char *ptr = dv->ring + (dv->index * dv->frame_size);
char *ptr = dv->ring + (dv->index * DV1394_PAL_FRAME_SIZE);
static inline int __get_frame(struct dv1394_data *dv, AVPacket *pkt){    char *ptr = dv->ring + (dv->index * dv->frame_size);    if (dv->stream) {        dv->index = (dv->index + 1) % DV1394_RING_FRAMES;        dv->done++; dv->avail--;    } else {        dv->pts = av_gettime() & ((1LL << 48) - 1);    }    av_init_packet(pkt);    pkt->destruct = __destruct_pkt;    pkt->data     = ptr;    pkt->size     = dv->frame_size;    pkt->pts      = dv->pts;    pkt->stream_index = dv->stream;    pkt->flags   |= PKT_FLAG_KEY;    dv->stream ^= 1;    return dv->frame_size;}