movenc.c

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    put_be16(pb, 0x0100); /* reserved (preferred volume) 1.0 = normal */
    put_be16(pb, 0); /* reserved */
    put_be32(pb, 0); /* reserved */
    put_be32(pb, 0); /* reserved */

    /* Matrix structure */
    put_be32(pb, 0x00010000); /* reserved */
    put_be32(pb, 0x0); /* reserved */
    put_be32(pb, 0x0); /* reserved */
    put_be32(pb, 0x0); /* reserved */
    put_be32(pb, 0x00010000); /* reserved */
    put_be32(pb, 0x0); /* reserved */
    put_be32(pb, 0x0); /* reserved */
    put_be32(pb, 0x0); /* reserved */
    put_be32(pb, 0x40000000); /* reserved */

    put_be32(pb, 0); /* reserved (preview time) */
    put_be32(pb, 0); /* reserved (preview duration) */
    put_be32(pb, 0); /* reserved (poster time) */
    put_be32(pb, 0); /* reserved (selection time) */
    put_be32(pb, 0); /* reserved (selection duration) */
    put_be32(pb, 0); /* reserved (current time) */
    put_be32(pb, maxTrackID+1); /* Next track id */
    return 0x6c;
}

static int mov_write_udta_tag(ByteIOContext *pb, MOVContext* mov,
                              AVFormatContext *s)
{
    int pos = url_ftell(pb);
    int i;

    put_be32(pb, 0); /* size */
    put_tag(pb, "udta");

    /* Requirements */
    for (i=0; i<MAX_STREAMS; i++) {
        if(mov->tracks[i].entry <= 0) continue;
        if (mov->tracks[i].enc->codec_id == CODEC_ID_AAC ||
            mov->tracks[i].enc->codec_id == CODEC_ID_MPEG4) {
            int pos = url_ftell(pb);
            put_be32(pb, 0); /* size */
            put_tag(pb, "\251req");
            put_be16(pb, sizeof("QuickTime 6.0 or greater") - 1);
            put_be16(pb, 0);
            put_buffer(pb, "QuickTime 6.0 or greater",
                       sizeof("QuickTime 6.0 or greater") - 1);
            updateSize(pb, pos);
            break;
        }
    }

    /* Encoder */
    if(!(mov->tracks[0].enc->flags & CODEC_FLAG_BITEXACT))
    {
        int pos = url_ftell(pb);
        put_be32(pb, 0); /* size */
        put_tag(pb, "\251enc");
        put_be16(pb, sizeof(LIBAVFORMAT_IDENT) - 1); /* string length */
        put_be16(pb, 0);
        put_buffer(pb, LIBAVFORMAT_IDENT, sizeof(LIBAVFORMAT_IDENT) - 1);
        updateSize(pb, pos);
    }

    if( s->title[0] )
    {
        int pos = url_ftell(pb);
        put_be32(pb, 0); /* size */
        put_tag(pb, "\251nam");
        put_be16(pb, strlen(s->title)); /* string length */
        put_be16(pb, 0);
        put_buffer(pb, s->title, strlen(s->title));
        updateSize(pb, pos);
    }

    if( s->author[0] )
    {
        int pos = url_ftell(pb);
        put_be32(pb, 0); /* size */
        put_tag(pb, /*"\251aut"*/ "\251day" );
        put_be16(pb, strlen(s->author)); /* string length */
        put_be16(pb, 0);
        put_buffer(pb, s->author, strlen(s->author));
        updateSize(pb, pos);
    }

    if( s->comment[0] )
    {
        int pos = url_ftell(pb);
        put_be32(pb, 0); /* size */
        put_tag(pb, "\251des");
        put_be16(pb, strlen(s->comment)); /* string length */
        put_be16(pb, 0);
        put_buffer(pb, s->comment, strlen(s->comment));
        updateSize(pb, pos);
    }

    return updateSize(pb, pos);
}

static int mov_write_moov_tag(ByteIOContext *pb, MOVContext *mov,
                              AVFormatContext *s)
{
    int pos, i;
    pos = url_ftell(pb);
    put_be32(pb, 0); /* size placeholder*/
    put_tag(pb, "moov");
    mov->timescale = globalTimescale;

    for (i=0; i<MAX_STREAMS; i++) {
        if(mov->tracks[i].entry <= 0) continue;

