PeerStreamer

/*

 * TechnoTrend PVA (.pva) demuxer

 * Copyright (c) 2007, 2008 Ivo van Poorten

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "avformat.h"

#include "mpeg.h"

#define PVA_MAX_PAYLOAD_LENGTH  0x17f8

#define PVA_VIDEO_PAYLOAD       0x01

#define PVA_AUDIO_PAYLOAD       0x02

#define PVA_MAGIC               (('A' << 8) + 'V')

typedef struct {

    int continue_pes;

} PVAContext;

static int pva_probe(AVProbeData * pd) {

    unsigned char *buf = pd->buf;

    if (AV_RB16(buf) == PVA_MAGIC && buf[2] && buf[2] < 3 && buf[4] == 0x55)

        return AVPROBE_SCORE_MAX / 2;

    return 0;

}

static int pva_read_header(AVFormatContext *s, AVFormatParameters *ap) {

    AVStream *st;

    if (!(st = av_new_stream(s, 0)))

        return AVERROR(ENOMEM);

    st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

    st->codec->codec_id   = CODEC_ID_MPEG2VIDEO;

    st->need_parsing      = AVSTREAM_PARSE_FULL;

    av_set_pts_info(st, 32, 1, 90000);

    av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);

    if (!(st = av_new_stream(s, 1)))

        return AVERROR(ENOMEM);

    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

    st->codec->codec_id   = CODEC_ID_MP2;

    st->need_parsing      = AVSTREAM_PARSE_FULL;

    av_set_pts_info(st, 33, 1, 90000);

    av_add_index_entry(st, 0, 0, 0, 0, AVINDEX_KEYFRAME);

    /* the parameters will be extracted from the compressed bitstream */

    return 0;

}

#define pva_log if (read_packet) av_log

static int read_part_of_packet(AVFormatContext *s, int64_t *pts,

                               int *len, int *strid, int read_packet) {

    AVIOContext *pb = s->pb;

    PVAContext *pvactx = s->priv_data;

    int syncword, streamid, reserved, flags, length, pts_flag;

    int64_t pva_pts = AV_NOPTS_VALUE, startpos;

recover:

    startpos = avio_tell(pb);

    syncword = avio_rb16(pb);

    streamid = avio_r8(pb);

    avio_r8(pb);               /* counter not used */

    reserved = avio_r8(pb);

    flags    = avio_r8(pb);

    length   = avio_rb16(pb);

    pts_flag = flags & 0x10;

    if (syncword != PVA_MAGIC) {

        pva_log(s, AV_LOG_ERROR, "invalid syncword\n");

        return AVERROR(EIO);

    }

    if (streamid != PVA_VIDEO_PAYLOAD && streamid != PVA_AUDIO_PAYLOAD) {

        pva_log(s, AV_LOG_ERROR, "invalid streamid\n");

        return AVERROR(EIO);

    }

    if (reserved != 0x55) {

        pva_log(s, AV_LOG_WARNING, "expected reserved byte to be 0x55\n");

    }

    if (length > PVA_MAX_PAYLOAD_LENGTH) {

        pva_log(s, AV_LOG_ERROR, "invalid payload length %u\n", length);

        return AVERROR(EIO);

    }

    if (streamid == PVA_VIDEO_PAYLOAD && pts_flag) {

        pva_pts = avio_rb32(pb);

        length -= 4;

    } else if (streamid == PVA_AUDIO_PAYLOAD) {

        /* PVA Audio Packets either start with a signaled PES packet or

         * are a continuation of the previous PES packet. New PES packets

         * always start at the beginning of a PVA Packet, never somewhere in

         * the middle. */

        if (!pvactx->continue_pes) {

            int pes_signal, pes_header_data_length, pes_packet_length,

                pes_flags;

            unsigned char pes_header_data[256];

            pes_signal             = avio_rb24(pb);

            avio_r8(pb);

            pes_packet_length      = avio_rb16(pb);

            pes_flags              = avio_rb16(pb);

            pes_header_data_length = avio_r8(pb);

            if (pes_signal != 1) {

                pva_log(s, AV_LOG_WARNING, "expected signaled PES packet, "

                                          "trying to recover\n");

                avio_seek(pb, length - 9, SEEK_CUR);

                if (!read_packet)

                    return AVERROR(EIO);

                goto recover;

            }

            avio_read(pb, pes_header_data, pes_header_data_length);

            length -= 9 + pes_header_data_length;

            pes_packet_length -= 3 + pes_header_data_length;

            pvactx->continue_pes = pes_packet_length;

            if (pes_flags & 0x80 && (pes_header_data[0] & 0xf0) == 0x20)

                pva_pts = ff_parse_pes_pts(pes_header_data);

        }

        pvactx->continue_pes -= length;

        if (pvactx->continue_pes < 0) {

            pva_log(s, AV_LOG_WARNING, "audio data corruption\n");

            pvactx->continue_pes = 0;

        }

    }

    if (pva_pts != AV_NOPTS_VALUE)

        av_add_index_entry(s->streams[streamid-1], startpos, pva_pts, 0, 0, AVINDEX_KEYFRAME);

    *pts   = pva_pts;

    *len   = length;

    *strid = streamid;

    return 0;

}

static int pva_read_packet(AVFormatContext *s, AVPacket *pkt) {

    AVIOContext *pb = s->pb;

    int64_t pva_pts;

    int ret, length, streamid;

    if (read_part_of_packet(s, &pva_pts, &length, &streamid, 1) < 0 ||

       (ret = av_get_packet(pb, pkt, length)) <= 0)

        return AVERROR(EIO);

    pkt->stream_index = streamid - 1;

    pkt->pts = pva_pts;

    return ret;

}

static int64_t pva_read_timestamp(struct AVFormatContext *s, int stream_index,

                                          int64_t *pos, int64_t pos_limit) {

    AVIOContext *pb = s->pb;

    PVAContext *pvactx = s->priv_data;

    int length, streamid;

    int64_t res = AV_NOPTS_VALUE;

    pos_limit = FFMIN(*pos+PVA_MAX_PAYLOAD_LENGTH*8, (uint64_t)*pos+pos_limit);

    while (*pos < pos_limit) {

        res = AV_NOPTS_VALUE;

        avio_seek(pb, *pos, SEEK_SET);

        pvactx->continue_pes = 0;

        if (read_part_of_packet(s, &res, &length, &streamid, 0)) {

            (*pos)++;

            continue;

        }

        if (streamid - 1 != stream_index || res == AV_NOPTS_VALUE) {

            *pos = avio_tell(pb) + length;

            continue;

        }

        break;

    }

    pvactx->continue_pes = 0;

    return res;

}

AVInputFormat ff_pva_demuxer = {

    "pva",

    NULL_IF_CONFIG_SMALL("TechnoTrend PVA file and stream format"),

    sizeof(PVAContext),

    pva_probe,

    pva_read_header,

    pva_read_packet,

    .read_timestamp = pva_read_timestamp

};