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

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

    get_be32(pb); /* preview time */
    get_be32(pb); /* preview duration */
    get_be32(pb); /* poster time */
    get_be32(pb); /* selection time */
    get_be32(pb); /* selection duration */
    get_be32(pb); /* current time */
    get_be32(pb); /* next track ID */

    return 0;
}

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

    if((uint64_t)atom.size > (1<<30))
        return -1;

    // currently SVQ3 decoder expect full STSD header - so let's fake it
    // this should be fixed and just SMI header should be passed
    av_free(st->codec->extradata);
    st->codec->extradata_size = 0x5a + atom.size;
    st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

    if (st->codec->extradata) {
        memcpy(st->codec->extradata, "SVQ3", 4); // fake
        get_buffer(pb, st->codec->extradata + 0x5a, atom.size);
        dprintf(c->fc, "Reading SMI %"PRId64"  %s\n", atom.size, st->codec->extradata + 0x5a);
    } else
        url_fskip(pb, atom.size);

    return 0;
}

static int mov_read_enda(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    int little_endian = get_be16(pb);

    if (little_endian) {
        switch (st->codec->codec_id) {
        case CODEC_ID_PCM_S24BE:
            st->codec->codec_id = CODEC_ID_PCM_S24LE;
            break;
        case CODEC_ID_PCM_S32BE:
            st->codec->codec_id = CODEC_ID_PCM_S32LE;
            break;
        default:
            break;
        }
    }
    return 0;
}

/* FIXME modify qdm2/svq3/h264 decoders to take full atom as extradata */
static int mov_read_extradata(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    if((uint64_t)atom.size > (1<<30))
        return -1;
    av_free(st->codec->extradata);
    st->codec->extradata_size = atom.size + 8;
    st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
    if (st->codec->extradata) {
        AV_WL32(st->codec->extradata + 4, atom.type);
        get_buffer(pb, st->codec->extradata + 8, atom.size);
    } else
        url_fskip(pb, atom.size);
    return 0;
}

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

    if((uint64_t)atom.size > (1<<30))
        return -1;

    if (st->codec->codec_id == CODEC_ID_QDM2) {
        // pass all frma atom to codec, needed at least for QDM2
        av_free(st->codec->extradata);
        st->codec->extradata_size = atom.size;
        st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

        if (st->codec->extradata) {
            get_buffer(pb, st->codec->extradata, atom.size);
        } else
            url_fskip(pb, atom.size);
    } else if (atom.size > 8) { /* to read frma, esds atoms */
        mov_read_default(c, pb, atom);
    } else
        url_fskip(pb, atom.size);
    return 0;
}

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

    if((uint64_t)atom.size > (1<<30))
        return -1;

    av_free(st->codec->extradata);

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

    if (st->codec->extradata) {
        get_buffer(pb, st->codec->extradata, atom.size);
    } else
        url_fskip(pb, atom.size);

    return 0;
}

static int mov_read_stco(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(int64_t))
        return -1;

    sc->chunk_count = entries;
    sc->chunk_offsets = av_malloc(entries * sizeof(int64_t));
    if (!sc->chunk_offsets)
        return -1;
    if (atom.type == MKTAG('s', 't', 'c', 'o')) {
        for(i=0; i<entries; i++) {
            sc->chunk_offsets[i] = get_be32(pb);
        }
    } else if (atom.type == MKTAG('c', 'o', '6', '4')) {
        for(i=0; i<entries; i++) {
            sc->chunk_offsets[i] = get_be64(pb);
        }
    } else
        return -1;

    return 0;
}

static int mov_read_stsd(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
{
    AVStream *st = c->fc->streams[c->fc->nb_streams-1];
    MOVStreamContext *sc = st->priv_data;
    int entries, frames_per_sample;
    uint32_t format;
    uint8_t codec_name[32];

    /* for palette traversal */
    int color_depth;
    int color_start;
    int color_count;
    int color_end;
    int color_index;
    int color_dec;
    int color_greyscale;
    unsigned char *color_table;
    int j;
    unsigned char r, g, b;

