USBTV_CHUNK
chunk_length = USBTV_CHUNK / frame_bytes;
u32 *dst = &frame[part_index * USBTV_CHUNK/2];
memcpy(dst, src, USBTV_CHUNK/2 * sizeof(*src));
src += USBTV_CHUNK/2;
unsigned size = USBTV_CHUNK * usbtv->n_chunks * 2 * sizeof(u32);
/ 4 / USBTV_CHUNK;