PeerStreamer

/*

 * Core Audio Format demuxer

 * Copyright (c) 2007 Justin Ruggles

 * Copyright (c) 2009 Peter Ross

 *

 * 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 libavformat/cafdec.c

 * Core Audio Format demuxer

 */

#include "avformat.h"

#include "riff.h"

#include "isom.h"

#include "libavutil/intreadwrite.h"

#include "caf.h"

typedef struct {

    int bytes_per_packet;           ///< bytes in a packet, or 0 if variable

    int frames_per_packet;          ///< frames in a packet, or 0 if variable

    int64_t num_bytes;              ///< total number of bytes in stream

    int64_t packet_cnt;             ///< packet counter

    int64_t frame_cnt;              ///< frame counter

    int64_t data_start;             ///< data start position, in bytes

    int64_t data_size;              ///< raw data size, in bytes

} CaffContext;

static int probe(AVProbeData *p)

{

    if (AV_RB32(p->buf) == MKBETAG('c','a','f','f') && AV_RB16(&p->buf[4]) == 1)

        return AVPROBE_SCORE_MAX;

    return 0;

}

/** Read audio description chunk */

static int read_desc_chunk(AVFormatContext *s)

{

    ByteIOContext *pb = s->pb;

    CaffContext *caf  = s->priv_data;

    AVStream *st;

    int flags;

    /* new audio stream */

    st = av_new_stream(s, 0);

    if (!st)

        return AVERROR(ENOMEM);

    /* parse format description */

    st->codec->codec_type  = AVMEDIA_TYPE_AUDIO;

    st->codec->sample_rate = av_int2dbl(get_be64(pb));

    st->codec->codec_tag   = get_be32(pb);

    flags = get_be32(pb);

    caf->bytes_per_packet  = get_be32(pb);

    st->codec->block_align = caf->bytes_per_packet;

    caf->frames_per_packet = get_be32(pb);

    st->codec->channels    = get_be32(pb);

    st->codec->bits_per_coded_sample = get_be32(pb);

    /* calculate bit rate for constant size packets */

    if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {

        st->codec->bit_rate = (uint64_t)st->codec->sample_rate * (uint64_t)caf->bytes_per_packet * 8

                              / (uint64_t)caf->frames_per_packet;

    } else {

        st->codec->bit_rate = 0;

    }

    /* determine codec */

    if (st->codec->codec_tag == MKBETAG('l','p','c','m'))

        st->codec->codec_id = ff_mov_get_lpcm_codec_id(st->codec->bits_per_coded_sample, (flags ^ 0x2) | 0x4);

    else

        st->codec->codec_id = ff_codec_get_id(ff_codec_caf_tags, st->codec->codec_tag);

    return 0;

}

/** Read magic cookie chunk */

static int read_kuki_chunk(AVFormatContext *s, int64_t size)

{

    ByteIOContext *pb = s->pb;

    AVStream *st      = s->streams[0];

    if (size < 0 || size > INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE)

        return -1;

    if (st->codec->codec_id == CODEC_ID_AAC) {

        /* The magic cookie format for AAC is an mp4 esds atom.

           The lavc AAC decoder requires the data from the codec specific

           description as extradata input. */

        int strt, skip;

        MOVAtom atom;

        strt = url_ftell(pb);

        ff_mov_read_esds(s, pb, atom);

        skip = size - (url_ftell(pb) - strt);

        if (skip < 0 || !st->codec->extradata ||

            st->codec->codec_id != CODEC_ID_AAC) {

            av_log(s, AV_LOG_ERROR, "invalid AAC magic cookie\n");

            return AVERROR_INVALIDDATA;

        }

        url_fskip(pb, skip);

    } else {

        st->codec->extradata = av_mallocz(size + FF_INPUT_BUFFER_PADDING_SIZE);

        if (!st->codec->extradata)

            return AVERROR(ENOMEM);

        get_buffer(pb, st->codec->extradata, size);

        st->codec->extradata_size = size;

    }

    return 0;

}

/** Read packet table chunk */

static int read_pakt_chunk(AVFormatContext *s, int64_t size)

{

    ByteIOContext *pb = s->pb;

    AVStream *st      = s->streams[0];