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

    entries = get_be32(pb);

    while(entries--) { //Parsing Sample description table
        enum CodecID id;
        MOV_atom_t a = { 0, 0, 0 };
        offset_t start_pos = url_ftell(pb);
        int size = get_be32(pb); /* size */
        format = get_le32(pb); /* data format */

        get_be32(pb); /* reserved */
        get_be16(pb); /* reserved */
        get_be16(pb); /* index */

        if (st->codec->codec_tag) {
            /* multiple fourcc, just skip for now */
            url_fskip(pb, size - (url_ftell(pb) - start_pos));
            continue;
        }

        st->codec->codec_tag = format;
        id = codec_get_id(codec_movaudio_tags, format);
        if (id<=0 && (format&0xFFFF) == 'm' + ('s'<<8))
            id = codec_get_id(codec_wav_tags, bswap_32(format)&0xFFFF);

        if (st->codec->codec_type != CODEC_TYPE_VIDEO && id > 0) {
            st->codec->codec_type = CODEC_TYPE_AUDIO;
        } else if (st->codec->codec_type != CODEC_TYPE_AUDIO && /* do not overwrite codec type */
                   format && format != MKTAG('m', 'p', '4', 's')) { /* skip old asf mpeg4 tag */
            id = codec_get_id(codec_movvideo_tags, format);
            if (id <= 0)
                id = codec_get_id(codec_bmp_tags, format);
            if (id > 0)
                st->codec->codec_type = CODEC_TYPE_VIDEO;
        }

        dprintf(c->fc, "size=%d 4CC= %c%c%c%c codec_type=%d\n",
                size,
                (format >> 0) & 0xff, (format >> 8) & 0xff, (format >> 16) & 0xff, (format >> 24) & 0xff,
                st->codec->codec_type);

        if(st->codec->codec_type==CODEC_TYPE_VIDEO) {
            st->codec->codec_id = id;
            get_be16(pb); /* version */
            get_be16(pb); /* revision level */
            get_be32(pb); /* vendor */
            get_be32(pb); /* temporal quality */
            get_be32(pb); /* spacial quality */

            st->codec->width = get_be16(pb); /* width */
            st->codec->height = get_be16(pb); /* height */

            get_be32(pb); /* horiz resolution */
            get_be32(pb); /* vert resolution */
            get_be32(pb); /* data size, always 0 */
            frames_per_sample = get_be16(pb); /* frames per samples */

            dprintf(c->fc, "frames/samples = %d\n", frames_per_sample);

            get_buffer(pb, codec_name, 32); /* codec name, pascal string (FIXME: true for mp4?) */
            if (codec_name[0] <= 31) {
                memcpy(st->codec->codec_name, &codec_name[1],codec_name[0]);
                st->codec->codec_name[codec_name[0]] = 0;
            }

            st->codec->bits_per_sample = get_be16(pb); /* depth */
            st->codec->color_table_id = get_be16(pb); /* colortable id */

            /* figure out the palette situation */
            color_depth = st->codec->bits_per_sample & 0x1F;
            color_greyscale = st->codec->bits_per_sample & 0x20;

            /* if the depth is 2, 4, or 8 bpp, file is palettized */
            if ((color_depth == 2) || (color_depth == 4) ||
                (color_depth == 8)) {

                if (color_greyscale) {

                    /* compute the greyscale palette */
                    color_count = 1 << color_depth;
                    color_index = 255;
                    color_dec = 256 / (color_count - 1);
                    for (j = 0; j < color_count; j++) {
                        r = g = b = color_index;
                        c->palette_control.palette[j] =
                            (r << 16) | (g << 8) | (b);
                        color_index -= color_dec;
                        if (color_index < 0)
                            color_index = 0;
                    }

