PeerStreamer

/*

 * Musepack demuxer

 * Copyright (c) 2006 Konstantin Shishkov

 *

 * 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 "libavcodec/get_bits.h"

#include "avformat.h"

#include "apetag.h"

#include "id3v1.h"

#define MPC_FRAMESIZE  1152

#define DELAY_FRAMES   32

static const int mpc_rate[4] = { 44100, 48000, 37800, 32000 };

typedef struct {

    int64_t pos;

    int size, skip;

}MPCFrame;

typedef struct {

    int ver;

    uint32_t curframe, lastframe;

    uint32_t fcount;

    MPCFrame *frames;

    int curbits;

    int frames_noted;

} MPCContext;

static int mpc_probe(AVProbeData *p)

{

    const uint8_t *d = p->buf;

    if (d[0] == 'M' && d[1] == 'P' && d[2] == '+' && (d[3] == 0x17 || d[3] == 0x7))

        return AVPROBE_SCORE_MAX;

    return 0;

}

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

{

    MPCContext *c = s->priv_data;

    AVStream *st;

    if(avio_rl24(s->pb) != MKTAG('M', 'P', '+', 0)){

        av_log(s, AV_LOG_ERROR, "Not a Musepack file\n");

        return -1;

    }

    c->ver = avio_r8(s->pb);

    if(c->ver != 0x07 && c->ver != 0x17){

        av_log(s, AV_LOG_ERROR, "Can demux Musepack SV7, got version %02X\n", c->ver);

        return -1;

    }

    c->fcount = avio_rl32(s->pb);

    if((int64_t)c->fcount * sizeof(MPCFrame) >= UINT_MAX){

        av_log(s, AV_LOG_ERROR, "Too many frames, seeking is not possible\n");

        return -1;

    }

    c->frames = av_malloc(c->fcount * sizeof(MPCFrame));

    c->curframe = 0;

    c->lastframe = -1;

    c->curbits = 8;

    c->frames_noted = 0;

    st = av_new_stream(s, 0);

    if (!st)

        return AVERROR(ENOMEM);

    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

    st->codec->codec_id = CODEC_ID_MUSEPACK7;

    st->codec->channels = 2;

    st->codec->bits_per_coded_sample = 16;

    st->codec->extradata_size = 16;

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

    avio_read(s->pb, st->codec->extradata, 16);

    st->codec->sample_rate = mpc_rate[st->codec->extradata[2] & 3];

    av_set_pts_info(st, 32, MPC_FRAMESIZE, st->codec->sample_rate);

    /* scan for seekpoints */

    st->start_time = 0;

    st->duration = c->fcount;

    /* try to read APE tags */

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

        int64_t pos = avio_tell(s->pb);

        ff_ape_parse_tag(s);

        if (!av_metadata_get(s->metadata, "", NULL, AV_METADATA_IGNORE_SUFFIX))

            ff_id3v1_read(s);

        avio_seek(s->pb, pos, SEEK_SET);

    }

    return 0;

}

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

{

    MPCContext *c = s->priv_data;

    int ret, size, size2, curbits, cur = c->curframe;

    int64_t tmp, pos;

    if (c->curframe >= c->fcount)

        return -1;

    if(c->curframe != c->lastframe + 1){

        avio_seek(s->pb, c->frames[c->curframe].pos, SEEK_SET);

        c->curbits = c->frames[c->curframe].skip;

    }

    c->lastframe = c->curframe;

    c->curframe++;

    curbits = c->curbits;

    pos = avio_tell(s->pb);

    tmp = avio_rl32(s->pb);

    if(curbits <= 12){

        size2 = (tmp >> (12 - curbits)) & 0xFFFFF;

    }else{

        tmp = (tmp << 32) | avio_rl32(s->pb);

        size2 = (tmp >> (44 - curbits)) & 0xFFFFF;

    }

    curbits += 20;

    avio_seek(s->pb, pos, SEEK_SET);

    size = ((size2 + curbits + 31) & ~31) >> 3;

    if(cur == c->frames_noted){

        c->frames[cur].pos = pos;

        c->frames[cur].size = size;

        c->frames[cur].skip = curbits - 20;

        av_add_index_entry(s->streams[0], cur, cur, size, 0, AVINDEX_KEYFRAME);

        c->frames_noted++;

    }

    c->curbits = (curbits + size2) & 0x1F;

    if (av_new_packet(pkt, size) < 0)

        return AVERROR(EIO);

    pkt->data[0] = curbits;

    pkt->data[1] = (c->curframe > c->fcount);

    pkt->data[2] = 0;

    pkt->data[3] = 0;

    pkt->stream_index = 0;

    pkt->pts = cur;

    ret = avio_read(s->pb, pkt->data + 4, size);

    if(c->curbits)

        avio_seek(s->pb, -4, SEEK_CUR);

    if(ret < size){

        av_free_packet(pkt);

        return AVERROR(EIO);

    }

    pkt->size = ret + 4;

    return 0;

}

static int mpc_read_close(AVFormatContext *s)

{

    MPCContext *c = s->priv_data;

    av_freep(&c->frames);

    return 0;

}

/**

 * Seek to the given position

 * If position is unknown but is within the limits of file

 * then packets are skipped unless desired position is reached

 *

 * Also this function makes use of the fact that timestamp == frameno

 */

static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)

{

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

    MPCContext *c = s->priv_data;

    AVPacket pkt1, *pkt = &pkt1;

    int ret;

    int index = av_index_search_timestamp(st, timestamp - DELAY_FRAMES, flags);

    uint32_t lastframe;

    /* if found, seek there */

    if (index >= 0){

        c->curframe = st->index_entries[index].pos;

        return 0;

    }

    /* if timestamp is out of bounds, return error */

    if(timestamp < 0 || timestamp >= c->fcount)

        return -1;

    timestamp -= DELAY_FRAMES;

    /* seek to the furthest known position and read packets until

       we reach desired position */

    lastframe = c->curframe;

    if(c->frames_noted) c->curframe = c->frames_noted - 1;

    while(c->curframe < timestamp){

        ret = av_read_frame(s, pkt);

        if (ret < 0){

            c->curframe = lastframe;

            return -1;

        }

        av_free_packet(pkt);

    }

    return 0;

}

AVInputFormat ff_mpc_demuxer = {

    "mpc",

    NULL_IF_CONFIG_SMALL("Musepack"),

    sizeof(MPCContext),

    mpc_probe,

    mpc_read_header,

    mpc_read_packet,

    mpc_read_close,

    mpc_read_seek,

    .extensions = "mpc",

};