mov.c

ffmpeg源码分析

                get_be32(pb); /* bytes per frame */
                get_be32(pb); /* bytes per sample */
            } else if(version==2) {
                get_be32(pb); /* sizeof struct only */
                st->codec->sample_rate = av_int2dbl(get_be64(pb)); /* float 64 */
                st->codec->channels = get_be32(pb);
                get_be32(pb); /* always 0x7F000000 */
                get_be32(pb); /* bits per channel if sound is uncompressed */
                get_be32(pb); /* lcpm format specific flag */
                get_be32(pb); /* bytes per audio packet if constant */
                get_be32(pb); /* lpcm frames per audio packet if constant */
            }
        } else {
            /* other codec type, just skip (rtp, mp4s, tmcd ...) */
            url_fskip(pb, size - (url_ftell(pb) - start_pos));
        }
        /* this will read extra atoms at the end (wave, alac, damr, avcC, SMI ...) */
        a.size = size - (url_ftell(pb) - start_pos);
        if (a.size > 8)
            mov_read_default(c, pb, a);
        else if (a.size > 0)
            url_fskip(pb, a.size);
    }

    if(st->codec->codec_type==CODEC_TYPE_AUDIO && st->codec->sample_rate==0 && sc->time_scale>1) {
        st->codec->sample_rate= sc->time_scale;
    }

    switch (st->codec->codec_id) {
#ifdef CONFIG_FAAD
    case CODEC_ID_AAC:
#endif
#ifdef CONFIG_VORBIS_DECODER
    case CODEC_ID_VORBIS:
#endif
    case CODEC_ID_MP3ON4:
        st->codec->sample_rate= 0; /* let decoder init parameters properly */
        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 = (MOVStreamContext *)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_sample_to_chunk_tbl))
        return -1;

#ifdef DEBUG
av_log(NULL, AV_LOG_DEBUG, "track[%i].stsc.entries = %i\n", c->fc->nb_streams-1, entries);
#endif
    sc->sample_to_chunk_sz = entries;
    sc->sample_to_chunk = (MOV_sample_to_chunk_tbl*) av_malloc(entries * sizeof(MOV_sample_to_chunk_tbl));
    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 = (MOVStreamContext *)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(long))
        return -1;

    sc->keyframe_count = entries;
#ifdef DEBUG
    av_log(NULL, AV_LOG_DEBUG, "keyframe_count = %ld\n", sc->keyframe_count);
#endif
    sc->keyframes = (long*) av_malloc(entries * sizeof(long));
    if (!sc->keyframes)
        return -1;
    for(i=0; i<entries; i++) {
        sc->keyframes[i] = get_be32(pb);
#ifdef DEBUG
/*        av_log(NULL, AV_LOG_DEBUG, "keyframes[]=%ld\n", sc->keyframes[i]); */
#endif
    }
    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 = (MOVStreamContext *)st->priv_data;
    unsigned int i, entries;

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

    sc->sample_size = get_be32(pb);
    entries = get_be32(pb);
    if(entries >= UINT_MAX / sizeof(long))
        return -1;

    sc->sample_count = entries;
#ifdef DEBUG
    av_log(NULL, AV_LOG_DEBUG, "sample_size = %ld sample_count = %ld\n", sc->sample_size, sc->sample_count);
#endif
    if(sc->sample_size) {
        /* override sample size for uncompressed sound */
        switch (st->codec->codec_id) {
        case CODEC_ID_PCM_S32BE:
        case CODEC_ID_PCM_S32LE:
            sc->sample_size = 4 * st->codec->channels;
            break;
        case CODEC_ID_PCM_S24BE:
        case CODEC_ID_PCM_S24LE:
            sc->sample_size = 3 * st->codec->channels;
            break;
        case CODEC_ID_PCM_S16BE:
        case CODEC_ID_PCM_S16LE:
            sc->sample_size = 2 * st->codec->channels;
            break;
        case CODEC_ID_PCM_MULAW:
        case CODEC_ID_PCM_ALAW:
        case CODEC_ID_PCM_S8:
        case CODEC_ID_PCM_U8:
            sc->sample_size = 1 * st->codec->channels;
            break;
        default:
            break;
        }
        assert(sc->sample_size);
        return 0; /* there isn't any table following */
    }
    sc->sample_sizes = (long*) av_malloc(entries * sizeof(long));
    if (!sc->sample_sizes)
        return -1;
    for(i=0; i<entries; i++) {
        sc->sample_sizes[i] = get_be32(pb);
#ifdef DEBUG
        av_log(NULL, AV_LOG_DEBUG, "sample_sizes[]=%ld\n", sc->sample_sizes[i]);
#endif
    }
    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 = (MOVStreamContext *)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(Time2Sample))
        return -1;

    sc->stts_count = entries;
    sc->stts_data = av_malloc(entries * sizeof(Time2Sample));

#ifdef DEBUG
av_log(NULL, AV_LOG_DEBUG, "track[%i].stts.entries = %i\n", c->fc->nb_streams-1, entries);
#endif

    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("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 = (MOVStreamContext *)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(Time2Sample))
        return -1;

    sc->ctts_count = entries;
    sc->ctts_data = av_malloc(entries * sizeof(Time2Sample));

    dprintf("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 = (MOVStreamContext*) av_mallocz(sizeof(MOVStreamContext));
    if (!sc) {
        av_free(st);
        return -1;
    }

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

    return mov_read_default(c, pb, atom);
}

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 */
    /*st->codec->width =*/ get_be32(pb) >> 16; /* track width */
    /*st->codec->height =*/ get_be32(pb) >> 16; /* 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;
}


#ifdef CONFIG_ZLIB
static int null_read_packet(void *opaque, uint8_t *buf, int buf_size)
{
    return -1;
}

static int mov_read_cmov(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    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 = (uint8_t *) av_malloc(cmov_len);
    if (!cmov_data)
        return -1;
    moov_data = (uint8_t *) 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_read_packet, NULL, NULL) != 0)
        return -1;