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ffmpeg / libavformat / mpc8.c @ e356fc57

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/*
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 * Musepack SV8 demuxer
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 * Copyright (c) 2007 Konstantin Shishkov
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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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#include "libavcodec/get_bits.h"
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#include "libavcodec/unary.h"
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#include "avformat.h"
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/// Two-byte MPC tag
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#define MKMPCTAG(a, b) (a | (b << 8))
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#define TAG_MPCK MKTAG('M','P','C','K')
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/// Reserved MPC tags
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enum MPCPacketTags{
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    TAG_STREAMHDR   = MKMPCTAG('S','H'),
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    TAG_STREAMEND   = MKMPCTAG('S','E'),
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    TAG_AUDIOPACKET = MKMPCTAG('A','P'),
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    TAG_SEEKTBLOFF  = MKMPCTAG('S','O'),
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    TAG_SEEKTABLE   = MKMPCTAG('S','T'),
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    TAG_REPLAYGAIN  = MKMPCTAG('R','G'),
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    TAG_ENCINFO     = MKMPCTAG('E','I'),
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};
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static const int mpc8_rate[8] = { 44100, 48000, 37800, 32000, -1, -1, -1, -1 };
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typedef struct {
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    int ver;
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    int frame;
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    int64_t header_pos;
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    int64_t samples;
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} MPCContext;
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static inline int64_t bs_get_v(uint8_t **bs)
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{
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    int64_t v = 0;
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    int br = 0;
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    int c;
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    do {
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        c = **bs; (*bs)++;
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        v <<= 7;
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        v |= c & 0x7F;
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        br++;
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        if (br > 10)
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            return -1;
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    } while (c & 0x80);
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    return v - br;
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}
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static int mpc8_probe(AVProbeData *p)
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{
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    uint8_t *bs = p->buf + 4;
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    uint8_t *bs_end = bs + p->buf_size;
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    int64_t size;
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    if (p->buf_size < 16)
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        return 0;
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    if (AV_RL32(p->buf) != TAG_MPCK)
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        return 0;
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    while (bs < bs_end + 3) {
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        int header_found = (bs[0] == 'S' && bs[1] == 'H');
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        if (bs[0] < 'A' || bs[0] > 'Z' || bs[1] < 'A' || bs[1] > 'Z')
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            return 0;
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        bs += 2;
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        size = bs_get_v(&bs);
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        if (size < 2)
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            return 0;
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        if (bs + size - 2 >= bs_end)
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            return AVPROBE_SCORE_MAX / 4 - 1; //seems to be valid MPC but no header yet
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        if (header_found) {
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            if (size < 11 || size > 28)
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                return 0;
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            if (!AV_RL32(bs)) //zero CRC is invalid
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                return 0;
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            return AVPROBE_SCORE_MAX;
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        } else {
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            bs += size - 2;
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        }
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    }
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    return 0;
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}
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static inline int64_t gb_get_v(GetBitContext *gb)
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{
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    int64_t v = 0;
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    int bits = 0;
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    while(get_bits1(gb) && bits < 64-7){
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        v <<= 7;
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        v |= get_bits(gb, 7);
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        bits += 7;
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    }
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    v <<= 7;
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    v |= get_bits(gb, 7);
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    return v;
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}
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static void mpc8_get_chunk_header(AVIOContext *pb, int *tag, int64_t *size)
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{
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    int64_t pos;
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    pos = url_ftell(pb);
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    *tag = avio_rl16(pb);
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    *size = ff_get_v(pb);
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    *size -= url_ftell(pb) - pos;
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}
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static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
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{
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    MPCContext *c = s->priv_data;
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    int tag;
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    int64_t size, pos, ppos[2];
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    uint8_t *buf;
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    int i, t, seekd;
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    GetBitContext gb;
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    avio_seek(s->pb, off, SEEK_SET);
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    mpc8_get_chunk_header(s->pb, &tag, &size);
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    if(tag != TAG_SEEKTABLE){
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        av_log(s, AV_LOG_ERROR, "No seek table at given position\n");
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        return;
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    }
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    if(!(buf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE)))
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        return;
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    avio_read(s->pb, buf, size);
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    init_get_bits(&gb, buf, size * 8);
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    size = gb_get_v(&gb);
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    if(size > UINT_MAX/4 || size > c->samples/1152){
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        av_log(s, AV_LOG_ERROR, "Seek table is too big\n");
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        return;
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    }
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    seekd = get_bits(&gb, 4);
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    for(i = 0; i < 2; i++){
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        pos = gb_get_v(&gb) + c->header_pos;
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        ppos[1 - i] = pos;
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        av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
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    }
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    for(; i < size; i++){
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        t = get_unary(&gb, 1, 33) << 12;
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        t += get_bits(&gb, 12);
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        if(t & 1)
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            t = -(t & ~1);
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        pos = (t >> 1) + ppos[0]*2 - ppos[1];
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        av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);
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        ppos[1] = ppos[0];
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        ppos[0] = pos;
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    }
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    av_free(buf);
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}
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static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size)
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{
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    AVIOContext *pb = s->pb;
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    int64_t pos, off;
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    switch(tag){
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    case TAG_SEEKTBLOFF:
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        pos = url_ftell(pb) + size;
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        off = ff_get_v(pb);
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        mpc8_parse_seektable(s, chunk_pos + off);
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        avio_seek(pb, pos, SEEK_SET);
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        break;
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    default:
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        avio_seek(pb, size, SEEK_CUR);
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    }
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}
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static int mpc8_read_header(AVFormatContext *s, AVFormatParameters *ap)
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{
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    MPCContext *c = s->priv_data;
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    AVIOContext *pb = s->pb;
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    AVStream *st;
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    int tag = 0;
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    int64_t size, pos;
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    c->header_pos = url_ftell(pb);
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    if(avio_rl32(pb) != TAG_MPCK){
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        av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n");
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        return -1;
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    }
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    while(!url_feof(pb)){
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        pos = url_ftell(pb);
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        mpc8_get_chunk_header(pb, &tag, &size);
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        if(tag == TAG_STREAMHDR)
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            break;
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        mpc8_handle_chunk(s, tag, pos, size);
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    }
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    if(tag != TAG_STREAMHDR){
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        av_log(s, AV_LOG_ERROR, "Stream header not found\n");
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        return -1;
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    }
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    pos = url_ftell(pb);
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    avio_seek(pb, 4, SEEK_CUR); //CRC
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    c->ver = avio_r8(pb);
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    if(c->ver != 8){
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        av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver);
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        return -1;
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    }
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    c->samples = ff_get_v(pb);
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    ff_get_v(pb); //silence samples at the beginning
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    st = av_new_stream(s, 0);
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    if (!st)
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        return AVERROR(ENOMEM);
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    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
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    st->codec->codec_id = CODEC_ID_MUSEPACK8;
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    st->codec->bits_per_coded_sample = 16;
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    st->codec->extradata_size = 2;
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    st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
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    avio_read(pb, st->codec->extradata, st->codec->extradata_size);
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    st->codec->channels = (st->codec->extradata[1] >> 4) + 1;
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    st->codec->sample_rate = mpc8_rate[st->codec->extradata[0] >> 5];
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    av_set_pts_info(st, 32, 1152  << (st->codec->extradata[1]&3)*2, st->codec->sample_rate);
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    st->duration = c->samples / (1152 << (st->codec->extradata[1]&3)*2);
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    size -= url_ftell(pb) - pos;
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    return 0;
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}
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static int mpc8_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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    MPCContext *c = s->priv_data;
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    int tag;
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    int64_t pos, size;
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    while(!url_feof(s->pb)){
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        pos = url_ftell(s->pb);
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        mpc8_get_chunk_header(s->pb, &tag, &size);
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        if (size < 0)
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            return -1;
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        if(tag == TAG_AUDIOPACKET){
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            if(av_get_packet(s->pb, pkt, size) < 0)
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                return AVERROR(ENOMEM);
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            pkt->stream_index = 0;
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            pkt->pts = c->frame;
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            return 0;
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        }
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        if(tag == TAG_STREAMEND)
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            return AVERROR(EIO);
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        mpc8_handle_chunk(s, tag, pos, size);
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    }
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    return 0;
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}
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static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
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{
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    AVStream *st = s->streams[stream_index];
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    MPCContext *c = s->priv_data;
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    int index = av_index_search_timestamp(st, timestamp, flags);
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    if(index < 0) return -1;
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    avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET);
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    c->frame = st->index_entries[index].timestamp;
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    return 0;
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}
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AVInputFormat ff_mpc8_demuxer = {
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    "mpc8",
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    NULL_IF_CONFIG_SMALL("Musepack SV8"),
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    sizeof(MPCContext),
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    mpc8_probe,
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    mpc8_read_header,
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    mpc8_read_packet,
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    NULL,
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    mpc8_read_seek,
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};