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ffmpeg / libavformat / tty.c @ f59d8ff8

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/*
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 * Tele-typewriter demuxer
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 * Copyright (c) 2010 Peter Ross <pross@xvid.org>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file
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 * Tele-typewriter demuxer
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 */
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#include "libavutil/intreadwrite.h"
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#include "libavutil/avstring.h"
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#include "avformat.h"
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#include "sauce.h"
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#define LINE_RATE 6000 /* characters per second */
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typedef struct {
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    int chars_per_frame;
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    uint64_t fsize;  /**< file size less metadata buffer */
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} TtyDemuxContext;
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/**
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 * Parse EFI header
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 */
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static int efi_read(AVFormatContext *avctx, uint64_t start_pos)
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{
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    TtyDemuxContext *s = avctx->priv_data;
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    AVIOContext *pb = avctx->pb;
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    char buf[37];
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    int len;
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    avio_seek(pb, start_pos, SEEK_SET);
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    if (avio_r8(pb) != 0x1A)
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        return -1;
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#define GET_EFI_META(name,size) \
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    len = avio_r8(pb); \
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    if (len < 1 || len > size) \
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        return -1; \
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    if (avio_read(pb, buf, size) == size) { \
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        buf[len] = 0; \
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        av_metadata_set2(&avctx->metadata, name, buf, 0); \
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    }
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    GET_EFI_META("filename", 12)
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    GET_EFI_META("title",    36)
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    s->fsize = start_pos;
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    return 0;
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}
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static int read_header(AVFormatContext *avctx,
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                       AVFormatParameters *ap)
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{
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    TtyDemuxContext *s = avctx->priv_data;
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    AVStream *st = av_new_stream(avctx, 0);
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    if (!st)
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        return AVERROR(ENOMEM);
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    st->codec->codec_tag   = 0;
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    st->codec->codec_type  = AVMEDIA_TYPE_VIDEO;
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    st->codec->codec_id    = CODEC_ID_ANSI;
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    if (ap->width)  st->codec->width  = ap->width;
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    if (ap->height) st->codec->height = ap->height;
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    if (!ap->time_base.num) {
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        av_set_pts_info(st, 60, 1, 25);
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    } else {
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        av_set_pts_info(st, 60, ap->time_base.num, ap->time_base.den);
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    }
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    /* simulate tty display speed */
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    s->chars_per_frame = FFMAX(av_q2d(st->time_base) * (ap->sample_rate ? ap->sample_rate : LINE_RATE), 1);
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    if (!url_is_streamed(avctx->pb)) {
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        s->fsize = url_fsize(avctx->pb);
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        st->duration = (s->fsize + s->chars_per_frame - 1) / s->chars_per_frame;
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        if (ff_sauce_read(avctx, &s->fsize, 0, 0) < 0)
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            efi_read(avctx, s->fsize - 51);
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        avio_seek(avctx->pb, 0, SEEK_SET);
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    }
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    return 0;
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}
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static int read_packet(AVFormatContext *avctx, AVPacket *pkt)
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{
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    TtyDemuxContext *s = avctx->priv_data;
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    int n;
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    if (url_feof(avctx->pb))
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        return AVERROR_EOF;
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    n = s->chars_per_frame;
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    if (s->fsize) {
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        // ignore metadata buffer
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        uint64_t p = url_ftell(avctx->pb);
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        if (p + s->chars_per_frame > s->fsize)
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            n = s->fsize - p;
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    }
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    pkt->size = av_get_packet(avctx->pb, pkt, n);
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    if (pkt->size <= 0)
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        return AVERROR(EIO);
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    pkt->flags |= AV_PKT_FLAG_KEY;
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    return 0;
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}
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AVInputFormat ff_tty_demuxer = {
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    .name           = "tty",
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    .long_name      = NULL_IF_CONFIG_SMALL("Tele-typewriter"),
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    .priv_data_size = sizeof(TtyDemuxContext),
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    .read_header    = read_header,
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    .read_packet    = read_packet,
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    .extensions     = "ans,art,asc,diz,ice,nfo,txt,vt",
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};