    CaffContext *caf  = s->priv_data;

    int64_t pos = 0, ccount;

    int num_packets, i;

    ccount = url_ftell(pb);

    num_packets = get_be64(pb);

    if (num_packets < 0 || INT32_MAX / sizeof(AVIndexEntry) < num_packets)

        return AVERROR_INVALIDDATA;

    st->nb_frames  = get_be64(pb); /* valid frames */

    st->nb_frames += get_be32(pb); /* priming frames */

    st->nb_frames += get_be32(pb); /* remainder frames */

    st->duration = 0;

    for (i = 0; i < num_packets; i++) {

        av_add_index_entry(s->streams[0], pos, st->duration, 0, 0, AVINDEX_KEYFRAME);

        pos += caf->bytes_per_packet ? caf->bytes_per_packet : ff_mp4_read_descr_len(pb);

        st->duration += caf->frames_per_packet ? caf->frames_per_packet : ff_mp4_read_descr_len(pb);

    }

    if (url_ftell(pb) - ccount != size) {

        av_log(s, AV_LOG_ERROR, "error reading packet table\n");

        return -1;

    }

    caf->num_bytes = pos;

    return 0;

}

/** Read information chunk */

static void read_info_chunk(AVFormatContext *s, int64_t size)

{

    ByteIOContext *pb = s->pb;

    unsigned int i;

    unsigned int nb_entries = get_be32(pb);

    for (i = 0; i < nb_entries; i++) {

        char key[32];

        char value[1024];

        get_strz(pb, key, sizeof(key));

        get_strz(pb, value, sizeof(value));

        av_metadata_set(&s->metadata, key, value);

    }

}

static int read_header(AVFormatContext *s,

                       AVFormatParameters *ap)

{

    ByteIOContext *pb = s->pb;

    CaffContext *caf  = s->priv_data;

    AVStream *st;

    uint32_t tag = 0;

    int found_data, ret;

    int64_t size;

    url_fskip(pb, 8); /* magic, version, file flags */

    /* audio description chunk */

    if (get_be32(pb) != MKBETAG('d','e','s','c')) {

        av_log(s, AV_LOG_ERROR, "desc chunk not present\n");

        return AVERROR_INVALIDDATA;

    }

    size = get_be64(pb);

    if (size != 32)

        return AVERROR_INVALIDDATA;

    ret = read_desc_chunk(s);

    if (ret)

        return ret;

    st = s->streams[0];

    /* parse each chunk */

    found_data = 0;

    while (!url_feof(pb)) {

        /* stop at data chunk if seeking is not supported or

           data chunk size is unknown */

        if (found_data && (caf->data_size < 0 || url_is_streamed(pb)))

            break;

        tag  = get_be32(pb);

        size = get_be64(pb);

        if (url_feof(pb))

            break;

        switch (tag) {

        case MKBETAG('d','a','t','a'):

            url_fskip(pb, 4); /* edit count */

            caf->data_start = url_ftell(pb);

            caf->data_size  = size < 0 ? -1 : size - 4;

            if (caf->data_size > 0 && !url_is_streamed(pb))

                url_fskip(pb, caf->data_size);

            found_data = 1;

            break;

        /* magic cookie chunk */

        case MKBETAG('k','u','k','i'):

            if (read_kuki_chunk(s, size))

                return AVERROR_INVALIDDATA;

            break;

        /* packet table chunk */

        case MKBETAG('p','a','k','t'):

            if (read_pakt_chunk(s, size))

                return AVERROR_INVALIDDATA;

            break;

        case MKBETAG('i','n','f','o'):

            read_info_chunk(s, size);

            break;

        default:

#define _(x) ((x) >= ' ' ? (x) : ' ')

            av_log(s, AV_LOG_WARNING, "skipping CAF chunk: %08X (%c%c%c%c)\n",

                tag, _(tag>>24), _((tag>>16)&0xFF), _((tag>>8)&0xFF), _(tag&0xFF));

#undef _

        case MKBETAG('f','r','e','e'):

            if (size < 0)

                return AVERROR_INVALIDDATA;

            url_fskip(pb, size);

            break;

        }

    }

    if (!found_data)

        return AVERROR_INVALIDDATA;

    if (caf->bytes_per_packet > 0 && caf->frames_per_packet > 0) {

        if (caf->data_size > 0)

            st->nb_frames = (caf->data_size / caf->bytes_per_packet) * caf->frames_per_packet;

