static int zerocodec_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt) { ZeroCodecContext *zc = avctx->priv_data; AVFrame *pic = avctx->coded_frame; AVFrame *prev_pic = &zc->previous_frame; z_stream *zstream = &zc->zstream; uint8_t *prev, *dst; int i, j, zret; pic->reference = 3; if (avctx->get_buffer(avctx, pic) < 0) { av_log(avctx, AV_LOG_ERROR, "Could not allocate buffer.\n"); return AVERROR(ENOMEM); } zret = inflateReset(zstream); if (zret != Z_OK) { av_log(avctx, AV_LOG_ERROR, "Could not reset inflate: %d\n", zret); return AVERROR(EINVAL); } zstream->next_in = avpkt->data; zstream->avail_in = avpkt->size; prev = prev_pic->data[0]; dst = pic->data[0]; /** * ZeroCodec has very simple interframe compression. If a value * is the same as the previous frame, set it to 0. */ if (avpkt->flags & AV_PKT_FLAG_KEY) { pic->key_frame = 1; pic->pict_type = AV_PICTURE_TYPE_I; for (i = 0; i < avctx->height; i++) { zstream->next_out = dst; zstream->avail_out = avctx->width << 1; zret = inflate(zstream, Z_SYNC_FLUSH); if (zret != Z_OK && zret != Z_STREAM_END) { av_log(avctx, AV_LOG_ERROR, "Inflate failed with return code: %d\n", zret); return AVERROR(EINVAL); } dst += pic->linesize[0]; } } else { pic->key_frame = 0; pic->pict_type = AV_PICTURE_TYPE_P; for (i = 0; i < avctx->height; i++) { zstream->next_out = dst; zstream->avail_out = avctx->width << 1; zret = inflate(zstream, Z_SYNC_FLUSH); if (zret != Z_OK && zret != Z_STREAM_END) { av_log(avctx, AV_LOG_ERROR, "Inflate failed with return code: %d\n", zret); return AVERROR(EINVAL); } for (j = 0; j < avctx->width << 1; j++) dst[j] += prev[j] & -!dst[j]; prev += prev_pic->linesize[0]; dst += pic->linesize[0]; } } /* Release the previous buffer if need be */ if (prev_pic->data[0]) avctx->release_buffer(avctx, prev_pic); /* Store the previouse frame for use later */ *prev_pic = *pic; *data_size = sizeof(AVFrame); *(AVFrame *)data = *pic; return avpkt->size; }