        if(mov->tracks[i].enc->codec_type == CODEC_TYPE_VIDEO) {
            mov->tracks[i].timescale = mov->tracks[i].enc->frame_rate;
            mov->tracks[i].sampleDuration = mov->tracks[i].enc->frame_rate_base;
        }
        else if(mov->tracks[i].enc->codec_type == CODEC_TYPE_AUDIO) {
            /* If AMR, track timescale = 8000, AMR_WB = 16000 */
            if(mov->tracks[i].enc->codec_id == CODEC_ID_AMR_NB) {
                mov->tracks[i].sampleDuration = 160;  // Bytes per chunk
                mov->tracks[i].timescale = 8000;
            }
            else {
                mov->tracks[i].timescale = mov->tracks[i].enc->sample_rate;
                mov->tracks[i].sampleDuration = mov->tracks[i].enc->frame_size;
            }
        }

        mov->tracks[i].trackDuration = 
            mov->tracks[i].sampleCount * mov->tracks[i].sampleDuration;
        mov->tracks[i].time = mov->time;
        mov->tracks[i].trackID = i+1;
    }

    mov_write_mvhd_tag(pb, mov);
    //mov_write_iods_tag(pb, mov);
    for (i=0; i<MAX_STREAMS; i++) {
        if(mov->tracks[i].entry > 0) {
            mov_write_trak_tag(pb, &(mov->tracks[i]));
        }
    }

    mov_write_udta_tag(pb, mov, s);

    return updateSize(pb, pos);
}

int mov_write_mdat_tag(ByteIOContext *pb, MOVContext* mov)
{
    mov->mdat_pos = url_ftell(pb); 
    put_be32(pb, 0); /* size placeholder*/
    put_tag(pb, "mdat");
    return 0;
}

/* TODO: This needs to be more general */
int mov_write_ftyp_tag(ByteIOContext *pb, AVFormatContext *s)
{
    MOVContext *mov = s->priv_data;

    put_be32(pb, 0x14 ); /* size */
    put_tag(pb, "ftyp");

    if ( mov->mode == MODE_3GP )
        put_tag(pb, "3gp4");
    else
        put_tag(pb, "isom");

    put_be32(pb, 0x200 );

    if ( mov->mode == MODE_3GP )
        put_tag(pb, "3gp4");
    else
        put_tag(pb, "mp41");

    return 0x14;
}

static int mov_write_header(AVFormatContext *s)
{
    ByteIOContext *pb = &s->pb;
    MOVContext *mov = s->priv_data;
    int i;

    /* Default mode == MP4 */
    mov->mode = MODE_MP4;

    if (s->oformat != NULL) {
        if (!strcmp("3gp", s->oformat->name)) mov->mode = MODE_3GP;
        else if (!strcmp("mov", s->oformat->name)) mov->mode = MODE_MOV;

        if ( mov->mode == MODE_3GP || mov->mode == MODE_MP4 )
            mov_write_ftyp_tag(pb,s);
    }

    for (i=0; i<MAX_STREAMS; i++) {
        mov->tracks[i].mode = mov->mode;
    }

    put_flush_packet(pb);

    return 0;
}

static int mov_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    MOVContext *mov = s->priv_data;
    ByteIOContext *pb = &s->pb;
    AVCodecContext *enc = &s->streams[pkt->stream_index]->codec;
    MOVTrack* trk = &mov->tracks[pkt->stream_index];
    int cl, id;
    unsigned int samplesInChunk = 0;
    int size= pkt->size;

    if (url_is_streamed(&s->pb)) return 0; /* Can't handle that */
    if (!size) return 0; /* Discard 0 sized packets */

    if (enc->codec_type == CODEC_TYPE_VIDEO ) {
        samplesInChunk = 1;
    }
    else if (enc->codec_type == CODEC_TYPE_AUDIO ) {
        if( enc->codec_id == CODEC_ID_AMR_NB) {
            /* We must find out how many AMR blocks there are in one packet */
            static uint16_t packed_size[16] =
                {13, 14, 16, 18, 20, 21, 27, 32, 6, 0, 0, 0, 0, 0, 0, 0};
            int len = 0;

            while (len < size && samplesInChunk < 100) {
                len += packed_size[(pkt->data[len] >> 3) & 0x0F];
                samplesInChunk++;
            }
        }
        else if(enc->codec_id == CODEC_ID_PCM_ALAW) {
            samplesInChunk = size/enc->channels;
        }
	else if(enc->codec_id == CODEC_ID_PCM_S16BE || enc->codec_id == CODEC_ID_PCM_S16LE) {
	    samplesInChunk = size/(2*enc->channels);
        }	    
        else {
            samplesInChunk = 1;
        }
    }

