yading@11: /*
yading@11:  * NC camera feed demuxer
yading@11:  * Copyright (c) 2009  Nicolas Martin (martinic at iro dot umontreal dot ca)
yading@11:  *                     Edouard Auvinet
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "libavutil/intreadwrite.h"
yading@11: #include "avformat.h"
yading@11: #include "internal.h"
yading@11: 
yading@11: #define NC_VIDEO_FLAG 0x1A5
yading@11: 
yading@11: static int nc_probe(AVProbeData *probe_packet)
yading@11: {
yading@11:     int size;
yading@11: 
yading@11:     if (AV_RB32(probe_packet->buf) != NC_VIDEO_FLAG)
yading@11:         return 0;
yading@11: 
yading@11:     size = AV_RL16(probe_packet->buf + 5);
yading@11: 
yading@11:     if (size + 20 > probe_packet->buf_size)
yading@11:         return AVPROBE_SCORE_MAX/4;
yading@11: 
yading@11:     if (AV_RB32(probe_packet->buf+16+size) == NC_VIDEO_FLAG)
yading@11:         return AVPROBE_SCORE_MAX;
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int nc_read_header(AVFormatContext *s)
yading@11: {
yading@11:     AVStream *st = avformat_new_stream(s, NULL);
yading@11: 
yading@11:     if (!st)
yading@11:         return AVERROR(ENOMEM);
yading@11: 
yading@11:     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
yading@11:     st->codec->codec_id   = AV_CODEC_ID_MPEG4;
yading@11:     st->need_parsing      = AVSTREAM_PARSE_FULL;
yading@11: 
yading@11:     avpriv_set_pts_info(st, 64, 1, 100);
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
yading@11: {
yading@11:     int size;
yading@11:     int ret;
yading@11: 
yading@11:     uint32_t state=-1;
yading@11:     while (state != NC_VIDEO_FLAG) {
yading@11:         if (url_feof(s->pb))
yading@11:             return AVERROR(EIO);
yading@11:         state = (state<<8) + avio_r8(s->pb);
yading@11:     }
yading@11: 
yading@11:     avio_r8(s->pb);
yading@11:     size = avio_rl16(s->pb);
yading@11:     avio_skip(s->pb, 9);
yading@11: 
yading@11:     if (size == 0) {
yading@11:         av_log(s, AV_LOG_DEBUG, "Next packet size is zero\n");
yading@11:         return AVERROR(EAGAIN);
yading@11:     }
yading@11: 
yading@11:     ret = av_get_packet(s->pb, pkt, size);
yading@11:     if (ret != size) {
yading@11:         if (ret > 0) av_free_packet(pkt);
yading@11:         return AVERROR(EIO);
yading@11:     }
yading@11: 
yading@11:     pkt->stream_index = 0;
yading@11:     return size;
yading@11: }
yading@11: 
yading@11: AVInputFormat ff_nc_demuxer = {
yading@11:     .name           = "nc",
yading@11:     .long_name      = NULL_IF_CONFIG_SMALL("NC camera feed"),
yading@11:     .read_probe     = nc_probe,
yading@11:     .read_header    = nc_read_header,
yading@11:     .read_packet    = nc_read_packet,
yading@11:     .extensions     = "v",
yading@11: };