170     pkt->pts = pva_pts;
00171 
00172     return ret;
00173 }
00174 
00175 static int64_t pva_read_timestamp(struct AVFormatContext *s, int stream_index,
00176                                           int64_t *pos, int64_t pos_limit) {
00177     AVIOContext *pb = s->pb;
00178     PVAContext *pvactx = s->priv_data;
00179     int length, streamid;
00180     int64_t res = AV_NOPTS_VALUE;
00181 
00182     pos_limit = FFMIN(*pos+PVA_MAX_PAYLOAD_LENGTH*8, (uint64_t)*pos+pos_limit);
00183 
00184     while (*pos < pos_limit) {
00185         res = AV_NOPTS_VALUE;
00186         avio_seek(pb, *pos, SEEK_SET);
00187 
00188         pvactx->continue_pes = 0;
00189         if (read_part_of_packet(s, &res, &length, &streamid, 0)) {
00190             (*pos)++;
00191             continue;
00192         }
00193         if (streamid - 1 != stream_index || res == AV_NOPTS_VALUE) {
00194             *pos = avio_tell(pb) + length;
00195             continue;
00196         }
00197         break;
00198     }
00199 
00200     pvactx->continue_pes = 0;
00201     return res;
00202 }
00203 
00204 AVInputFormat ff_pva_demuxer = {
00205     .name           = "pva",
00206     .long_name      = NULL_IF_CONFIG_SMALL("TechnoTrend PVA file and stream format"),
00207     .priv_data_size = sizeof(PVAContext),
00208     .read_probe     = pva_probe,
00209     .read_header    = pva_read_header,
00210     .read_packet    = pva_read_packet,
00211     .read_timestamp = pva_read_timestamp
00212 };