mov.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

        c->dv_fctx = av_alloc_format_context();
        c->dv_demux = dv_init_demux(c->dv_fctx);
        if (!c->dv_demux) {
            av_log(c->fc, AV_LOG_ERROR, "dv demux context init error\n");
            return -1;
        }
        sc->dv_audio_container = 1;
        st->codec->codec_id = CODEC_ID_PCM_S16LE;
        break;
#endif
    /* no ifdef since parameters are always those */
    case CODEC_ID_AMR_WB:
        st->codec->sample_rate= 16000;
        st->codec->channels= 1; /* really needed */
        break;
    case CODEC_ID_AMR_NB:
        st->codec->sample_rate= 8000;
        st->codec->channels= 1; /* really needed */
        break;
    case CODEC_ID_MP2:
    case CODEC_ID_MP3:
        st->codec->codec_type = CODEC_TYPE_AUDIO; /* force type after stsd for m1a hdlr */
        st->need_parsing = AVSTREAM_PARSE_FULL;
        break;
    case CODEC_ID_ADPCM_MS:
    case CODEC_ID_ADPCM_IMA_WAV:
        st->codec->block_align = sc->bytes_per_frame;
        break;
    default:
        break;
    }

    return 0;
}

static int mov_read_stsc(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    MOVStreamContext *sc = st->priv_data;
    unsigned int i, entries;

    get_byte(pb); /* version */
    get_byte(pb); get_byte(pb); get_byte(pb); /* flags */

    entries = get_be32(pb);

    if(entries >= UINT_MAX / sizeof(MOV_stsc_t))
        return -1;

    dprintf(c->fc, "track[%i].stsc.entries = %i\n", c->fc->nb_streams-1, entries);

    sc->sample_to_chunk_sz = entries;
    sc->sample_to_chunk = av_malloc(entries * sizeof(MOV_stsc_t));
    if (!sc->sample_to_chunk)
        return -1;
    for(i=0; i<entries; i++) {
        sc->sample_to_chunk[i].first = get_be32(pb);
        sc->sample_to_chunk[i].count = get_be32(pb);
        sc->sample_to_chunk[i].id = get_be32(pb);
    }
    return 0;
}

static int mov_read_stss(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    MOVStreamContext *sc = st->priv_data;
    unsigned int i, entries;

    get_byte(pb); /* version */
    get_byte(pb); get_byte(pb); get_byte(pb); /* flags */

    entries = get_be32(pb);

    if(entries >= UINT_MAX / sizeof(int))
        return -1;

    sc->keyframe_count = entries;

    dprintf(c->fc, "keyframe_count = %d\n", sc->keyframe_count);

    sc->keyframes = av_malloc(entries * sizeof(int));
    if (!sc->keyframes)
        return -1;
    for(i=0; i<entries; i++) {
        sc->keyframes[i] = get_be32(pb);
        //dprintf(c->fc, "keyframes[]=%d\n", sc->keyframes[i]);
    }
    return 0;
}

static int mov_read_stsz(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    MOVStreamContext *sc = st->priv_data;
    unsigned int i, entries, sample_size;

    get_byte(pb); /* version */
    get_byte(pb); get_byte(pb); get_byte(pb); /* flags */

    sample_size = get_be32(pb);
    if (!sc->sample_size) /* do not overwrite value computed in stsd */
        sc->sample_size = sample_size;
    entries = get_be32(pb);
    if(entries >= UINT_MAX / sizeof(int))
        return -1;

    sc->sample_count = entries;
    if (sample_size)
        return 0;

    dprintf(c->fc, "sample_size = %d sample_count = %d\n", sc->sample_size, sc->sample_count);

    sc->sample_sizes = av_malloc(entries * sizeof(int));
    if (!sc->sample_sizes)
        return -1;
    for(i=0; i<entries; i++) {
        sc->sample_sizes[i] = get_be32(pb);
        dprintf(c->fc, "sample_sizes[]=%d\n", sc->sample_sizes[i]);
    }
    return 0;
}

static int mov_read_stts(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    MOVStreamContext *sc = st->priv_data;
    unsigned int i, entries;
    int64_t duration=0;
    int64_t total_sample_count=0;

    get_byte(pb); /* version */
    get_byte(pb); get_byte(pb); get_byte(pb); /* flags */
    entries = get_be32(pb);
    if(entries >= UINT_MAX / sizeof(MOV_stts_t))
        return -1;

    sc->stts_count = entries;
    sc->stts_data = av_malloc(entries * sizeof(MOV_stts_t));

    dprintf(c->fc, "track[%i].stts.entries = %i\n", c->fc->nb_streams-1, entries);

    sc->time_rate=0;

