PeerStreamer

/*

 * Metadata demuxer

 * Copyright (c) 2010 Anton Khirnov

 *

 * 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 "ffmeta.h"

#include "internal.h"

static int probe(AVProbeData *p)

{

    if(!memcmp(p->buf, ID_STRING, strlen(ID_STRING)))

        return AVPROBE_SCORE_MAX;

    return 0;

}

static void get_line(ByteIOContext *s, uint8_t *buf, int size)

{

    do {

        uint8_t c;

        int i = 0;

        while ((c = get_byte(s))) {

            if (c == '\\') {

                if (i < size - 1)

                    buf[i++] = c;

                c = get_byte(s);

            } else if (c == '\n')

                break;

            if (i < size - 1)

                buf[i++] = c;

        }

        buf[i] = 0;

    } while (!url_feof(s) && (buf[0] == ';' || buf[0] == '#' || buf[0] == 0));

}

static AVChapter *read_chapter(AVFormatContext *s)

{

    uint8_t line[256];

    int64_t start, end;

    AVRational tb = {1, 1e9};

    get_line(s->pb, line, sizeof(line));

    if (sscanf(line, "TIMEBASE=%d/%d", &tb.num, &tb.den))

        get_line(s->pb, line, sizeof(line));

    if (!sscanf(line, "START=%lld", &start)) {

        av_log(s, AV_LOG_ERROR, "Expected chapter start timestamp, found %s.\n", line);

        start = (s->nb_chapters && s->chapters[s->nb_chapters - 1]->end != AV_NOPTS_VALUE) ?

                 s->chapters[s->nb_chapters - 1]->end : 0;

    } else

        get_line(s->pb, line, sizeof(line));

    if (!sscanf(line, "END=%lld", &end)) {

        av_log(s, AV_LOG_ERROR, "Expected chapter end timestamp, found %s.\n", line);

        end = AV_NOPTS_VALUE;

    }

    return ff_new_chapter(s, s->nb_chapters, tb, start, end, NULL);

}

static uint8_t *unescape(uint8_t *buf, int size)

{

    uint8_t *ret = av_malloc(size + 1);

    uint8_t *p1  = ret, *p2 = buf;

    if (!ret)

        return NULL;

    while (p2 < buf + size) {

        if (*p2 == '\\')

            p2++;

        *p1++ = *p2++;

    }

    *p1 = 0;

    return ret;

}

static int read_tag(uint8_t *line, AVMetadata **m)

{

    uint8_t *key, *value, *p = line;

    /* find first not escaped '=' */

    while (1) {

        if (*p == '=')

            break;

        else if (*p == '\\')

            p++;

        if (*p++)

            continue;

        return 0;

    }

    if (!(key = unescape(line, p - line)))

        return AVERROR(ENOMEM);

    if (!(value = unescape(p + 1, strlen(p + 1)))) {

        av_free(key);

        return AVERROR(ENOMEM);

    }

    av_metadata_set2(m, key, value, AV_METADATA_DONT_STRDUP_KEY | AV_METADATA_DONT_STRDUP_VAL);

    return 0;

}

static int read_header(AVFormatContext *s, AVFormatParameters *ap)

{

    AVMetadata **m = &s->metadata;

    uint8_t line[1024];

    while(!url_feof(s->pb)) {

        get_line(s->pb, line, sizeof(line));

        if (!memcmp(line, ID_STREAM, strlen(ID_STREAM))) {

            AVStream *st = av_new_stream(s, 0);

            if (!st)

                return -1;

            st->codec->codec_type = AVMEDIA_TYPE_DATA;

            st->codec->codec_id   = CODEC_ID_FFMETADATA;

            m = &st->metadata;

        } else if (!memcmp(line, ID_CHAPTER, strlen(ID_CHAPTER))) {

            AVChapter *ch = read_chapter(s);

            if (!ch)

                return -1;

            m = &ch->metadata;

        } else

            read_tag(line, m);

    }

    s->start_time = 0;

    if (s->nb_chapters)

        s->duration = av_rescale_q(s->chapters[s->nb_chapters - 1]->end,

                                   s->chapters[s->nb_chapters - 1]->time_base,

                                   AV_TIME_BASE_Q);

    return 0;

}

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

{

    return AVERROR_EOF;

}

AVInputFormat ff_ffmetadata_demuxer = {

    .name        = "ffmetadata",

    .long_name   = NULL_IF_CONFIG_SMALL("FFmpeg metadata in text format"),

    .read_probe  = probe,

    .read_header = read_header,

    .read_packet = read_packet,

};