PeerStreamer

/*

 * Tele-typewriter demuxer

 * Copyright (c) 2010 Peter Ross <pross@xvid.org>

 *

 * 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

 */

/**

 * @file

 * Tele-typewriter demuxer

 */

#include "libavutil/intreadwrite.h"

#include "libavutil/avstring.h"

#include "avformat.h"

#include "sauce.h"

#define LINE_RATE 6000 /* characters per second */

typedef struct {

    int chars_per_frame;

    uint64_t fsize;  /**< file size less metadata buffer */

} TtyDemuxContext;

/**

 * Parse EFI header

 */

static int efi_read(AVFormatContext *avctx, uint64_t start_pos)

{

    TtyDemuxContext *s = avctx->priv_data;

    AVIOContext *pb = avctx->pb;

    char buf[37];

    int len;

    avio_seek(pb, start_pos, SEEK_SET);

    if (avio_r8(pb) != 0x1A)

        return -1;

#define GET_EFI_META(name,size) \

    len = avio_r8(pb); \

    if (len < 1 || len > size) \

        return -1; \

    if (avio_read(pb, buf, size) == size) { \

        buf[len] = 0; \

        av_metadata_set2(&avctx->metadata, name, buf, 0); \

    }

    GET_EFI_META("filename", 12)

    GET_EFI_META("title",    36)

    s->fsize = start_pos;

    return 0;

}

static int read_header(AVFormatContext *avctx,

                       AVFormatParameters *ap)

{

    TtyDemuxContext *s = avctx->priv_data;

    AVStream *st = av_new_stream(avctx, 0);

    if (!st)

        return AVERROR(ENOMEM);

    st->codec->codec_tag   = 0;

    st->codec->codec_type  = AVMEDIA_TYPE_VIDEO;

    st->codec->codec_id    = CODEC_ID_ANSI;

    if (ap->width)  st->codec->width  = ap->width;

    if (ap->height) st->codec->height = ap->height;

    if (!ap->time_base.num) {

        av_set_pts_info(st, 60, 1, 25);

    } else {

        av_set_pts_info(st, 60, ap->time_base.num, ap->time_base.den);

    }

    /* simulate tty display speed */

    s->chars_per_frame = FFMAX(av_q2d(st->time_base) * (ap->sample_rate ? ap->sample_rate : LINE_RATE), 1);

    if (!url_is_streamed(avctx->pb)) {

        s->fsize = url_fsize(avctx->pb);

        st->duration = (s->fsize + s->chars_per_frame - 1) / s->chars_per_frame;

        if (ff_sauce_read(avctx, &s->fsize, 0, 0) < 0)

            efi_read(avctx, s->fsize - 51);

        avio_seek(avctx->pb, 0, SEEK_SET);

    }

    return 0;

}

static int read_packet(AVFormatContext *avctx, AVPacket *pkt)

{

    TtyDemuxContext *s = avctx->priv_data;

    int n;

    if (url_feof(avctx->pb))

        return AVERROR_EOF;

    n = s->chars_per_frame;

    if (s->fsize) {

        // ignore metadata buffer

        uint64_t p = avio_tell(avctx->pb);

        if (p + s->chars_per_frame > s->fsize)

            n = s->fsize - p;

    }

    pkt->size = av_get_packet(avctx->pb, pkt, n);

    if (pkt->size <= 0)

        return AVERROR(EIO);

    pkt->flags |= AV_PKT_FLAG_KEY;

    return 0;

}

AVInputFormat ff_tty_demuxer = {

    .name           = "tty",

    .long_name      = NULL_IF_CONFIG_SMALL("Tele-typewriter"),

    .priv_data_size = sizeof(TtyDemuxContext),

    .read_header    = read_header,

    .read_packet    = read_packet,

    .extensions     = "ans,art,asc,diz,ice,nfo,txt,vt",

};