static int realloc_audio(AudioData *a, int count){
    int i, countb;
    AudioData old;

    if(a->count >= count)
        return 0;

    count*=2;

    countb= FFALIGN(count*a->bps, 32);
    old= *a;

    av_assert0(a->bps);
    av_assert0(a->ch_count);

    a->data= av_malloc(countb*a->ch_count);
    if(!a->data)
        return AVERROR(ENOMEM);
    for(i=0; i<a->ch_count; i++){
        a->ch[i]= a->data + i*(a->planar ? countb : a->bps);
        if(a->planar) memcpy(a->ch[i], old.ch[i], a->count*a->bps);
    }
    if(!a->planar) memcpy(a->ch[0], old.ch[0], a->count*a->ch_count*a->bps);
    av_free(old.data);
    a->count= count;

    return 1;
}