                } else if (st->codec->color_table_id & 0x08) {

                    /* if flag bit 3 is set, use the default palette */
                    color_count = 1 << color_depth;
                    if (color_depth == 2)
                        color_table = ff_qt_default_palette_4;
                    else if (color_depth == 4)
                        color_table = ff_qt_default_palette_16;
                    else
                        color_table = ff_qt_default_palette_256;

                    for (j = 0; j < color_count; j++) {
                        r = color_table[j * 4 + 0];
                        g = color_table[j * 4 + 1];
                        b = color_table[j * 4 + 2];
                        c->palette_control.palette[j] =
                            (r << 16) | (g << 8) | (b);
                    }

                } else {

                    /* load the palette from the file */
                    color_start = get_be32(pb);
                    color_count = get_be16(pb);
                    color_end = get_be16(pb);
                    for (j = color_start; j <= color_end; j++) {
                        /* each R, G, or B component is 16 bits;
                         * only use the top 8 bits; skip alpha bytes
                         * up front */
                        get_byte(pb);
                        get_byte(pb);
                        r = get_byte(pb);
                        get_byte(pb);
                        g = get_byte(pb);
                        get_byte(pb);
                        b = get_byte(pb);
                        get_byte(pb);
                        c->palette_control.palette[j] =
                            (r << 16) | (g << 8) | (b);
                    }
                }

                st->codec->palctrl = &c->palette_control;
                st->codec->palctrl->palette_changed = 1;
            } else
                st->codec->palctrl = NULL;
        } else if(st->codec->codec_type==CODEC_TYPE_AUDIO) {
            int bits_per_sample;
            uint16_t version = get_be16(pb);

            st->codec->codec_id = id;
            get_be16(pb); /* revision level */
            get_be32(pb); /* vendor */

            st->codec->channels = get_be16(pb);             /* channel count */
            dprintf(c->fc, "audio channels %d\n", st->codec->channels);
            st->codec->bits_per_sample = get_be16(pb);      /* sample size */
            /* do we need to force to 16 for AMR ? */

            /* handle specific s8 codec */
            get_be16(pb); /* compression id = 0*/
            get_be16(pb); /* packet size = 0 */

            st->codec->sample_rate = ((get_be32(pb) >> 16));

            switch (st->codec->codec_id) {
            case CODEC_ID_PCM_S8:
            case CODEC_ID_PCM_U8:
                if (st->codec->bits_per_sample == 16)
                    st->codec->codec_id = CODEC_ID_PCM_S16BE;
                break;
            case CODEC_ID_PCM_S16LE:
            case CODEC_ID_PCM_S16BE:
                if (st->codec->bits_per_sample == 8)
                    st->codec->codec_id = CODEC_ID_PCM_S8;
                else if (st->codec->bits_per_sample == 24)
                    st->codec->codec_id = CODEC_ID_PCM_S24BE;
                break;
            default:
                break;
            }

            //Read QT version 1 fields. In version 0 these do not exist.
            dprintf(c->fc, "version =%d, isom =%d\n",version,c->isom);
            if(!c->isom) {
                if(version==1) {
                    sc->samples_per_frame = get_be32(pb);
                    get_be32(pb); /* bytes per packet */
                    sc->bytes_per_frame = get_be32(pb);
                    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 */
                }
            }

            bits_per_sample = av_get_bits_per_sample(st->codec->codec_id);
            if (bits_per_sample) {
                st->codec->bits_per_sample = bits_per_sample;
                sc->sample_size = (bits_per_sample >> 3) * st->codec->channels;
            }
        } 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;
    }

    /* special codec parameters handling */
    switch (st->codec->codec_id) {
#ifdef CONFIG_H261_DECODER
    case CODEC_ID_H261:
#endif
#ifdef CONFIG_H263_DECODER
    case CODEC_ID_H263:
#endif
#ifdef CONFIG_MPEG4_DECODER
    case CODEC_ID_MPEG4:
#endif
        st->codec->width= 0; /* let decoder init width/height */
        st->codec->height= 0;
        break;
#ifdef CONFIG_LIBFAAD
    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;
#ifdef CONFIG_DV_DEMUXER
    case CODEC_ID_DVAUDIO: