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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 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 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     ByteIOContext *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 = url_ftell(pb);
00077 
00078     syncword = get_be16(pb);
00079     streamid = get_byte(pb);
00080     get_byte(pb);               /* counter not used */
00081     reserved = get_byte(pb);
00082     flags    = get_byte(pb);
00083     length   = get_be16(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 = get_be32(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             = get_be24(pb);
00117             get_byte(pb);
00118             pes_packet_length      = get_be16(pb);
00119             pes_flags              = get_be16(pb);
00120             pes_header_data_length = get_byte(pb);
00121 
00122             if (pes_signal != 1) {
00123                 pva_log(s, AV_LOG_WARNING, "expected signaled PES packet, "
00124                                           "trying to recover\n");
00125                 url_fskip(pb, length - 9);
00126                 if (!read_packet)
00127                     return AVERROR(EIO);
00128                 goto recover;
00129             }
00130 
00131             get_buffer(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     ByteIOContext *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     ByteIOContext *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         url_fseek(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 = url_ftell(pb) + length;
00194             continue;
00195         }
00196         break;
00197     }
00198 
00199     pvactx->continue_pes = 0;
00200     return res;
00201 }
00202 
00203 AVInputFormat 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 };

Generated on Fri Sep 16 2011 17:17:50 for FFmpeg by  doxygen 1.7.1