root/libavformat/hca.c

DEFINITIONS

1. hca_probe
2. hca_read_header
3. hca_read_packet

/*
 * HCA demuxer
 * Copyright (c) 2020 Paul B Mahol
 *
 * 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 "libavutil/intreadwrite.h"
#include "libavcodec/bytestream.h"

#include "avformat.h"
#include "internal.h"

static int hca_probe(const AVProbeData *p)
{
    if (AV_RL32(p->buf) != MKTAG('H', 'C', 'A', 0))
        return 0;

    if (AV_RL32(p->buf + 8) != MKTAG('f', 'm', 't', 0))
        return 0;

    return AVPROBE_SCORE_MAX / 3;
}

static int hca_read_header(AVFormatContext *s)
{
    AVCodecParameters *par;
    GetByteContext gb;
    AVIOContext *pb = s->pb;
    AVStream *st;
    uint32_t chunk;
    uint16_t version;
    uint32_t block_count;
    uint16_t block_size;
    int ret;

    avio_skip(pb, 4);
    version = avio_rb16(pb);

    s->internal->data_offset = avio_rb16(pb);
    if (s->internal->data_offset <= 8)
        return AVERROR_INVALIDDATA;

    st = avformat_new_stream(s, NULL);
    if (!st)
        return AVERROR(ENOMEM);

    par = st->codecpar;
    ret = ff_alloc_extradata(par, s->internal->data_offset);
    if (ret < 0)
        return ret;

    ret = avio_read(pb, par->extradata + 8, par->extradata_size - 8);
    if (ret < par->extradata_size - 8)
        return AVERROR(EIO);
    AV_WL32(par->extradata, MKTAG('H', 'C', 'A', 0));
    AV_WB16(par->extradata + 4, version);
    AV_WB16(par->extradata + 6, s->internal->data_offset);

    bytestream2_init(&gb, par->extradata + 8, par->extradata_size - 8);

    if (bytestream2_get_le32(&gb) != MKTAG('f', 'm', 't', 0))
        return AVERROR_INVALIDDATA;

    par->codec_type  = AVMEDIA_TYPE_AUDIO;
    par->codec_id    = AV_CODEC_ID_HCA;
    par->codec_tag   = 0;
    par->channels    = bytestream2_get_byte(&gb);
    par->sample_rate = bytestream2_get_be24(&gb);
    block_count      = bytestream2_get_be32(&gb);
    bytestream2_skip(&gb, 4);
    chunk = bytestream2_get_le32(&gb);
    if (chunk == MKTAG('c', 'o', 'm', 'p')) {
        block_size = bytestream2_get_be16(&gb);
    } else if (chunk == MKTAG('d', 'e', 'c', 0)) {
        block_size = bytestream2_get_be16(&gb);
    } else {
        return AVERROR_INVALIDDATA;
    }

    if (block_size < 8)
        return AVERROR_INVALIDDATA;
    par->block_align = block_size;
    st->duration = 1024 * block_count;

    avio_seek(pb, s->internal->data_offset, SEEK_SET);
    avpriv_set_pts_info(st, 64, 1, par->sample_rate);

    return 0;
}

static int hca_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    AVCodecParameters *par = s->streams[0]->codecpar;
    int ret;

    ret = av_get_packet(s->pb, pkt, par->block_align);
    pkt->duration = 1024;
    return ret;
}

AVInputFormat ff_hca_demuxer = {
    .name           = "hca",
    .long_name      = NULL_IF_CONFIG_SMALL("CRI HCA"),
    .read_probe     = hca_probe,
    .read_header    = hca_read_header,
    .read_packet    = hca_read_packet,
    .extensions     = "hca",
    .flags          = AVFMT_GENERIC_INDEX,
};