    if ((enc->codec_id == CODEC_ID_MPEG4 || enc->codec_id == CODEC_ID_AAC)
        && trk->vosLen == 0) {
//        assert(enc->extradata_size);

        trk->vosLen = enc->extradata_size;
        trk->vosData = av_malloc(trk->vosLen);
        memcpy(trk->vosData, enc->extradata, trk->vosLen);
    }

    cl = trk->entry / MOV_INDEX_CLUSTER_SIZE;
    id = trk->entry % MOV_INDEX_CLUSTER_SIZE;

    if (trk->ents_allocated <= trk->entry) {
        trk->cluster = av_realloc(trk->cluster, (cl+1)*sizeof(void*)); 
        if (!trk->cluster)
            return -1;
        trk->cluster[cl] = av_malloc(MOV_INDEX_CLUSTER_SIZE*sizeof(MOVIentry));
        if (!trk->cluster[cl])
            return -1;
        trk->ents_allocated += MOV_INDEX_CLUSTER_SIZE;
    }
    if (mov->mdat_written == 0) {
        mov_write_mdat_tag(pb, mov);
        mov->mdat_written = 1;
        mov->time = s->timestamp;
    }

    trk->cluster[cl][id].pos = url_ftell(pb);
    trk->cluster[cl][id].samplesInChunk = samplesInChunk;
    trk->cluster[cl][id].size = size;
    trk->cluster[cl][id].entries = samplesInChunk;
    if(enc->codec_type == CODEC_TYPE_VIDEO) {
        trk->cluster[cl][id].key_frame = !!(pkt->flags & PKT_FLAG_KEY);
        if(trk->cluster[cl][id].key_frame)
            trk->hasKeyframes = 1;
    }
    trk->enc = enc;
    trk->entry++;
    trk->sampleCount += samplesInChunk;
    trk->mdat_size += size;

    put_buffer(pb, pkt->data, size);

    put_flush_packet(pb);
    return 0;
}

static int mov_write_trailer(AVFormatContext *s)
{
    MOVContext *mov = s->priv_data;
    ByteIOContext *pb = &s->pb;
    int res = 0;
    int i, j;

    offset_t moov_pos = url_ftell(pb);

    /* Write size of mdat tag */
    for (i=0, j=0; i<MAX_STREAMS; i++) {
        if(mov->tracks[i].ents_allocated > 0) {
            j += mov->tracks[i].mdat_size;
        }
    }
    url_fseek(pb, mov->mdat_pos, SEEK_SET);
    put_be32(pb, j+8);
    url_fseek(pb, moov_pos, SEEK_SET);

    mov_write_moov_tag(pb, mov, s);

    for (i=0; i<MAX_STREAMS; i++) {
        for (j=0; j<mov->tracks[i].ents_allocated/MOV_INDEX_CLUSTER_SIZE; j++) {
            av_free(mov->tracks[i].cluster[j]);
        }
        av_free(mov->tracks[i].cluster);
        if( mov->tracks[i].vosLen ) av_free( mov->tracks[i].vosData );

        mov->tracks[i].cluster = NULL;
        mov->tracks[i].ents_allocated = mov->tracks[i].entry = 0;
    }

    put_flush_packet(pb);

    return res;
}

static AVOutputFormat mov_oformat = {
    "mov",
    "mov format",
    NULL,
    "mov",
    sizeof(MOVContext),
    CODEC_ID_AAC,
    CODEC_ID_MPEG4,
    mov_write_header,
    mov_write_packet,
    mov_write_trailer,
};

static AVOutputFormat _3gp_oformat = {
    "3gp",
    "3gp format",
    NULL,
    "3gp",
    sizeof(MOVContext),
    CODEC_ID_AMR_NB,
    CODEC_ID_H263,
    mov_write_header,
    mov_write_packet,
    mov_write_trailer,
};

static AVOutputFormat mp4_oformat = {
    "mp4",
    "mp4 format",
    "application/mp4",
    "mp4,m4a",
    sizeof(MOVContext),
    CODEC_ID_AAC,
    CODEC_ID_MPEG4,
    mov_write_header,
    mov_write_packet,
    mov_write_trailer,
};

int movenc_init(void)
{
    av_register_output_format(&mov_oformat);
    av_register_output_format(&_3gp_oformat);
    av_register_output_format(&mp4_oformat);
    return 0;
}