mxf.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

/*
 * MXF demuxer.
 * Copyright (c) 2006 SmartJog S.A., Baptiste Coudurier <baptiste dot coudurier at smartjog dot com>.
 *
 * 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
 */

/*
 * References
 * SMPTE 336M KLV Data Encoding Protocol Using Key-Length-Value
 * SMPTE 377M MXF File Format Specifications
 * SMPTE 378M Operational Pattern 1a
 * SMPTE 379M MXF Generic Container
 * SMPTE 381M Mapping MPEG Streams into the MXF Generic Container
 * SMPTE 382M Mapping AES3 and Broadcast Wave Audio into the MXF Generic Container
 * SMPTE 383M Mapping DV-DIF Data to the MXF Generic Container
 *
 * Principle
 * Search for Track numbers which will identify essence element KLV packets.
 * Search for SourcePackage which define tracks which contains Track numbers.
 * Material Package contains tracks with reference to SourcePackage tracks.
 * Search for Descriptors (Picture, Sound) which contains codec info and parameters.
 * Assign Descriptors to correct Tracks.
 *
 * Metadata reading functions read Local Tags, get InstanceUID(0x3C0A) then add MetaDataSet to MXFContext.
 * Metadata parsing resolves Strong References to objects.
 *
 * Simple demuxer, only OP1A supported and some files might not work at all.
 * Only tracks with associated descriptors will be decoded. "Highly Desirable" SMPTE 377M D.1
 */

//#define DEBUG

#include "avformat.h"
#include "aes.h"
#include "bytestream.h"

typedef uint8_t UID[16];

enum MXFMetadataSetType {
    AnyType,
    MaterialPackage,
    SourcePackage,
    SourceClip,
    TimecodeComponent,
    Sequence,
    MultipleDescriptor,
    Descriptor,
    Track,
    CryptoContext,
};

typedef struct {
    UID uid;
    enum MXFMetadataSetType type;
    UID context_uid;
    UID source_container_ul;
} MXFCryptoContext;

typedef struct {
    UID uid;
    enum MXFMetadataSetType type;
    UID source_package_uid;
    UID data_definition_ul;
    int64_t duration;
    int64_t start_position;
    int source_track_id;
} MXFStructuralComponent;

typedef struct {
    UID uid;
    enum MXFMetadataSetType type;
    UID data_definition_ul;
    UID *structural_components_refs;
    int structural_components_count;
    int64_t duration;
} MXFSequence;

typedef struct {
    UID uid;
    enum MXFMetadataSetType type;
    MXFSequence *sequence; /* mandatory, and only one */
    UID sequence_ref;
    int track_id;
    uint8_t track_number[4];
    AVRational edit_rate;
} MXFTrack;

typedef struct {
    UID uid;
    enum MXFMetadataSetType type;
    UID essence_container_ul;
    UID essence_codec_ul;
    AVRational sample_rate;
    AVRational aspect_ratio;
    int width;
    int height;
    int channels;
    int bits_per_sample;
    UID *sub_descriptors_refs;
    int sub_descriptors_count;
    int linked_track_id;
    uint8_t *extradata;
    int extradata_size;
} MXFDescriptor;

typedef struct {
    UID uid;
    enum MXFMetadataSetType type;
    UID package_uid;
    UID *tracks_refs;
    int tracks_count;
    MXFDescriptor *descriptor; /* only one */
    UID descriptor_ref;
} MXFPackage;

typedef struct {
    UID uid;
    enum MXFMetadataSetType type;
} MXFMetadataSet;

typedef struct {
    UID *packages_refs;
    int packages_count;
    MXFMetadataSet **metadata_sets;
    int metadata_sets_count;
    AVFormatContext *fc;
    struct AVAES *aesc;
} MXFContext;

typedef struct {
    UID key;
    offset_t offset;
    uint64_t length;
} KLVPacket;

enum MXFWrappingScheme {
    Frame,
    Clip,
};

typedef struct {
    UID uid;
    enum CodecID id;
    enum MXFWrappingScheme wrapping;
} MXFCodecUL;

typedef struct {
    UID uid;
    enum CodecType type;
} MXFDataDefinitionUL;

typedef struct {
    const UID key;
    int (*read)();
    int ctx_size;
    enum MXFMetadataSetType type;
} MXFMetadataReadTableEntry;