    for(i=0; i<entries; i++) {
        int sample_duration;
        int sample_count;

        sample_count=get_be32(pb);
        sample_duration = get_be32(pb);
        sc->stts_data[i].count= sample_count;
        sc->stts_data[i].duration= sample_duration;

        sc->time_rate= ff_gcd(sc->time_rate, sample_duration);

        dprintf(c->fc, "sample_count=%d, sample_duration=%d\n",sample_count,sample_duration);

        duration+=(int64_t)sample_duration*sample_count;
        total_sample_count+=sample_count;
    }

    st->nb_frames= total_sample_count;
    if(duration)
        st->duration= duration;
    return 0;
}

static int mov_read_ctts(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    MOVStreamContext *sc = st->priv_data;
    unsigned int i, entries;

    get_byte(pb); /* version */
    get_byte(pb); get_byte(pb); get_byte(pb); /* flags */
    entries = get_be32(pb);
    if(entries >= UINT_MAX / sizeof(MOV_stts_t))
        return -1;

    sc->ctts_count = entries;
    sc->ctts_data = av_malloc(entries * sizeof(MOV_stts_t));

    dprintf(c->fc, "track[%i].ctts.entries = %i\n", c->fc->nb_streams-1, entries);

    for(i=0; i<entries; i++) {
        int count    =get_be32(pb);
        int duration =get_be32(pb);

        if (duration < 0) {
            av_log(c->fc, AV_LOG_ERROR, "negative ctts, ignoring\n");
            sc->ctts_count = 0;
            url_fskip(pb, 8 * (entries - i - 1));
            break;
        }
        sc->ctts_data[i].count   = count;
        sc->ctts_data[i].duration= duration;

        sc->time_rate= ff_gcd(sc->time_rate, duration);
    }
    return 0;
}

static int mov_read_trak(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st;
    MOVStreamContext *sc;

    st = av_new_stream(c->fc, c->fc->nb_streams);
    if (!st) return -2;
    sc = av_mallocz(sizeof(MOVStreamContext));
    if (!sc) {
        av_free(st);
        return -1;
    }

    st->priv_data = sc;
    st->codec->codec_type = CODEC_TYPE_DATA;
    st->start_time = 0; /* XXX: check */
    c->streams[c->fc->nb_streams-1] = sc;

    return mov_read_default(c, pb, atom);
}

static void mov_parse_udta_string(ByteIOContext *pb, char *str, int size)
{
    uint16_t str_size = get_be16(pb); /* string length */;

    get_be16(pb); /* skip language */
    get_buffer(pb, str, FFMIN(size, str_size));
}

static int mov_read_udta(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    uint64_t end = url_ftell(pb) + atom.size;

    while (url_ftell(pb) + 8 < end) {
        uint32_t tag_size = get_be32(pb);
        uint32_t tag      = get_le32(pb);
        uint64_t next     = url_ftell(pb) + tag_size - 8;

        if (next > end) // stop if tag_size is wrong
            break;

        switch (tag) {
        case MKTAG(0xa9,'n','a','m'):
            mov_parse_udta_string(pb, c->fc->title,     sizeof(c->fc->title));
            break;
        case MKTAG(0xa9,'w','r','t'):
            mov_parse_udta_string(pb, c->fc->author,    sizeof(c->fc->author));
            break;
        case MKTAG(0xa9,'c','p','y'):
            mov_parse_udta_string(pb, c->fc->copyright, sizeof(c->fc->copyright));
            break;
        case MKTAG(0xa9,'i','n','f'):
            mov_parse_udta_string(pb, c->fc->comment,   sizeof(c->fc->comment));
            break;
        default:
            break;
        }

        url_fseek(pb, next, SEEK_SET);
    }

    return 0;
}

static int mov_read_tkhd(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    int version = get_byte(pb);

    get_byte(pb); get_byte(pb);
    get_byte(pb); /* flags */
    /*
    MOV_TRACK_ENABLED 0x0001
    MOV_TRACK_IN_MOVIE 0x0002
    MOV_TRACK_IN_PREVIEW 0x0004
    MOV_TRACK_IN_POSTER 0x0008
    */

    if (version == 1) {
        get_be64(pb);
        get_be64(pb);
    } else {
        get_be32(pb); /* creation time */
        get_be32(pb); /* modification time */
    }
    st->id = (int)get_be32(pb); /* track id (NOT 0 !)*/
    get_be32(pb); /* reserved */
    st->start_time = 0; /* check */
    (version == 1) ? get_be64(pb) : get_be32(pb); /* highlevel (considering edits) duration in movie timebase */
    get_be32(pb); /* reserved */
    get_be32(pb); /* reserved */

    get_be16(pb); /* layer */
    get_be16(pb); /* alternate group */
    get_be16(pb); /* volume */
    get_be16(pb); /* reserved */

    url_fskip(pb, 36); /* display matrix */

    /* those are fixed-point */
    get_be32(pb); /* track width */
    get_be32(pb); /* track height */

    return 0;
}

/* this atom should be null (from specs), but some buggy files put the 'moov' atom inside it... */
/* like the files created with Adobe Premiere 5.0, for samples see */
/* http://graphics.tudelft.nl/~wouter/publications/soundtests/ */
static int mov_read_wide(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    int err;

    if (atom.size < 8)
        return 0; /* continue */
    if (get_be32(pb) != 0) { /* 0 sized mdat atom... use the 'wide' atom size */
        url_fskip(pb, atom.size - 4);
        return 0;
    }
    atom.type = get_le32(pb);
    atom.offset += 8;
    atom.size -= 8;
    if (atom.type != MKTAG('m', 'd', 'a', 't')) {
        url_fskip(pb, atom.size);
        return 0;
    }
    err = mov_read_mdat(c, pb, atom);
    return err;
}

static int mov_read_cmov(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
#ifdef CONFIG_ZLIB
    ByteIOContext ctx;
    uint8_t *cmov_data;
    uint8_t *moov_data; /* uncompressed data */
    long cmov_len, moov_len;
    int ret;

    get_be32(pb); /* dcom atom */
    if (get_le32(pb) != MKTAG( 'd', 'c', 'o', 'm' ))
        return -1;
    if (get_le32(pb) != MKTAG( 'z', 'l', 'i', 'b' )) {
        av_log(NULL, AV_LOG_ERROR, "unknown compression for cmov atom !");
        return -1;
    }
    get_be32(pb); /* cmvd atom */
    if (get_le32(pb) != MKTAG( 'c', 'm', 'v', 'd' ))
        return -1;
    moov_len = get_be32(pb); /* uncompressed size */
    cmov_len = atom.size - 6 * 4;

    cmov_data = av_malloc(cmov_len);
    if (!cmov_data)
        return -1;
    moov_data = av_malloc(moov_len);
    if (!moov_data) {
        av_free(cmov_data);
        return -1;
    }
    get_buffer(pb, cmov_data, cmov_len);
    if(uncompress (moov_data, (uLongf *) &moov_len, (const Bytef *)cmov_data, cmov_len) != Z_OK)
        return -1;
    if(init_put_byte(&ctx, moov_data, moov_len, 0, NULL, NULL, NULL, NULL) != 0)
        return -1;
    atom.type = MKTAG( 'm', 'o', 'o', 'v' );
    atom.offset = 0;
    atom.size = moov_len;
#ifdef DEBUG
//    { int fd = open("/tmp/uncompheader.mov", O_WRONLY | O_CREAT); write(fd, moov_data, moov_len); close(fd); }
#endif
    ret = mov_read_default(c, &ctx, atom);
    av_free(moov_data);
    av_free(cmov_data);
    return ret;
#else
    av_log(c->fc, AV_LOG_ERROR, "this file requires zlib support compiled in\n");
    return -1;
#endif
}

/* edit list atom */
static int mov_read_elst(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    int i, edit_count;

    get_byte(pb); /* version */
    get_byte(pb); get_byte(pb); get_byte(pb); /* flags */
    edit_count= c->streams[c->fc->nb_streams-1]->edit_count = get_be32(pb);     /* entries */

    for(i=0; i<edit_count; i++){
        get_be32(pb); /* Track duration */
        get_be32(pb); /* Media time */
        get_be32(pb); /* Media rate */
    }
    dprintf(c->fc, "track[%i].edit_count = %i\n", c->fc->nb_streams-1, c->streams[c->fc->nb_streams-1]->edit_count);
    return 0;
}

static const MOVParseTableEntry mov_default_parse_table[] = {
/* mp4 atoms */
{ MKTAG( 'c', 'o', '6', '4' ), mov_read_stco },
{ MKTAG( 'c', 't', 't', 's' ), mov_read_ctts }, /* composition time to sample */
{ MKTAG( 'e', 'd', 't', 's' ), mov_read_default },
{ MKTAG( 'e', 'l', 's', 't' ), mov_read_elst },
{ MKTAG( 'e', 'n', 'd', 'a' ), mov_read_enda },
{ MKTAG( 'f', 'i', 'e', 'l' ), mov_read_extradata },
{ MKTAG( 'f', 't', 'y', 'p' ), mov_read_ftyp },
{ MKTAG( 'h', 'd', 'l', 'r' ), mov_read_hdlr },