    } else if (st->nb_index_entries) {

        st->codec->bit_rate = st->codec->sample_rate * caf->data_size * 8 /

                              st->duration;

    } else {

        av_log(s, AV_LOG_ERROR, "Missing packet table. It is required when "

                                "block size or frame size are variable.\n");

        return AVERROR_INVALIDDATA;

    }

    s->file_size = url_fsize(pb);

    s->file_size = FFMAX(0, s->file_size);

    av_set_pts_info(st, 64, 1, st->codec->sample_rate);

    st->start_time = 0;

    /* position the stream at the start of data */

    if (caf->data_size >= 0)

        url_fseek(pb, caf->data_start, SEEK_SET);

    return 0;

}

#define CAF_MAX_PKT_SIZE 4096

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

{

    ByteIOContext *pb = s->pb;

    AVStream *st      = s->streams[0];

    CaffContext *caf  = s->priv_data;

    int res, pkt_size = 0, pkt_frames = 0;

    int64_t left      = CAF_MAX_PKT_SIZE;

    if (url_feof(pb))

        return AVERROR(EIO);

    /* don't read past end of data chunk */

    if (caf->data_size > 0) {

        left = (caf->data_start + caf->data_size) - url_ftell(pb);

        if (left <= 0)

            return AVERROR(EIO);

    }

    pkt_frames = caf->frames_per_packet;

    pkt_size   = caf->bytes_per_packet;

    if (pkt_size > 0 && pkt_frames == 1) {

        pkt_size   = (CAF_MAX_PKT_SIZE / pkt_size) * pkt_size;

        pkt_size   = FFMIN(pkt_size, left);

        pkt_frames = pkt_size / caf->bytes_per_packet;

    } else if (st->nb_index_entries) {

        if (caf->packet_cnt < st->nb_index_entries - 1) {

            pkt_size   = st->index_entries[caf->packet_cnt + 1].pos       - st->index_entries[caf->packet_cnt].pos;

            pkt_frames = st->index_entries[caf->packet_cnt + 1].timestamp - st->index_entries[caf->packet_cnt].timestamp;

        } else if (caf->packet_cnt == st->nb_index_entries - 1) {

            pkt_size   = caf->num_bytes - st->index_entries[caf->packet_cnt].pos;

            pkt_frames = st->duration   - st->index_entries[caf->packet_cnt].timestamp;

        } else {

            return AVERROR(EIO);

        }

    }

    if (pkt_size == 0 || pkt_frames == 0 || pkt_size > left)

        return AVERROR(EIO);

    res = av_get_packet(pb, pkt, pkt_size);

    if (res < 0)

        return res;

    pkt->size           = res;

    pkt->stream_index   = 0;

    pkt->dts = pkt->pts = caf->frame_cnt;

    caf->packet_cnt++;

    caf->frame_cnt += pkt_frames;

    return 0;

}

static int read_seek(AVFormatContext *s, int stream_index,

                     int64_t timestamp, int flags)

{

    AVStream *st = s->streams[0];

    CaffContext *caf = s->priv_data;

    int64_t pos;

    timestamp = FFMAX(timestamp, 0);

    if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {

        /* calculate new byte position based on target frame position */

        pos = caf->bytes_per_packet * timestamp / caf->frames_per_packet;

        if (caf->data_size > 0)

            pos = FFMIN(pos, caf->data_size);

        caf->packet_cnt = pos / caf->bytes_per_packet;

        caf->frame_cnt  = caf->frames_per_packet * caf->packet_cnt;

    } else if (st->nb_index_entries) {

        caf->packet_cnt = av_index_search_timestamp(st, timestamp, flags);

        caf->frame_cnt  = st->index_entries[caf->packet_cnt].timestamp;

        pos             = st->index_entries[caf->packet_cnt].pos;

    } else {

        return -1;

    }

    url_fseek(s->pb, pos + caf->data_start, SEEK_SET);

    return 0;

}

AVInputFormat caf_demuxer = {

    "caf",

    NULL_IF_CONFIG_SMALL("Apple Core Audio Format"),

    sizeof(CaffContext),

    probe,

    read_header,

    read_packet,

    NULL,

    read_seek,

    .codec_tag = (const AVCodecTag*[]){ff_codec_caf_tags, 0},

};