/* partial keys to match */
static const uint8_t mxf_header_partition_pack_key[]       = { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x02 };
static const uint8_t mxf_essence_element_key[]             = { 0x06,0x0e,0x2b,0x34,0x01,0x02,0x01,0x01,0x0d,0x01,0x03,0x01 };
static const uint8_t mxf_klv_key[]                         = { 0x06,0x0e,0x2b,0x34 };
/* complete keys to match */
static const uint8_t mxf_encrypted_triplet_key[]           = { 0x06,0x0e,0x2b,0x34,0x02,0x04,0x01,0x07,0x0d,0x01,0x03,0x01,0x02,0x7e,0x01,0x00 };
static const uint8_t mxf_encrypted_essence_container[]     = { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x07,0x0d,0x01,0x03,0x01,0x02,0x0b,0x01,0x00 };

#define IS_KLV_KEY(x, y) (!memcmp(x, y, sizeof(y)))

#define PRINT_KEY(pc, s, x) dprintf(pc, "%s %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X\n", s, \
                             (x)[0], (x)[1], (x)[2], (x)[3], (x)[4], (x)[5], (x)[6], (x)[7], (x)[8], (x)[9], (x)[10], (x)[11], (x)[12], (x)[13], (x)[14], (x)[15])

static int64_t klv_decode_ber_length(ByteIOContext *pb)
{
    uint64_t size = get_byte(pb);
    if (size & 0x80) { /* long form */
        int bytes_num = size & 0x7f;
        /* SMPTE 379M 5.3.4 guarantee that bytes_num must not exceed 8 bytes */
        if (bytes_num > 8)
            return -1;
        size = 0;
        while (bytes_num--)
            size = size << 8 | get_byte(pb);
    }
    return size;
}

static int mxf_read_sync(ByteIOContext *pb, const uint8_t *key, unsigned size)
{
    int i, b;
    for (i = 0; i < size && !url_feof(pb); i++) {
        b = get_byte(pb);
        if (b == key[0])
            i = 0;
        else if (b != key[i])
            i = -1;
    }
    return i == size;
}

static int klv_read_packet(KLVPacket *klv, ByteIOContext *pb)
{
    if (!mxf_read_sync(pb, mxf_klv_key, 4))
        return -1;
    klv->offset = url_ftell(pb) - 4;
    memcpy(klv->key, mxf_klv_key, 4);
    get_buffer(pb, klv->key + 4, 12);
    klv->length = klv_decode_ber_length(pb);
    return klv->length == -1 ? -1 : 0;
}

static int mxf_get_stream_index(AVFormatContext *s, KLVPacket *klv)
{
    int i;

    for (i = 0; i < s->nb_streams; i++) {
        MXFTrack *track = s->streams[i]->priv_data;
        /* SMPTE 379M 7.3 */
        if (!memcmp(klv->key + sizeof(mxf_essence_element_key), track->track_number, sizeof(track->track_number)))
            return i;
    }
    /* return 0 if only one stream, for OP Atom files with 0 as track number */
    return s->nb_streams == 1 ? 0 : -1;
}

