static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt) { AVFrame *frame = data; const uint8_t *buf = avpkt->data; const uint8_t *buf_end = buf + avpkt->size; KgvContext * const c = avctx->priv_data; int offsets[8]; uint8_t *out, *prev; int outcnt = 0, maxcnt; int w, h, i, res; if (avpkt->size < 2) w = (buf[0] + 1) * 8; h = (buf[1] + 1) * 8; buf += 2; if (w != avctx->width || h != avctx->height) { av_freep(&c->frame_buffer); av_freep(&c->last_frame_buffer); if ((res = ff_set_dimensions(avctx, w, h)) < 0) return res; } if (!c->frame_buffer) { c->frame_buffer = av_mallocz(avctx->width * avctx->height * 2); c->last_frame_buffer = av_mallocz(avctx->width * avctx->height * 2); if (!c->frame_buffer || !c->last_frame_buffer) { decode_flush(avctx); return AVERROR(ENOMEM); } } maxcnt = w * h; if ((res = ff_get_buffer(avctx, frame, 0)) < 0) return res; out = (uint8_t*)c->frame_buffer; prev = (uint8_t*)c->last_frame_buffer; for (i = 0; i < 8; i++) offsets[i] = -1; while (outcnt < maxcnt && buf_end - 2 >= buf) { int code = AV_RL16(buf); buf += 2; if (!(code & 0x8000)) { AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly outcnt++; } else { int count; if ((code & 0x6000) == 0x6000) { // copy from previous frame int oidx = (code >> 10) & 7; int start; count = (code & 0x3FF) + 3; if (offsets[oidx] < 0) { if (buf_end - 3 < buf) break; offsets[oidx] = AV_RL24(buf); buf += 3; } start = (outcnt + offsets[oidx]) % maxcnt; if (maxcnt - start < count || maxcnt - outcnt < count) break; if (!prev) { av_log(avctx, AV_LOG_ERROR, "Frame reference does not exist\n"); break; } memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count); } else { // copy from earlier in this frame int offset = (code & 0x1FFF) + 1; if (!(code & 0x6000)) { count = 2; } else if ((code & 0x6000) == 0x2000) { count = 3; } else { if (buf_end - 1 < buf) break; count = 4 + *buf++; } if (outcnt < offset || maxcnt - outcnt < count) break; av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count); } outcnt += count; } } if (outcnt - maxcnt) av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt); av_image_copy_plane(frame->data[0], frame->linesize[0], (const uint8_t*)c->frame_buffer, avctx->width * 2, avctx->width * 2, avctx->height); FFSWAP(uint16_t *, c->frame_buffer, c->last_frame_buffer); *got_frame = 1; return avpkt->size; }