/* XXX: use AVBitStreamFilter */
static int mxf_get_d10_aes3_packet(ByteIOContext *pb, AVStream *st, AVPacket *pkt, int64_t length)
{
    uint8_t buffer[61444];
    uint8_t *buf_ptr, *end_ptr, *data_ptr;
    int i;

    if (length > 61444) /* worst case PAL 1920 samples 8 channels */
        return -1;
    get_buffer(pb, buffer, length);
    av_new_packet(pkt, length);
    data_ptr = pkt->data;
    end_ptr = buffer + length;
    buf_ptr = buffer + 4; /* skip SMPTE 331M header */
    for (; buf_ptr < end_ptr; ) {
        for (i = 0; i < st->codec->channels; i++) {
            uint32_t sample = bytestream_get_le32(&buf_ptr);
            if (st->codec->bits_per_sample == 24)
                bytestream_put_le24(&data_ptr, (sample >> 4) & 0xffffff);
            else
                bytestream_put_le16(&data_ptr, (sample >> 12) & 0xffff);
        }
        buf_ptr += 32 - st->codec->channels*4; // always 8 channels stored SMPTE 331M
    }
    pkt->size = data_ptr - pkt->data;
    return 0;
}

static int mxf_decrypt_triplet(AVFormatContext *s, AVPacket *pkt, KLVPacket *klv)
{
    static const uint8_t checkv[16] = {0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b, 0x43, 0x48, 0x55, 0x4b};
    MXFContext *mxf = s->priv_data;
    ByteIOContext *pb = &s->pb;
    offset_t end = url_ftell(pb) + klv->length;
    uint64_t size;
    uint64_t orig_size;
    uint64_t plaintext_size;
    uint8_t ivec[16];
    uint8_t tmpbuf[16];
    int index;

    if (!mxf->aesc && s->key && s->keylen == 16) {
        mxf->aesc = av_malloc(av_aes_size);
        av_aes_init(mxf->aesc, s->key, 128, 1);
    }
    // crypto context
    url_fskip(pb, klv_decode_ber_length(pb));
    // plaintext offset
    klv_decode_ber_length(pb);
    plaintext_size = get_be64(pb);
    // source klv key
    klv_decode_ber_length(pb);
    get_buffer(pb, klv->key, 16);
    if (!IS_KLV_KEY(klv, mxf_essence_element_key))
        return -1;
    index = mxf_get_stream_index(s, klv);
    if (index < 0)
        return -1;
    // source size
    klv_decode_ber_length(pb);
    orig_size = get_be64(pb);
    if (orig_size < plaintext_size)
        return -1;
    // enc. code
    size = klv_decode_ber_length(pb);
    if (size < 32 || size - 32 < orig_size)
        return -1;
    get_buffer(pb, ivec, 16);
    get_buffer(pb, tmpbuf, 16);
    if (mxf->aesc)
        av_aes_crypt(mxf->aesc, tmpbuf, tmpbuf, 1, ivec, 1);
    if (memcmp(tmpbuf, checkv, 16))
        av_log(s, AV_LOG_ERROR, "probably incorrect decryption key\n");
    size -= 32;
    av_get_packet(pb, pkt, size);
    size -= plaintext_size;
    if (mxf->aesc)
        av_aes_crypt(mxf->aesc, &pkt->data[plaintext_size],
                     &pkt->data[plaintext_size], size >> 4, ivec, 1);
    pkt->size = orig_size;
    pkt->stream_index = index;
    url_fskip(pb, end - url_ftell(pb));
    return 0;
}

static int mxf_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    KLVPacket klv;

    while (!url_feof(&s->pb)) {
        if (klv_read_packet(&klv, &s->pb) < 0)
            return -1;
#ifdef DEBUG
        PRINT_KEY(s, "read packet", klv.key);
#endif
        if (IS_KLV_KEY(klv.key, mxf_encrypted_triplet_key)) {
            int res = mxf_decrypt_triplet(s, pkt, &klv);
            if (res < 0) {
                av_log(s, AV_LOG_ERROR, "invalid encoded triplet\n");
                return -1;
            }
            return 0;
        }
        if (IS_KLV_KEY(klv.key, mxf_essence_element_key)) {
            int index = mxf_get_stream_index(s, &klv);
            if (index < 0) {
                av_log(s, AV_LOG_ERROR, "error getting stream index\n");